In vitro effect of human recombinant leptin and expression of leptin receptors on growth hormone-secreting human pituitary adenomas

OBJECTIVES: Untreated growth hormone deficiency (GHD) is implicated in the increased cardiovascular risk associated with adult hypopituitarism. Oxidative stress, predisposing to lipid peroxidation, may be an important mediator of endothelial dysfunction, a pro-atherogenic state associated with adult GHD. DESIGN AND PATIENTS: In a randomized, double-blind, placebo-controlled study we investigated the effects of GH replacement on low-density lipoprotein (LDL) oxidation and neutrophil superoxide (O(-)(2)) generating capacity in 32 GHD adults (19 males, 13 females; age range 19-64 years) over 3 months. Thirty age- and sex-matched healthy controls were also studied. MEASUREMENTS: Lipid hydroperoxides (HPOs) in plasma were measured using the ferrous oxidation with xylenol orange (FOX) assay. The susceptibility of LDL to oxidation was assessed by the copper-catalysed lag phase of LDL oxidation. Neutrophil O(-)(2)- generating capacity was assessed by a lucigenin-based chemiluminescent assay of NADPH oxidase activity. Body composition was assessed using bioelectrical impedance analysis. RESULTS: Compared to controls, GHD subjects had higher LDL cholesterol (4.0 +/- 0.8 vs. 3.5 +/- 0.9 mmol/l, P < 0.01) and higher triglyceride concentrations (2.3 +/- 1.5 vs. 1.1 +/- 0.7 mmol/l, P < 0.001) but lower HDL cholesterol (1.1 +/- 0.3 mmol/l vs. 1.4 +/- 0.4 mmol/l, P < 0.01), lower levels of HPOs (0.72 +/- 0.35 vs. 0.92 +/- 0.20 microm, P < 0.01) and lower basal (2.5 +/- 1.5 vs. 4.5 +/- 2.3 mV/5 x 10(5) neutrophils, P < 0.01) and peak post-activation levels (23.2 +/- 11.1 vs. 34.4 +/- 15.6 mV/5 x 10(5) neutrophils, P < 0.01) of neutrophil O(-)(2)- generation. GH replacement resulted in an increase in HPOs from 0.70 +/- 0.39 to 0.86 +/- 0.19 microm (P < 0.05), although there was no change in the lag time of LDL oxidation. Neutrophil O(-)(2)- generating capacity was enhanced with a rise in basal O(-)(2)- generation from 2.8 +/- 1.4 to 5.4 +/- 4.6 mV/5 x 10(5) neutrophils (P < 0.05) and in peak post-activation O(-)(2)- generation from 21.9 +/- 9.5 to 35.8 +/- 21.7 mV/5 x 10(5) neutrophils (P < 0.05). LDL cholesterol was reduced from 4.1 +/- 0.8 mmol/l to 3.5 +/- 0.8 mmol/l (P < 0.01). No significant changes in measured parameters occurred in the placebo group. CONCLUSIONS: Adult GHD is associated with reduced lipid peroxidation and impaired neutrophil O(-)(2)- generating capacity, both of which are reversible with GH replacement. Our data suggest that: (i) that oxidative stress is not a major feature of the pro-atherogenic state in hypopituitary adults with GHD and (ii) a role for GH in modulating neutrophil function and leucocyte-lipoprotein interactions.     

Different effects of short- and long-term recombinant hGH administration on ghrelin and adiponectin levels in GH-deficient adults

OBJECTIVE: To evaluate circulating levels of ghrelin and adiponectin (ApN) in GH-deficient (GHD) adults before and after short- and long-term recombinant human GH (rhGH) administration. PATIENTS AND METHODS: Twenty-three patients were studied. Seventeen subjects (Group A, 12 men, five women) were evaluated at baseline and after 1 year rhGH therapy (dose mean +/- SD: 0.3 +/- 0.1 mg/day) with the assessment of serum IGF-I, ghrelin, ApN, leptin, insulin and glucose levels, percentage of body fat (BF%), HOMA-IR and QUICKI. Seventeen age-, sex- and body mass index (BMI)-matched healthy subjects were recruited for comparisons. Six patients (Group B, three men, three women) underwent IGF-I generation test (rhGH 0.025 mg/kg/day for 7 days), blood sampled at baseline and on day 8 for determination of IGF-I, ghrelin and ApN levels. RESULTS: Group A: at baseline GHD patients showed low IGF-I levels and BF% significantly higher than controls (31.4 +/- 2.5 vs. 26.4 +/- 1.3, P < 0.05). Glucose, insulin, leptin, tryglicerides, low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol levels, as well as HOMA-IR and QUICKI values were similar in the two series, while total cholesterol levels were higher in GHD. In GHD, ghrelin levels were significantly lower than in controls (193.9 +/- 27.1 vs. 298.1 +/- 32.5 pmol/l, respectively, P = 0.02), while ApN levels were similar (10.2 +/- 1.1 and 9 +/- 1 mg/l, respectively, P = ns). After 1 year of rhGH therapy, BF%, BMI, serum total and LDL cholesterol significantly decreased, serum leptin levels showed a trend to decrease, while HOMA-IR and QUICKI did not change. Ghrelin and ApN levels significantly increased from 193.9 +/- 27.1 to 232.4 +/- 26.3 pmol/l (P < 0.01) and from 8.6 +/- 0.8 to 10.3 +/- 1.1 mg/l (P < 0.05), respectively. In group B, the expected increase in IGF-I levels was associated with a significant decrease in ghrelin levels, while ApN did not change. CONCLUSION: GHD patients showed serum ghrelin lower than controls, probably due to the higher BF%. No difference in ApN was observed. Ghrelin and ApN increments induced by long-term treatment may be related to the significant BMI and BF% reduction that is the predominant metabolic effect of rhGH therapy. Conversely, the decrease in ghrelin levels observed after short-term rhGH administration may be consistent with an inhibitory feedback of GH and/or IGF-I on ghrelin release.     

Serum homocysteine concentrations in children with growth hormone (GH) deficiency before and after 12 months GH replacement

OBJECTIVE: This open, prospective study was designed to evaluate the effect of growth hormone deficiency (GHD) and GH replacement therapy on serum homocysteine (Hcy) concentration in children with GHD. SUBJECTS: Seventeen prepubertal children with GHD (11 boys and six girls) aged 8.6 +/- 1.9 years were studied before and after 12 months of GH replacement therapy at a dose of GH of 30 microg/kg/day. Seventeen healthy children acted as controls and were matched for age, sex and body mass index (BMI). METHODS: At study entry, height, weight, blood pressure, serum Hcy, serum IGF-I, total-low density lipoprotein (LDL)- and high density lipoprotein (HDL) cholesterol, triglycerides, free T4, free T3, vitamin B12, folate, glucose and creatinine were measured in all subjects. The atherogenic index (AI) was also calculated as the ratio of total cholesterol/HDL cholesterol (T/HDL). In GHD children these parameters were also revaluated after 12 months of GH therapy. RESULTS: At study entry height and serum IGF-I were significantly lower, as expected, in GHD patients than in controls (P < 0.0001 and P < 0.007, respectively). Serum Hcy levels were significantly higher in GHD patients than in healthy children (8.4 +/- 2.9 vs. 6.0 +/- 2.9 micromol/l; P < 0.03), although the absolute values were within the normal values for age and sex. There were no significant differences at baseline with respect to blood pressure, serum vitamin B12, folate, fT3, fT4, lipid profile, creatinine and glucose levels. After 12 months of GH replacement therapy height and serum IGF-I increased significantly compared to pretreatment values (P < 0.0001); serum Hcy levels decreased significantly (6.0 +/- 3.3 micromol/l; P < 0.002) compared to baseline values, becoming similar to control values. Total cholesterol (3.5 +/- 0.6 mmol/l) and the AI (2.5 +/- 0.8) decreased significantly with respect to both pretreatment (4.2 +/- 1.0 mmol/l; P < 0.0002 and 3.4 +/- 0.8; < 0.002, respectively) and control values (4.2 +/- 0.4 mmol/l; P < 0.0005 and 3.3 +/- 1.1; P = 0.02, respectively). CONCLUSIONS: GHD in children is associated with higher serum levels of Hcy compared to controls, without significantly affecting the lipid profile. GH replacement for 12 months significantly decreased the Hcy levels and improved the lipid profile with a decrease of total cholesterol and the total/HDL cholesterol ratio, compared to pretreatment values. Given the small number of patients, further larger studies are needed to clarify whether these results may have significant effects in the prevention of cardiovascular disease in adulthood.     

Recombinant GH replacement in hypopituitary adults improves endothelial cell function and reduces calculated absolute and relative coronary risk

OBJECTIVE: Adult GH deficiency (GHD) is linked to endothelial dysfunction and vascular disease. We examined the effect of 12 months of GH therapy on endothelial function, C-reactive protein (CRP) and coronary risk. DESIGN: Open-design intervention study. PATIENTS: Fourteen GH-deficient patients (nonsmokers, without diabetes, hypertension or vascular disease) studied before, 6 months and 12 months after GH therapy. MEASUREMENTS: Flow-mediated dilatation (FMD), carotid intima-media thickness (IMT) thrombomodulin (TM), E-selectin, CRP, lipid profile, blood pressure and anthropometric data were recorded. We used the Framingham equation to calculate coronary risk. RESULTS: FMD improved (7.5 +/- 1.62 vs. 11.93 +/- 1.52, P = 0.038). Overall there was no change in IMT, TM, E-selectin or CRP. The correlation between TM and FMD showed a trend for statistical significance (r = -0.54, P = 0.056). Changes in CRP correlated with change in IGF-1 (r = -0.67, P = 0.012); E-selectin correlated with high density lipoprotein (HDL)-cholesterol (r = -0.60, P = 0.028), triglycerides (r = 0.68, P = 0.01) and waist-to-hip ratio (WHR) (r = 0.71, P = 0.006). Systolic (127.36 +/- 4.47 vs. 120.36 +/- 3.50, P = 0.017) and diastolic (84.71 +/- 2.73 vs. 76.93 +/- 2.03, P = 0.005) blood pressure decreased. HDL-cholesterol increased (0.70 +/- 0.05 vs. 0.93 +/- 0.06, P = 0.001). WHR decreased (0.90 +/- 0.02 to 0.88 +/- 0.02, P = 0.043) without changes in weight or body mass index (BMI). Ten-year absolute (P = 0.009) and relative (P = 0.002) cardiac risk decreased. CONCLUSION: Biophysical test of endothelial function (FMD) improved after 12 months of GH therapy but there was no significant change in biochemical endothelial or inflammatory markers. Calculated coronary risk decreased mainly due to reduction in systolic and diastolic blood pressure and increase in HDL-cholesterol.     

Elderly people with hypothalamic-pituitary disease and untreated GH deficiency: clinical outcome, body composition, lipid profiles and quality of life after 2 years compared to controls

OBJECTIVE: Elderly patients with GH deficiency (GHD) have significant impairments in multiple aspects of quality of life (QOL) but similar lipid profiles compared to age-matched control subjects. There are, however, no data on changes in these parameters with time. This study assessed the impact of untreated GHD over a period of 2 years in a group of elderly patients with hypothalamic-pituitary disease in relation to new illnesses and differences in body composition, circulating lipid profile levels and QOL. Control subjects were also followed for 2 years. SUBJECTS: Twenty-seven elderly patients (> 65 years) with hypothalamic-pituitary disorders and GHD (mean peak stimulated GH response 1.6 mIU/l, range 0.6--5.0) were studied initially. Two years later 21 (13 males) agreed to attend for reassessment. Mean age was then 72.7 +/- 5.04 years (range 67--85). Eighteen patients had pituitary tumours, three had craniopharyngiomas. Twenty-seven control subjects were studied at baseline and 17 (7 males) agreed to attend for reassessment. Mean age was then 75.9 +/- 6.97 years (range 67--88). METHODS: Weight, body mass index (BMI), total fat mass (FM) (bioelectrical impedance), serum IGF-1 and fasting lipid profile (total cholesterol, triglyceride, HDL cholesterol, LDL cholesterol) were measured. QOL was assessed in both groups using five interviewer-administered self-rating questionnaires: the Nottingham Health Profile, Short Form-36, Hospital Anxiety and Depression Scale, Mental Fatigue Questionnaire and Life Fulfillment Scale. The GHD group also completed the Disease Impact Scale. RESULTS: Two of the 27 patients with GHD died during the 2-year follow-up (myocardial infarction and probable cerebrovascular accident). Four controls could not be traced but there were no deaths in the other 23. In the 21 GHD patients after 2 years, mean serum IGF-1 and BMI were unchanged (12.6 +/- 5.8 vs. 13.3 +/- 5.1 nmol/l, P = 0.5 and 28.3 +/- 4.3 vs. 29.1 +/- 4.2, P = 0.5, respectively) at the 2-year follow-up and there were no significant changes in the lipid profiles. However, there was a significant reduction in fat mass (31.7 +/- 11.2 vs. 28.5 +/- 10.9%, P = 0.04). In the 17 control subjects after 2 years, serum IGF-1 levels (17.2 +/- 4.0 vs. 15.7 +/- 5.6 nmol/l, P = 0.4), BMI and fat mass were unchanged. However, there was a significant fall in total cholesterol levels over the 2-year follow-up (6.3 +/- 0.9 vs. 5.7 +/- 0.9 mmol/l, P < 0.0001), although LDL cholesterol, triglycerides and HDL cholesterol were unchanged. Analysing the QOL data, the GHD patients had less energy (P < 0.05), more depression (P < 0.05), more pain (P < 0.05) and lower life fulfillment scores (P < 0.01) after 2 years. However, the control subjects also had less energy (P < 0.05), less vitality (P < 0.05) and lower self-esteem (P < 0.05), more depression (P < 0.05), worse mental health (P < 0.05), life fulfillment personal (P < 0.01), life fulfillment material (P < 0.02), physical functioning and role physical functioning (P < 0.05) after 2 years. Comparing the patients and controls at baseline, there were significant differences in IGF-1, BMI, FM, LDL cholesterol, personal life fulfillment, mental fatigue, general health and mental health. However, after 2 years, only BMI and depression scores were significantly different. CONCLUSION: These patients with untreated GHD did not have deterioration of body composition or lipid profiles when reassessed after a period of 2 years. In fact, fat mass fell. The control subjects did have a significant decrease in total cholesterol but no change in other lipids or body composition. Some quality of life domains did deteriorate in the patients with GHD. However, the control subjects also had worse quality of life scores after 2 years which were then little different from the GHD patients. These results raise doubts about the benefits of GH replacement in elderly people with GHD.     

Short- and long-term effects of growth hormone (GH) replacement on protein metabolism in GH-deficient adults

Reduced fat-free mass (FFM) in GH-deficient (GHD) adults is improved by GH replacement, but the protein metabolic changes are unclear. Using iv [(2)H(3)]leucine and oral l-[(13)C(1)]leucine infusions and dual emission x-ray absorptiometry, we compared leucine kinetics and body composition in eight GHD adults and eight healthy controls in the fasted and fed states, before and after 2 wk and 6 months of GH replacement. Leucine kinetics were not different between pretreatment GHD subjects and controls. After 2 wk of GH treatment, leucine oxidation decreased in the GHD subjects compared with baseline values [fasted, 41 +/- 6 vs. 30 +/- 5 micromol/kg FFM.h (P < 0.01); fed, 49 +/- 3 vs. 41 +/- 3.6 micromol/kg FFM.h (P < 0.05)], leucine balance improved [fasted, -14 +/- 4 vs. -3.5 +/- 3 micromol/kg FFM.h (P < 0.01); fed, 65 +/- 10 vs. 72 +/- 7 micromol/kg FFM.h (P = 0.07)], and protein synthesis increased [fasted, 116 +/- 5 vs. 131 +/- 6 micromol/kg FFM.h (P < 0.05); fed, 103 +/- 6 vs. 116 +/- 6 micromol/kg FFM.h (P < 0.05)]. After 6 months of GH treatment, these changes were not maintained in the fed state. The five GHD subjects with decreased FFM at baseline showed a significant increase after 6 months of GH treatment (P < 0.05). GH replacement in GHD acutely improves protein balance by stimulating synthesis and inhibiting catabolism. After 6 months, protein kinetics reached a new homeostasis to maintain the net gain in FFM.     

Cardiac mass and function, carotid artery intima-media thickness, and lipoprotein levels in growth hormone-deficient adolescents

The objective of our study was to evaluate whether cardiac mass and function, carotid artery intima-media thickness, and serum lipid and lipoprotein(a) levels are abnormal in adolescents with GH deficiency. Young adults with childhood-onset and adulthood-onset GH deficiency have been found to have a higher cardiovascular risk, as manifested among other factors by reduced left ventricular mass, impaired systolic function, significant increase in arterial intima-media thickness, and dyslipidemia. Twelve adolescents (seven males and five females) with GH deficiency (10 idiopathic and 2 organic), with an age of 14.2 +/- 2.8 yr and a height of 140.6 +/- 17.9 cm (height SD score, -2.6 +/- 0.3), were studied. Six children had received GH in the past but were off therapy for several years, whereas six patients had never been treated with GH. Fasting blood samples were obtained for serum lipids and lipoprotein(a) analysis. Patients underwent transthoracic M-mode and two-dimensional echocardiographic evaluation for measurement of interventricular septal thickness, left ventricular posterior wall thickness, and left ventricular mass, as well as left ventricular ejection fraction at rest and pulmonary venous flow velocities; carotid artery intima-media thickness was measured using high-resolution mode B ultrasound. Seven GH-deficient (GHD) adolescents on GH at the time of the study and 19 healthy adolescents, all comparable for age, pubertal status, height, weight, blood pressure, and pulse, participated in this study as controls. Interventricular septal thickness (6.5 +/- 1.3 vs. 7.0 +/- 1.5 mm), left ventricular posterior wall thickness (7.0 +/- 1.8 vs. 7.5 +/- 2.0 mm), and left ventricular mass after correction for body surface area (71.2 +/- 21.8 vs. 70.7 +/- 18.0 g/m(2)) were similar in untreated GHD patients and healthy controls. Similarly, the left ventricular ejection fraction at rest was similar in untreated GHD subjects and controls (70.0 +/- 0.7 vs. 70.0 +/- 0.6%), as were the pulmonary venous flow velocities (0.54 +/- 0.16 vs. 0.55 +/- 0.10 m/s for diastolic peak velocity; 0.51 +/- 0.16 vs. 0.50 +/- 0.09 m/s for systolic peak velocity; and 0.19 +/- 0.06 vs. 0.19 +/- 0.05 m/s for atrial reversal filling). Carotid artery intima-media thickness (0.60 +/- 0.02 mm and 0.59 +/- 0.02 mm for the right and left carotid arteries, respectively) was also normal in our untreated GHD patients when compared with healthy controls. In addition, all echocardiographic measurements were similar in GHD subjects on or off GH at the time of the study. Low-density lipoprotein cholesterol levels were increased in untreated GHD patients when compared with healthy controls (3.17 +/- 0.70 vs. 2.33 +/- 0.36 mmol/L; P < 0.01), whereas total cholesterol, high-density lipoprotein cholesterol, and triglyceride concentrations were similar to that of controls. Total cholesterol levels were increased in our untreated GHD adolescents when compared with GHD subjects receiving GH therapy at the time of the study, while low-density lipoprotein cholesterol and triglyceride levels were also elevated, although not significantly. Lipoprotein(a) levels were elevated in untreated GHD adolescents when compared with healthy controls, and untreated GHD subjects had higher lipoprotein(a) concentrations than GH-treated patients. GHD adolescents, regardless of whether or not they received GH therapy, do not seem to show alterations in cardiac mass and function or early atherosclerotic changes. They must, however, be followed carefully because they already present cardiovascular risk factors such as dyslipidemia, which may increase their cardiovascular morbidity over time.     

Alterations in the oxidant-antioxidant status in prepubertal children with growth hormone deficiency: effect of growth hormone replacement therapy

OBJECTIVE: Growth hormone deficiency (GHD) in adults is associated with increased oxidative stress determined by the underlying GH-IGF-1 axis alterations. Despite GHD being a common diagnosis in children with short stature, no data on the oxidant/antioxidant status are available in this age group. This study was designed to detect differences in oxidative stress parameters between prepubertal GH-deficient children and healthy controls. Furthermore, the effect of 12 months of conventional GH replacement (rGH) on oxidant-antioxidant status was evaluated in the GHD group only. PATIENTS: Ten (nine males and one female) prepubertal children (mean age 9.1 +/- 1.3 years) with GHD were recruited and matched for sex and age (9.2 +/- 1.9 years) with 20 healthy controls (18 males and two females). MEASUREMENTS: At study entry, lag phase, an index of susceptibility of low density lipoprotein (LDL) to in vitro oxidation, malondialdehyde (MDA) and vitamin E were measured in all subjects. These parameters were also evaluated in GH-deficient children after 12 months of rGH treatment. RESULTS: The lag phase was significantly decreased in GH-deficient children compared to healthy controls (15.50 +/- 7.4 vs. 43.00 +/- 9.2 min; P = 0.0007), while MDA was significantly increased (1.33 +/- 0.38 vs. 0.46 +/- 0.10 nmol/mg; P = 0.0006). Vitamin E levels were significantly decreased (22.44 +/- 9.57 vs. 35.38 +/- 16.49 micromol/l; P = 0.001). IGF-1 and IGFBP-3 correlated directly to lag phase (r = 0.48; P = 0.01; r = 0.63, P = 0.002, respectively) and to vitamin E (r = 0.59, P = 0.003; r = 0.58, P = 0.006, respectively). By contrast, IGF-1 and IGFBP-3 correlated indirectly to MDA (r = -0.47, P = 0.01; r =-0.65, P = 0.002, respectively). After 1 year of rGH therapy, lag phase (39.32 +/- 15.24 min; P = 0.005) and vitamin E (34.9 +/- 7.7 micromol/l; P = 0.005) increased significantly, while MDA decreased significantly (0.71 +/- 0.42 nmol/mg; P = 0.005), reaching normal levels. CONCLUSIONS: These data show that children with GHD have substantially increased oxidative stress parameters compared to healthy controls and demonstrate a normalization of these parameters after 1 year of rGH therapy.     

The study of spontaneous GH secretion after 36-h fasting distinguishes between GH-deficient and normal adults

OBJECTIVE: Within an appropriate clinical context, GH deficiency (GHD) in adults can only be diagnosed biochemically by provocative testing. The evaluation of IGF-I, IGFBP-3 and even of spontaneous GH secretion do not establish the diagnosis of adult GHD. In fact, remarkable overlaps between normal and GHD adults have been reported for all these parameters. On the other hand, it is well known that even short-term fasting stimulates GH secretion in normal subjects. The aim of our study was to determine the effects of 36 h fasting on 8-h diurnal GH, insulin and glucose levels as well as on basal IGF-I, IGFBP-3, acid-labile subunit (ALS), IGFBP-1, GHBP and free fatty acid (FFA) levels. SUBJECTS: We studied 9 GHD adults (GHD, 8 males, 1 female; age, mean +/- SEM: 37.6 +/- 2.3 years, body mass index (BMI): 24.5 +/- 1.0 kg/m2) and 20 age-matched normal subjects (NS) as controls (13 males, 7 females; age: 28.9 +/- 0.6 years, BMI: 21.6 +/- 0.4 kg/m2). STUDY DESIGN: In all subjects we studied the effects of 36 h fasting on 8-h daytime GH, insulin and glucose levels (assay every 30 min from 0800 h to 1600 h) as well as on basal IGF-I, IGFBP-3, ALS, IGFBP-1, GHBP and FFA levels. RESULTS: Before fasting, basal mean IGF-I, IGFBP-3 and ALS levels in GHD were lower (P < 0. 0001) than in NS. IGFBP-1, GHBP and FFA levels were similar in both groups. Before fasting mean GH concentration (mGHc) in GHD was lower (P < 0.05) than in NS (0.4 +/- 0.2 vs. 2.2 +/- 0.6 mu/l) but with a clear overlap between the 2 groups (range 0.4-0.8 vs. 0.4-6.8 mu/l). After fasting, both in GHD and NS basal IGF-I, IGFBP-3, ALS and GHBP levels did not change significantly. On the other hand, in both GHD and in NS IGFBP-1 was increased (P < 0.0001) to a similar extent, while FFA increased in NS more (P < 0.01) than in GHD. Fasting significantly increased mGHc in NS (12.0 +/- 1.2 mu/l, P < 0.0001) but not in GHD (0.6 +/- 0.2 mu/l). After fasting, no overlap was present between GHD and NS (0.4-1.6 vs. 2.4-20.8 mu/l, respectively). Mean glucose and insulin concentrations over 8 h in GHD and NS in basal conditions were similar and were reduced to the same extent in both groups. CONCLUSIONS: Our findings demonstrate that after short-term fasting, the study of spontaneous GH secretion distinguishes between GH-deficient adults and normal subjects; this phenomenon occurs before significant changes in IGF-I and IGFBP-3 levels. These results suggest that the assessment of spontaneous GH secretion could be useful for the diagnosis of adult GH deficiency only after short-term fasting.     

Left ventricular mass and function in children with GH deficiency before and during 12 months GH replacement therapy

OBJECTIVE: This open, prospective study was designed to evaluate the effect of GH deficiency (GHD) on left ventricular (LV) mass (LVM) and performance, by echocardiography, and on lipid profile during childhood. SUBJECTS: Twelve prepubertal children with GHD (eight boys and four girls) aged 8.1 +/- 1.7 years were studied before and after 6 and 12 months of GH replacement therapy at a dose of GH of 30 micro g/kg/day. Twelve healthy children sex-, height-, weight- and body surface area-matched with the patients, served as controls. METHODS: Echocardiography was performed at study entry and after 12 months both in GHD children and in controls. Only in GHD children, echocardiography was repeated also after 6 months of GH replacement. In all subjects, we measured LV posterior wall thickness (LVPWT), LV end-diastolic diameter (LVEDD), LVM index (LVMi), LV systolic and diastolic function. RESULTS: At study entry, LVPWT (5.3 +/- 0.8 vs. 6.2 +/- 1.1 mm, P < 0.05), LVEDD (34.0 +/- 2.4 vs. 36.7 +/- 2.1 mm, P < 0.007) and LVMi (47.0 +/- 6.9 vs. 59.6 +/- 9.5 g/m2, P < 0.005) were significantly lower in GHD children than in controls. Lipid profile, heart rate, blood pressure, LV systolic function and indices of ventricular filling were similar in patients and controls. After 12 months of GH replacement therapy, LVPWT (6.1 +/- 0.7 mm, P < 0.0005), LVEDD (38.8 +/- 4.3 mm, P < 0.002) and LVMi (71.5 +/- 12.7 g/m2, P < 0.0005) significantly increased in GHD children compared to pretreatment values. In particular, after 12 months of therapy GHD children achieved a normal LVMi when compared to controls (60.7 +/- 8.6, P = ns). LVMi increase was significantly correlated with the increase in IGF-I level (r = 0.49; P < 0.004). LV systolic performance, diastolic filling and blood pressure did not change significantly during GH therapy. After 12 months of treatment, the atherogenic index, measured as total/high-density lipoprotein-cholesterol ratio (2.7 +/- 0.8) was significantly lower than both pretreatment (3.4 +/- 0.3, P < 0.03) and control values (3.8 +/- 1.1, P < 0.04). CONCLUSIONS: GH deficiency in children affects heart morphology, by inducing a significant decrease in cardiac size, but does not modify cardiac function and lipid profile. Twelve months of GH replacement treatment normalizes cardiac mass, and reduces the atherogenic index.     

Endothelial dysfunction in hypopituitary adults with growth hormone deficiency

OBJECTIVES: Adult hypopituitarism with growth hormone deficiency (GHD) results in reduced exercise capacity, detrimental changes in body composition and lipid profiles and may be associated with an excess cardiovascular mortality. Endothelial dysfunction is an early event in the pathogenesis of atherosclerosis and predisposes to the deposition of unstable atherosclerotic plaques. We have used a noninvasive method to assess endothelial function in the brachial arteries of a group of treated hypopituitary adults with GHD, and a group of healthy age- and sex-matched controls. PATIENTS: Seventeen hypopituitary adults with GHD (13 male, 4 female) aged 26-54 years were studied. Each patient was receiving standard replacement therapy for all other hormonal deficiencies such that all target hormones were maintained in the normal reference range. All observations obtained were compared with those made in age- and sex-matched control subjects. All study subjects had no identifiable risk factors for endothelial dysfunction. MEASUREMENTS: Using an ultrasound vessel wall tracking system, the diameter of the left brachial artery was measured at rest, in response to reactive hyperaemia (endothelium-dependent dilation) and following sublingual glyceryl trinitrate (GTN) (endothelium-independent vasodilatation). We also measured fasting lipids, insulin, plasma glucose, glycated haemoglobin (HbA1c) and IGF-1, and studied the relationship of these parameters to endothelial function. RESULTS: Flow mediated endothelium-dependent dilatation (FMD), expressed as a percentage change from resting base-line diameter, was significantly impaired in the GHD group (3.70 +/- 2.36% vs. 7.30 +/- 2.42%, P < 0.001). In contrast, GTN-mediated dilatation was similar in both groups. There were no differences in total cholesterol, HDL cholesterol, LDL cholesterol or plasma triglyceride between the groups. Both fasting insulin (27.1 +/- 18.1 vs. 15.89 +/- 6.65 mU/l, P < 0.05) and glycated haemoglobin (HbA1c) levels (5.29 +/- 0.43 vs. 4.91 +/- 0.43%, P < 0.05) were significantly higher in the GHD group. FMD in both groups showed an inverse relationship with total cholesterol (r = -0.58, P < 0.05, GHD and r = -0.55, P < 0.05 controls). However, in the GHD subjects, there was a strong inverse relationship between FMD and LDL-cholesterol (r = -0.81, P < 0.0001). No other relationships were noted between FMD and any other metabolic parameters, or characteristics of GHD. CONCLUSIONS: Endothelial dysfunction is present in GH deficient adults prior to the onset of overt atherosclerotic disease. The similar glucose yet elevated fasting insulin levels imply a state of relative insulin insensitivity. The strong inverse correlation between endothelial dysfunction and LDL-cholesterol suggests a possible aetiological role for LDL-cholesterol in the pathogenesis of any excess cardiovascular risk associated with adult hypopituitarism.     

Increased orderliness of growth hormone (GH) secretion in GH-deficient adults with low serum insulin-like growth factor I

Available studies suggest that a proportion of GH-deficient (GHD) adults maintain serum IGF-I concentrations within the age- and sex-matched normal range. The basis for this distinction is not known. In this study 24-h GH profiles (sampling every 30 min) were appraised in five GHD adults with low serum IGF-I concentrations (<2 SD of the age- and sex-matched normal range), five GHD adults with normal serum IGF-I levels (within +/-2 SD), and five healthy subjects. Serial GH concentrations, measured using a chemiluminescence assay, were analyzed by deconvolution and approximate entropy (ApEn; regularity) analyses. The apparent half-duration of GH secretory bursts was longer in both GHD groups than in the healthy controls, as determined by deconvolution analysis (P < 0.05 each). The GH burst frequency was higher, the interburst interval was shorter, and the GH burst amplitude was lower in GHD adults with normal serum IGF-I than in healthy controls (P < 0.05, P < 0.05, and P < 0.01, respectively). The percentage of total daily GH secretion that was pulsatile was also reduced in the GHD adults with normal serum IGF-I compared with the other two groups (P < 0.05 and P < 0.05, respectively). In contrast, ApEn ratios were lower in the GHD adults with low serum IGF-I than in the GHD adults with normal IGF-I and controls (P < 0.01 and P < 0.05, respectively). Serum IGF-I concentrations correlated positively with ApEn ratios in the total study population (n = 15) and in the GHD adults (n = 10). In conclusion, 24-h patterns of GH release differed in GHD adults with low vs. normal serum IGF-I concentrations. GHD adults with low IGF-I levels maintain low ApEn ratios (denoting greater relative orderliness of GH secretion), whereas GHD patients with normal IGF-I values generate a high frequency, low amplitude GH output. The foregoing contrasts point to distinct neuroendocrine features of the GH-deficient state of adults, which can be related to concurrent IGF-I production.     

The effects of depot long-acting somatostatin analog on central aortic pressure and arterial stiffness in acromegaly

Acromegaly is associated with increased cardiovascular risk. Although conventional risk factors such as glucose intolerance, hypertension, and dyslipidemia probably contribute, there may also be direct effects of GH/IGF-I excess on the vasculature. To study the effects of GH excess on the vasculature, we have assessed arterial stiffness in acromegalic subjects with and without active disease and have investigated the effects of Sandostatin LAR (OCT-LAR) on vascular function. Sixteen normotensive subjects with acromegaly (10 males and 6 females) and 8 healthy controls were studied. Of the acromegalic subjects, eight had active disease (group A), and eight were cured (GH < 2.5 mU/liter; group B). The three groups were age, sex, and blood pressure matched. Group A subjects were restudied after 3 and 6 months of OCT-LAR therapy. Arterial stiffness was assessed by analyzing central arterial pressure waveforms derived from measured radial artery waveforms. This allowed determination of the augmentation of central pressure and the augmentation index. Lipids, glucose, and IGF-I were also measured. Comparing the three groups (ANOVA; mean +/- SD), the augmentation index was higher in group A (28 +/- 12 vs. 12 +/- 13%; P < 0.01) but not in group B (22 +/- 7 vs. 12 +/- 13%; P = 0.60), compared with controls. IGF-I was higher in group A (50.3 +/- 21.2 nmol/liter; P < 0.01), compared with group B (22.5 +/- 8.9 nmol/liter) and controls (19.5 +/- 5.3 nmol/liter). On regression analysis, IGF-I concentration was identified as a strong independent predictor of the augmentation index (beta = 0.50; P = 0.007). There were no significant differences in aortic systolic pressure, aortic diastolic pressure, lipids, or glucose. Compared with baseline, OCT-LAR treatment resulted in a lowering of augmentation index at 3 months (20 +/- 15 vs. 28 +/- 12%; P < 0.05), but at 6 months (24 +/- 16%; P = 0.21) there was no significant change. IGF-I was reduced from 50.3 +/- 21.2 nmol/liter at baseline to 31.4 +/- 13.2 nmol/liter at 3 months (P < 0.05) and 26.6 +/- 15.8 nmol/liter at 6 months (P < 0.05). In conclusion, acromegaly is associated with changes in the central arterial pressure waveform, suggesting large artery stiffening. This may have important implications for cardiac morphology and performance in acromegaly as well as increasing the susceptibility to atheromatous disease. Large artery stiffness is reduced in cured acromegaly and partially reversed after pharmacological treatment of active disease.     

The natural history of partial growth hormone deficiency in adults: a prospective study on the cardiovascular risk and atherosclerosis

BACKGROUND: Partial GH deficiency (GHD) in adults is poorly studied. OBJECTIVE: The objective of the study was to investigate the natural history and clinical implications of partial GHD. STUDY DESIGN: This was an analytical, observational, prospective, case-control study. PATIENTS: Twenty-seven hypopituitary patients (15 women, ages 20-60 yr) and 27 controls participated in the study. MAIN OUTCOME MEASURES: Measures included GH peak after GHRH plus arginine [(GHRH+ARG), measured by immunoradiometric assay]; IGF-I (measured after ethanol extraction) z-sd score (SDS); glucose, insulin, total cholesterol, high-density lipoprotein (HDL) cholesterol, and triglyceride levels; and common carotid arteries intima-media thickness (IMT) measured periodically. RESULTS: At study entry, partial GHD patients had significantly lower IGF-I and HDL-cholesterol levels and homeostasis model assessment index than controls. During the 60 months of median follow-up, 11 patients had severe GHD (40.7%), seven normalized their GH response (25.9%), and nine showed persistently partial GHD (33.3%). Patients with developed severe GHD at baseline had similar age and body mass index and lower GH peak (11.5 +/- 1.8 vs. 14.3 +/- 1.5 and 12.8 +/- 1.1 microg/liter, P = 0.008) and IGF-I SDS (-0.88 +/- 0.48 vs. 0.15 +/- 0.58 and -0.42 +/- 0.78; P = 0.01) than the patients with normal GH secretion or partial GHD. Severe GHD was accompanied by decreased IGF-I SDS and increased total to HDL cholesterol ratio, triglycerides, homeostasis model assessment index, and carotid intima-media thickness; normalization of GH secretion was accompanied by increased IGF-I SDS. By receiving-operator characteristic analysis, predictors of severe GHD were a baseline GH peak after GHRH+ARG of 11.5 microg/liter (sensitivity 64%, specificity 94%) and a baseline IGF-I SDS of -0.28 (sensitivity 91%, specificity 63%). CONCLUSIONS: Of 27 patients with partial GHD after pituitary surgery, 40.7% developed severe GHD and 25.9% normalized their GH response. With the assay used, changes in the GH peak response to GHRH+ARG were accompanied by changes in the IGF-I SDS, metabolic profile, and carotid IMT. A peak GH of 11.5 microg/liter or less and IGF-I SDS -0.28 or less were highly predictive of delayed deterioration of GH secretion.     

Preservation of dopaminergic and alpha-adrenergic function in children with growth hormone neurosecretory dysfunction

The integrity of dopaminergic and alpha-adrenergic neurotransmitter regulation of GH secretion was examined in children with decreased GH secretion. Children with GH neurosecretory dysfunction (GHND; n = 16) those with classical GH deficiency (n = 9), and short but otherwise normal children (n = 12) underwent 24 h GH studies (blood sampling every 20 min for 24 h) and provocative tests using arginine, insulin hypoglycemia, L-dopa (dopaminergic) and clonidine (alpha-adrenergic), and GH-releasing hormone (GHRH). GHND was defined as children with height in the first percentile or below, growth velocity of 4 cm/yr or less, low plasma somatomedin-C for age, delayed skeletal age by 2 or more yr, peak serum GH responses to any one (or more) provocative test of 10 ng/ml or more, and mean 24-h GH concentration below 3 ng/ml. GHND and GH-deficient children had reduced endogenous GH secretion, expressed as mean serum 24-h GH concentration [1.6 +/- 0.1 (+/- SEM) and 2.1 +/- 0.1 vs. 6.1 +/- 0.5 ng/ml (GH-deficient and GHND vs. normal, respectively); P less than 0.01]. the mean peak serum GH levels after arginine [8.2 +/- 2.0 vs. 20.8 +/- 6.6 ng/ml (GHND vs. normal); P less than 0.05] and insulin [9.3 +/- 1.0 vs. 16.2 +/- 1.7 ng/ml (GHND vs. normal); P less than 0.01) were lower in GHND children. The mean peak responses after L-dopa [13.4 +/- 3.4 vs. 14.6 +/- 4.7 ng/ml (GHND vs. normal); P = NS] and clonidine [19.0 +/- 2.2 vs. 23.3 +/- 3.8 ng/ml (GHND vs. normal); P = NS] were preserved in GHND children. In GH-deficient children, mean peak serum GH concentrations after all four provocative tests were low (arginine, 2.7 +/- 0.8; insulin, 2.6 +/- 0.8; L-dopa, 3.0 +/- 0.9; clonidine, 3.4 +/- 1.0 ng/ml; all P less than 0.01 vs. normal). The mean peak serum GH concentration after GHRH was blunted in GH-deficient children (9.1 +/- 1.7 ng/ml) compared to those in GHND (32.9 +/- 8.5 ng/ml) and normal (43.2 +/- 6.4 ng/ml) children (P less than 0.01). The area under the GH curve after GHRH stimulation was greater for normal than GHND children (P less than 0.05). These data demonstrate preservation of dopaminergic and alpha-adrenergic neurotransmitter pathways in GHND children. They further suggest a defect in the release of pituitary GH secondary to an abnormality in alternative neurotransmitter pathways resulting in decreased GHRH and/or increased somatostatin secretion.     

Growth and adult height in GH-treated children with nonacquired GH deficiency and idiopathic short stature: the influence of pituitary magnetic resonance imaging findings

We analyzed the final height of 146 short children with either nonacquired GH deficiency or idiopathic short stature. Our purpose was 1) to assess growth according to the pituitary magnetic resonance imaging findings in the 63 GH-treated children with GH deficiency and 2) to compare the growth of the GH-deficient patients with normal magnetic resonance imaging (n = 48) to that of 32 treated and 51 untreated children with idiopathic short stature (GH peak to provocative tests >10 microg/liter). The mean GH dose was 0.44 IU/kg.wk (0.15 mg/kg.wk), given for a mean duration of 4.6 yr. Among the GH-deficient children, 15 had hypothalamic-pituitary abnormalities (stalk agenesis), all with total GH deficiency (GH peak <5 microg/liter). They were significantly shorter and younger at the time of diagnosis than those with normal magnetic resonance imaging, had better catch-up growth (+2.7 +/- 0.9 vs. +1.3 +/- 0.8 SD score; P < 0.01), and reached greater final height (-1.1 +/- 1.0 vs. -1.7 +/- 1.0 SD score; P < 0.05). Among patients with normal magnetic resonance imaging, there was no difference in catch-up growth and final height between partial and total GH deficiencies. GH-deficient subjects with normal magnetic resonance imaging and treated and untreated patients with idiopathic short stature had comparable auxological characteristics, age at evaluation, and target height. Although they had different catch-up growth (+1.3 +/- 0.8, +0.9 +/- 0.6, and +0.7 +/- 0.9 SD score, respectively; P < 0.01, by ANOVA), these patients reached a similar final height (-1.7 +/- 1.0, -2.1 +/- 0.8, and -2.1 +/- 1.0 SD score, respectively; P = 0.13). Pituitary magnetic resonance imaging findings show the heterogeneity within the group of nonacquired GH deficiency and help to predict the response to GH treatment in these patients. The similarities in growth between the GH-deficient children with normal magnetic resonance imaging and those with idiopathic short stature suggest that the short stature in the former subjects is at least partly due to factors other than GH deficiency.     

Serum ghrelin levels are suppressed in hypopituitary patients following insulin-induced hypoglycaemia irrespective of GH status

OBJECTIVE: Circulating ghrelin is suppressed during insulin-induced hypoglycaemia in healthy subjects, but it is unknown whether this is determined by feedback inhibition from counter-regulatory hormones. We therefore investigated the impact of GH and cortisol on ghrelin secretion during insulin-induced hypoglycaemia. DESIGN: Serum levels of ghrelin, GH, and cortisol were measured in 41 adult patients with suspected hypopituitarism during insulin-induced hypoglycaemia. Based on their peak GH response (cut-off level: 3 microg/l), the patients were divided into a GH-sufficient group (GHS) and a GH-deficient group (GHD). RESULTS: The GHS patients (n = 16) were younger (P < 0.01), had lower baseline cortisol levels [255 +/- 37 vs. 372 +/- 38 nmol/l (P = 0.04)], and tended to have a lower body mass index (P = 0.09) as compared to GHD patients (n = 25). By definition, peak GH (microg/l) was higher in GHS patients [15.0 +/- 1.8 vs. 1.0 +/- 0.2 (P < 0.0001)].The increase in serum cortisol during the ITT (insulin-tolerance test) was higher and occurred later in GHS patients [Cmax (nmol/l): 561 +/- 41 vs. 412 +/- 50 (P = 0.04); Tmax (minutes): 65 +/- 5 vs. 49 +/- 5 (P = 0.03)]. Serum ghrelin levels changed significantly with time during ITT in both groups (P < 0.0001), characterized by a moderate decline during the initial 50-60 min and a return to baseline after 2 h. No significant differences were recorded in AUCghrelin during the ITT between the two groups. No gender differences in ghrelin levels were recorded. CONCLUSIONS: (i) Like in healthy subjects serum ghrelin levels are suppressed during an ITT in patients with suspected hypopituitarism. (ii) The suppression of ghrelin was similar in GHD and GHS subjects and was not determined by cortisol. (iii) We hypothesize that insulin rather than hypoglycaemia accounts for ghrelin suppression during an ITT.     

Common carotid intima-media thickness in growth hormone (GH)-deficient adolescents: a prospective study after GH withdrawal and restarting GH replacement

We prospectively investigated the risk of early atherosclerosis, by classical cardiovascular risk factors and intima-media thickness (IMT) at the common carotid arteries, in 23 adolescents diagnosed as GH deficient (GHD) during childhood and in 23 healthy sex-, age-, and BMI-matched controls. Measurements were performed in all subjects before stopping GH replacement. Because the diagnosis of GHD had been confirmed in 15 of the 23 adolescents, the protocol changed according to the diagnosis as follows: measurements were repeated after 6 months of GH withdrawal and 6 months of GH reinstitution in the 15 with GHD, and after 6 and 12 months of GH withdrawal, measurements were also taken in the eight non-GHD subjects. Serum IGF-I levels were in the normal range for age in all patients before GH withdrawal. When compared with controls, before GH withdrawal, GHD adolescents had reduced high-density lipoprotein cholesterol levels and increased total/high-density lipoprotein cholesterol ratio, fibrinogen, low-density lipoprotein cholesterol, and glucose levels; non-GHD adolescents had increased glucose, insulin, and homeostasis model assessment score. IMT at the common carotid arteries was similar in GHD and controls (0.52 +/- 0.03 vs. 0.55 +/- 0.06 mm; P = 0.23) and was higher in non-GHD than in controls (0.62 +/- 0.03 vs. 0.54 +/- 0.06 mm; P = 0.01). In GHD adolescents, 6 months of GH treatment withdrawal and 6 months of GH treatment reinstitution modified IGF-I levels, lipid profile, and insulin resistance but not IMT or systolic and diastolic peak velocities at the common carotid arteries. In non-GHD subjects, 12 months of GH treatment withdrawal significantly decreased IGF-I levels, IMT (to 0.54 +/- 0.06 mm; P < 0.001 vs. baseline), systolic and diastolic peak velocities, and improved insulin resistance. In conclusion, the discontinuation of GH in confirmed GHD adolescents is not followed by significant alterations of the common carotid arteries, despite the profound negative alterations of the lipid profile. In adolescents who were not confirmed to have GHD, IMT was increased while on GH therapy and normalized when they were taken off of GH.     

Atherogenic lipoprotein phenotype and low-density lipoprotein size and subclasses in patients with growth hormone deficiency before and after short-term replacement therapy

OBJECTIVE: Patients with growth hormone deficiency (GHD) have increased cardiovascular risk and may show elevated triglyceride and reduced high density lipoprotein (HDL) cholesterol concentrations, two lipid abnormalities usually accompanied by increased small dense LDL in the 'atherogenic lipoprotein phenotype' (ALP). In the present study, we directly investigated (1) whether hypopituitary patients with GHD have increased small dense LDL; (2) whether growth hormone replacement therapy (GHRT) beneficially impact on such particles; (3) the prevalence of ALP in GHD and GHRT patients. DESIGN AND METHODS: In 14 hypopituitary patients with GHD (44 +/- 13 years, body mass index (BMI) 27 +/- 3) before and after 4 months of GHRT, and in 11 healthy age- and BMI-matched controls we measured plasma lipids and LDL size and subclasses by gradient gel electrophoresis. RESULTS: Compared with controls, GHD showed increased triglycerides (P = 0.0024), similar total and LDL cholesterol levels and a tendency towards reduced HDL cholesterol concentrations (P = 0.0894). GHRT reduced total and LDL cholesterol levels (P = 0.0303 and 0.0120 respectively), but no effect was found on triglycerides and HDL cholesterol levels. LDL size was unchanged in GHD versus controls (269 +/- 9 vs 274 +/- 6 A, P = ns), but LDL subclass analysis revealed a shift towards more dense particles (P = 0.0046). GHRT had no significant impact on LDL size and subclasses. The prevalence of ALP was 14% in GHD and 7% in GHRT. CONCLUSIONS: In GHD patients, individual features of ALP (including increased small dense LDL) may be common, but complete ALP is relatively uncommon. Short-term replacement therapy seems to be ineffective on such lipid alterations, but the effect of a longer GHRT remains to be assessed.