Conventional pituitary irradiation is effective in lowering serum growth hormone and insulin-like growth factor-I in patients with acromegaly

BACKGROUND: There has been recent controversy as to the effectiveness of conventional pituitary irradiation in reducing circulating GH levels to less than 2.5 ng/ml and/or normalization of serum IGF-I. OBJECTIVES: Our objectives were to determine the effects of conventional pituitary irradiation on 1) lowering of serum GH and IGF-I levels, 2) the proportion of patients who achieve a GH level less than 2.5 ng/ml and a normal age-corrected IGF-I and the time taken to achieve this, and 3) the incidence of hypopituitarism and other adverse effects. DESIGN: We conducted retrospective data collection from 14 centers throughout the United Kingdom. PATIENTS: We studied 1840 patients with acromegaly, of whom 884 had received conventional pituitary irradiation. MEASUREMENTS: We assessed circulating GH and IGF-I levels and pituitary function at intervals after irradiation. RESULTS: Mean GH levels declined from 13.5 to 5.3 ng/ml at 2 yr after irradiation, to 2.0 ng/ml by 10 yr, and to 1.1 ng/ml at 20 yr. Twenty-two percent of patients achieved a level less than 2.5 ng/ml by 2 yr, 60% by 10 yr, and 77% by 20 yr. The interval to achieve this depended on the preirradiation GH level. IGF-I levels fell in parallel to those of GH with 63% of patients having a normal level by 10 yr. The proportions of patients with new pituitary hormone deficiencies 10 yr after irradiation were 18% for LH/FSH, 15% for ACTH, and 27% for TSH. No other side effects were noted. CONCLUSIONS: In this, the largest series reported, conventional pituitary irradiation is shown to be an effective and safe means of reducing both serum GH and IGF-I concentrations in patients with acromegaly.     

Assessment of GH status in acromegaly using serum growth hormone, serum insulin-like growth factor-I and urinary growth hormone excretion

OBJECTIVE It Is still not clear what Is the most suitable method for monitoring progress of acromegaly. The aim of this study was to assess the relative merits of serum GH, serum IGF-I and urinary GH (uGH) excretion in the follow-up of acromegalic subjects. SUBJECTS AND METHODS Thirty-six acromegalic patients each had a GH day series performed consisting of five serum GH measurements, together with an estimate of serum IGF-I and uGH. The first sample taken for serum GH was fasting (basal) whilst the third (1430 h) was arbitrarily chosen as a random value. uGH was measured from two overnight collections and the mean value used for subsequent data analysis. MEASUREMENTS Serum GH and IGF-I were measured by radioimmunoassay whilst uGH was estimated by an Immunoradlometric assay using commercially available reagents. RESULTS There is a highly significant linear correlation between serum GH and IGF-I following log transformation of these two variables (r=0.85; P<0.0001). Analysis of the raw data shows that the relation is in fact curvilinear rendering IGF-I less useful as a surrogate for Integrated GH secretion at high levels of serum GH. There is a strong linear correlation between both a singleton basal serum GH and uGH (r=0.78; P<0001) and the mean of five measurements (day series) and uGH (r=0.81; P<0.0001). Both uGH and IGF-I are excellent predictors of those patients with persistent elevation of serum GH, identifying 95 and 96% respectively with serum GH>5mU/l. We have identified a number of patients, however, with persistent elevation of IGF-I in the presence of serum GH<5mU/l and normal uGH. Until the significance of these findings with respect to long-term outcome is known, serum GH should continue to be used In the follow-up of these patients. An alternative, which reflects integrated overnight GH secretion, Is uGH which is convenient and easy to collect as an outpatient and correlates strongly with serum GH. CONCLUSION Acromegalic patients can be conveniently followed on an outpatient basis using a combination of uGH and serum IGF-I. Measurements of serum GH can be reserved for those with discrepant results.     

Alternate-day administration of pegvisomant maintains normal serum insulin-like growth factor-I levels in patients with acromegaly

IGF-I levels normalize in the majority of patients with acromegaly treated with the GH receptor antagonist pegvisomant. To date, the efficacy of pegvisomant has been demonstrated with daily administration of doses ranging from 10 to 40 mg. However, given the known long half-life of the drug in circulation, we hypothesized that dosing less frequently than daily would still maintain the drug's efficacy. We studied 10 patients with active acromegaly treated with pegvisomant. This therapy was begun at 10 mg daily but then titrated up in dose or down to alternate-day dosing to try to maintain serum IGF-I levels in the upper half of the patients' age-adjusted normal range. We found that in five of 10 patients, serum IGF-I levels remained normal on less frequent than daily pegvisomant. Signs and symptoms of the disease and a disease-related morbidity, insulin resistance, remained improved in these patients. We demonstrate for the first time the continued efficacy of alternate-day administration of pegvisomant.     

Roles of insulin-like growth factor-I and growth hormone in mediating insulin resistance in acromegaly

Most patients with acromegaly have some degree of insulin resistance. The principal mediator of insulin resistance in acromegaly is hypersecretion of growth hormone. Growth hormone acts at several levels to block insulin actions including inhibiting phosphorylation of the insulin receptor and one of its principal signaling molecules IRS-1 in response to insulin administration. This leads to reduced sensitivity to insulin in the periphery in stimulating peripheral glucose uptake and to increased resistance to insulin's ability to suppress gluconeogenesis. Furthermore growth hormone excess leads to mobilization of free fatty acids which inhibit insulin stimulated glucose oxidation by acting as a competitive energy source thus leading to further worsening of insulin resistance. These abnormalities can be overcome by administering agents which either lower growth hormone secretion or block growth hormone action. The role of elevated IGF-I in acromegaly in mediating insulin resistance is more difficult to analyze. Indirect inferences from the data that are available suggest that IGF-I is acting to enhance insulin sensitivity and partially counteracting the insulin antagonistic effects of growth hormone. In a recent study administration of IGF-I to acromegalics was shown to improve insulin sensitivity over and above the level that could be achieved by simply blocking growth hormone action. Therefore it appears that the net effect of IGF-I is to counterbalance some of the effects of growth hormone hypersecretion on insulin resistance.     

Lower visceral and subcutaneous but higher intermuscular adipose tissue depots in patients with growth hormone and insulin-like growth factor I excess due to acromegaly

CONTEXT: GH and IGF-I are important regulators of metabolism and body composition. In acromegaly, a state of GH and IGF-I excess, the lipolytic and insulin antagonistic effects of GH may alter adipose tissue (AT) distribution. OBJECTIVES: Our objective was to test the hypothesis that in acromegaly whole-body AT mass is less and to examine for the first time the relationship between GH/IGF-I excess and intermuscular AT (IMAT), an AT depot associated with insulin resistance in other populations. DESIGN, SETTING, AND PATIENTS: We conducted a cross-sectional study in 24 adults with active acromegaly compared with predicted models developed in 315 healthy non-acromegaly subjects. OUTCOME MEASURES: Mass of AT in the visceral AT (VAT), sc AT (SAT), and IMAT compartments from whole-body magnetic resonance imaging and serum levels of GH, IGF-I, insulin, and glucose were measured. RESULTS: VAT and SAT were less in active acromegaly (P < 0.0001); these were 68.2 +/- 27% and 79.5 +/- 15% of predicted values, respectively. By contrast, IMAT was greater (P = 0.0052) by 185.6 +/- 84% of predicted. VAT/trunk AT ratios were inversely related to IGF-I levels (r = 0.544; P = 0.0054). Acromegaly subjects were insulin resistant. CONCLUSIONS: VAT and SAT, most markedly VAT, are less in acromegaly. The proportion of trunk AT that is VAT is less with greater disease activity. IMAT is greater in acromegaly, a novel finding, which suggests that increased AT in muscle could be associated with GH-induced insulin resistance. These findings have implications for understanding the role of GH in body composition and metabolic risk in acromegaly and other clinical settings of GH use.     

Effective clinical response to long term octreotide treatment, with reduced serum concentrations of growth hormone, insulin-like growth factor-I, and the amino-terminal propeptide of type III procollagen in acromegaly

Ten patients with active acromegaly, six with a poor response to previous therapies and four newly diagnosed, were treated with the long-acting somatostatin analog octreotide (Sandostatin; 200-500 micrograms/day, sc, twice or three times daily) for 6-15 months. There was rapid clinical improvement in all patients. The mean daily serum GH concentration was reduced by 64% and was normalized (all GH values less than 2 micrograms/L) in three patients. Serum insulin-like growth factor-I (IGF-I) concentrations were lowered by 40% and were normalized in eight patients. Serum concentrations of the amino-terminal propeptide of type III procollagen (PIIINP), an index of tissue collagen metabolism, were reduced by 40% and were normalized in all patients with initially elevated values. There was a statistically significant positive correlation between the mean serum GH and IGF-I levels (r = 0.47; P less than 0.001) as well as between serum GH and PIIINP levels (r = 0.34; P less than 0.05) and between serum IGF-I and PIIINP (r = 0.50; P less than 0.001). The effects of octreotide on pituitary tumor size and pathology were evaluated in one patient. The therapy did not seem to be associated with significant changes in sellar computed tomographic scans or light microscopic findings. The drug was generally well tolerated. However, indications of significant hepato-biliary dysfunction were noted in one patient after 5 months of therapy. This was reversible upon discontinuation of therapy and did not occur later during the rechallenge with a lower dose of the drug. However, there was probably newly formed cholelithiasis in four patients during the therapy. Our study suggests that octreotide is an effective and relatively safe new approach for treating active acromegaly. Further studies are needed to investigate long term effects on the hepatobiliary system.     

Plasma insulin-like growth factor-I/somatomedin-C in acromegaly: correlation with the degree of growth hormone hypersecretion

We measured plasma insulin-like growth factor I/somatomedin-C (IGF-I/SmC) concentrations and mean 24-h GH secretion serially before and during therapy with the long-acting somatostatin analog SMS 201-995 in 21 patients with acromegaly. When mean plasma GH was elevated above 12.0 +/- 0.6 (+/- SE) micrograms/L, plasma IGF-I/SmC concentrations were uniformly high, but a decline of mean plasma GH below this value was accompanied by a linear decrease in IGF-I/SmC concentrations (r = 0.89; P less than 0.001). Even mildly abnormal mean GH concentrations (greater than 4.6 but less than 10 micrograms/L) were accompanied by high plasma IGF-I/SmC values. The log dose-response interrelation between mean 24-h plasma GH and IGF-I/SmC concentrations was linear (r = 0.86; P less than 0.001). We conclude that 1) an excellent log dose-response correlation between mean 24-h plasma GH and IGF-I/SmC concentrations is present in patients with acromegaly; 2) normalization of plasma IGF-I/SmC occurs only in patients with mean daily GH output within the normal range; and 3) determination of plasma IGF-I/SmC is an accurate indicator of normalcy of GH secretion and should be used in the diagnosis of active acromegaly as well as in monitoring the progress of therapy.     

Pegvisomant-induced serum insulin-like growth factor-I normalization in patients with acromegaly returns elevated markers of bone turnover to normal

Active acromegaly is associated with increased biochemical markers of bone turnover. Pegvisomant is a GH receptor antagonist that normalizes serum IGF-I in 97% of patients with active acromegaly. We evaluated the effects of pegvisomant-induced serum IGF-I normalization on biochemical markers of bone and soft tissue turnover, as well as levels of PTH and vitamin D metabolites, in 16 patients (nine males; median age, 52 yr; range, 28-78 yr) with active acromegaly (serum IGF-I at least 30% above upper limit of an age-related reference range). Serum procollagen III amino-terminal propeptide (PIIINP) and type I procollagen amino-terminal propeptide, osteocalcin (OC), bone-related alkaline phosphatase, C-terminal cross-linked telopeptide of type I collagen (CTx), albumin-corrected calcium, intact PTH, 25-hydroxy vitamin D, 1,25-dihydroxy vitamin D [1,25-(OH)(2) vit D], urinary type 1 collagen cross-linked N-telopeptide/creatinine ratio, and urinary calcium (24 h collection) were measured (single-batch analysis) at study entry and after IGF-I normalization, along with sera from 32 age- and sex-matched controls. Compared with controls, PIIINP, OC, and CTx were significantly elevated in patients at baseline. Pegvisomant-induced serum IGF-I normalization (699 +/- 76 to 242 +/- 28 micro g/liter, P < 0.001) was associated with a significant decrease in PIIINP, markers of bone formation (type I procollagen amino-terminal propeptide, OC, and bone-related alkaline phosphatase), and resorption (CTx and urinary type 1 collagen cross-linked N-telopeptide/creatinine ratio). 1,25-(OH)(2) vit D decreased and intact PTH increased significantly, but 25-hydroxy vitamin D was unaffected. A significant decline in calculated calcium clearance was observed. The decrease in serum IGF-I correlated positively with the decrease of serum PIIINP (r = 0.7, P < 0.01). After normalization of serum IGF-I, there was no statistical difference between patients and controls for any parameters for which control data were available. In conclusion, GH excess is associated with increased bone and soft tissue turnover. Pegvisomant-induced normalization of serum IGF-I results in a decrease in markers of bone and soft tissue turnover to levels observed in age-matched controls, and these changes are accompanied by an increase in PTH and a decrease in 1,25-(OH)(2) vit D. These data provide further evidence of the effectiveness of pegvisomant in normalizing the altered biological effects of GH hypersecretion.     

Divergence between growth hormone and insulin-like growth factor-i concentrations in the follow-up of acromegaly

CONTEXT: Divergence between GH and IGF-I values is regularly observed in treated acromegalic patients, and its significance is unclear. OBJECTIVES: The objective of the study was to explore the frequency and identify potential determinants of discordant serum GH and IGF-I concentrations in noncured acromegalic patients. PATIENTS: Two hundred twenty-nine noncured acromegalic patients of the Belgian acromegaly registry (AcroBel) were grouped according to their mean GH level (< or = or > 2 microg/liter) and IGF-I z-score (< or = 2 or > 2). Clinical and metabolic parameters were compared between groups with active disease (high GH and IGF-I; n=81),high GH (with normal IGF-I; n=25), high IGF-I (with normal GH; n=55), and controlled disease (GH and IGF-I normal; n=68). RESULTS: Compared with the high IGF-I group, the high GH group was characterized by younger age (52 vs. 58 yr, P < 0.05), female predominance (72 vs. 36%, P < 0.01), and lower body mass index (25 vs. 31 kg/m(2); P < 0.001), fasting glucose (91 vs. 99 mg/dl; P < 0.05), and glycated hemoglobin levels (5.7 vs. 6.1%; P < 0.01). There was no difference among the groups regarding baseline characteristics of pituitary adenoma, current medical treatment, or symptom score. CONCLUSIONS: Thirty-five percent of noncured acromegalic patients exhibit a discordant GH and IGF-I pattern. The high GH phenotype was found predominantly in younger estrogen-sufficient females, implying a possible role for age, gender, and estrogens in this biochemical divergence. The high IGF-I phenotype was associated with a worse metabolic profile, suggesting that high IGF-I, rather than high GH, is indicative of persistently active disease.     

Serum growth hormone-binding protein, insulin-like growth factor-I, and growth hormone in patients with liver cirrhosis.

We determined serum growth hormone-binding protein (GHBP), insulin-like growth factor-I (IGF-I), and growth hormone (GH) levels in patients with cirrhosis and in age-matched control subjects, and investigated their relationships. Serum GHBP levels in cirrhotic patients (14.6% +/- 3.9%) (means +/- SD) were significantly lower than those in normal subjects (20.4% +/- 4.7%). GHBP levels had positive correlations with cholinesterase (r = .58, P less than .001) and Normotest (r = .66, P less than .001), both of which represent liver function in cirrhotic patients. Basal GH levels in cirrhotic patients (range, 0.35 to 13.0 micrograms/L; median, 3.9 micrograms/L) were significantly higher than those in normal subjects (0.015 to 6.0 micrograms/L; 0.19 microgram/L). GHBP levels in cirrhotic patients correlated positively with IGF-I levels (r = .39, P less than .01), and negatively with GH levels (r = -.33, P less than .01). These results may indicate that the serum GHBP level reflects the number of hepatic GH receptors, and that the high basal GH level observed in cirrhotic patients is, at least in part, attributable to decreased clearance of GH by these receptors.     

Growth hormone (GH) receptor blockade with a PEG-modified GH (B2036-PEG) lowers serum insulin-like growth factor-I but does not acutely stimulate serum GH.

B2036-PEG, a GH receptor (GH-R) antagonist, is an analog of GH that is PEG-modified to prolong its action. Nine mutations alter the binding properties of this molecule, preventing GH-R dimerization and GH action. A potential therapeutic role of B2036-PEG is to block GH action, e.g. in refractory acromegaly. A phase I, placebo-controlled, single rising-dose study was performed in 36 normal young men (ages, 18-37 yr; within 15% ideal body weight). Four groups received a single s.c. injection of either placebo (n = 3 in each group, total n = 12) or B2036-PEG (0.03, 0.1, 0.3, or 1.0 mg/kg; n = 6 each dose). B2036-PEG and GH concentrations were measured 0, 0.25, 0.5, 1, 3, 6, 9, 12, 24, 36, 48, 72, 96, 120, and 144 h after dosing. Serum insulin-like growth factor-I was measured before and 1-7 days after dosing. All doses were well tolerated, with no serious or severe adverse reactions. B2036-PEG, at 1.0 mg/kg, reduced insulin-like growth factor-I by 49 +/- 6% on day 5 (P < 0.001 vs. placebo). GH was measured by two independent methods: 1) modified Nichols chemiluminescence assay (empirically corrected for B2036-PEG cross-reactivity); and 2) direct GH two-site immunoassay, using monoclonal antibodies that did not react with B2036-PEG. There was good agreement between the two methods. GH did not change substantially at any B2036-PEG dose, suggesting that B2036-PEG does not interact with hypothalamic GH-Rs to block short-loop feedback. B2036-PEG may thus block peripheral GH action without enhancing its secretion.     

Effects of growth hormone therapy on the developmental changes of follicle stimulating hormone and insulin-like growth factor-I serum concentrations in Turner's syndrome

OBJECTIVE The aim was to investigate whether, in the absence of gonads, GH could bring forward the age of neuroendocrine activation resulting in onset of puberty. DESIGN In girls with Turner's syndrome, we evaluated the effects of GH therapy on developmental changes in FSH serum concentrations used as an indicator of neuroendocrine maturation in the absence of gonads. PATIENTS Thirty-nine girls with Turner's syndrome aged 4.0-17.1 years were treated using GH (25 IU/m² week) for 1 year. MEASUREMENTS Serum levels of FSH and IGF-I were measured before initiation of GH therapy and 12 months later, after interruption of GH treatment for 2 days. RESULTS Pretreatment FSH levels were low between 6 and 10 years and increased markedly at 10-11 years of age. This pattern was unchanged after 1 year of GH therapy. Pretreatment IGF-I levels were positively correlated with age and they were uniformly increased after 1 year of GH therapy. CONCLUSIONS Our data suggest that GH and its effector, IGF-I, do not influence the timing of the onset of puberty through an effect on its neuroendocrine control.     

Treatment with growth hormone and insulin-like growth factor-I in critical illness

The wider availability of recombinant human growth hormone and insulin-like growth factor-I has resulted in an investigation into the potential benefits of the pharmacological administration of these anabolic peptides in a variety of clinical conditions, characterized by an increase in catabolic rate. The initial studies were small, often uncontrolled open investigations, but investigators have more recently concentrated on larger, controlled multi-centre trials. Studies to date have included patients with cardiac failure, sepsis, burns, cancer cachexia, end-stage renal failure, trauma and AIDS, and those prior to or following major surgery. The authors have in general cautiously interpreted positive effects of treatment with growth hormone and insulin-like growth factor-I, either alone or in combination, on net protein balance, body composition, well-being and performance. Two large, randomized, placebo-controlled European multi-centre studies have recently detailed the effects of growth hormone treatment in critically ill intensive care patients. Major increases in mortality and morbidity were associated with growth hormone treatment. The mechanism(s) accounting for the increased mortality remain poorly understood. These negative findings have led to a decrease in the clinical use of growth hormone and in research activity in the area of anabolic treatment in human illness.     

Serum concentrations of insulin-like growth factor-I and insulin-like growth factor binding protein-3 in patients with chronic hepatitis

BACKGROUND: Insulin-like growth factor-I is a liver-derived humoral factor, which has important anabolic and metabolic actions and is predominantly bound by insulin-like growth factor binding protein-3. Low serum concentrations of both insulin-like growth factor-I and insulin-like growth factor binding protein-3 have been reported in patients with chronic liver disease, especially cirrhosis, but their conditions in chronic hepatitis are uncertain. The aim of this study was to evaluate the effect of chronic hepatitis on serum concentrations of insulin-like growth factor-I and insulin-like growth factor binding protein-3 and their association with hepatic inflammation activity and fibrosis. METHODS: Serum insulin-like growth factor-I and insulin-like growth factor binding protein-3 were measured by RIA (ng/ml) in 17 patients with mild to severe chronic viral hepatitis (12 chronic hepatitis C, 5 chronic hepatitis B) and 16 healthy subjects. The hepatic inflammation activity and the severity of fibrosis were evaluated using Desmet classification. RESULTS: Both insulin-like growth factor-I and insulin-like growth factor binding protein-3 levels did not correlate with inflammation activity, fibrosis or transaminase levels. In the chronic hepatitis group, insulin-like growth factor-I levels were significantly higher than the control group (mean, 263.8 +/- 27.33 versus 127.14 +/- 10.83 ng/ml, P < 0.001, respectively), whereas insulin-like growth factor binding protein-3 levels were significantly lower when compared with the controls (1643.47 +/- 60.68 versus 2728.87 +/- 284.61 ng/ml, P < 0.05, respectively). CONCLUSIONS: These results suggest that the concomitant states of serum insulin-like growth factor-I and insulin-like growth factor binding protein-3 levels in patients with chronic hepatitis may be different from cirrhotic patients and high serum IGF-I levels may be a specific finding of the stage of chronic hepatitis before developing cirrhosis.     

Relationship between insulin-like growth factor-I and brain natriuretic peptide in patients with acromegaly after surgery.

BACKGROUND: Increased cardiac insulin-like growth factor (IGF)-I production is associated with physiological cardiac hypertrophy in athletes, and IGF-I has been recognized as a cardioprotective agent in experimental animal studies. On the other hand, acromegaly which is characterized by an excess of IGF-I has been linked to impaired cardiac function. METHODS AND RESULTS: Both the relationship between the serum levels of IGF-I and brain natriuretic peptide (BNP), which is released from the cardiac ventricles in response to ventricular stress, and that between IGF-I and the concentrations of the plasma amino-terminal propeptide of procollagen type III (P-III-P), which is associated with myocardial fibrosis, were evaluated in 19 patients after surgical treatment for acromegaly. Echocardiography revealed that left ventricular systolic function and dimensions were within normal range in all patients. Significant inverse correlations were found between IGF-I and the BNP (r=-0.5, p=0.02) and P-III-P levels (r=-0.62, p=0.005). CONCLUSION: We observed an inverse significant relationship between IGF-I and both the BNP and P-III-P value in surgically treated acromegaly patients. These observations suggest that appropriate levels of IGF-I have beneficial cardioprotective effects after surgery in patients with acromegaly.     

Growth hormone and insulin-like growth factor-1 concentrations in women with fibromyalgia

OBJECTIVE: To determine activity of the growth hormone-insulin-like growth factor-1 (GH-IGF-1) axis in women with fibromyalgia (FM). METHODS: Premenopausal women with FM (n = 24) and premenopausal healthy women (n = 27) were studied. IGF-1 was measured in 23 patients with FM and 25 controls. GH was measured during a stepped hypoglycemic hyperinsulinemic clamp procedure (blood glucose decreased from 90 to 40 mg/dl every 30 min in 10 mg/dl decrements) in 12 FM and 13 control subjects. RESULTS: IGF-1 concentrations were similar in the FM (200 +/- 71 ng/ml, mean +/- SD) and control (184 +/- 70 ng/ml) groups. By multiple variable analysis, IGF-1 was negatively associated with age (p = 0.0006), body mass index (BMI) (p = 0.006), and 24 h urinary free cortisol (p = 0.007) in healthy controls. Even after accounting for these factors, there was no association between FM and IGF-1. The average peak GH achieved during hypoglycemia was lower in patients with FM (range 5 to 58 ng/ml, median 13 ng/ml) versus controls (6 to 68 ng/ml, median 21 ng/ml) (p = 0.04). However, BMI was a significant predictor of average peak GH in FM (r = -0.62, p < 0.01) and control subjects (r = -0.40, p = 0.06). After considering BMI, there was no significant association between FM subjects and the average peak GH (p = 0.20). CONCLUSION: In this sample of premenopausal women with FM, the activity of the GH-IGF-1 axis was similar to that of healthy controls. Increases in age and obesity were both strongly associated with lower activity of this axis, suggesting that these factors must be considered when studying activity of the GH-IGF-1 axis in FM.     

Secretion of growth hormone-releasing hormone in patients with idiopathic pituitary dwarfism and acromegaly

The plasma levels of immunoreactive-GHRH in patients with idiopathic pituitary dwarfism and acromegaly were studied in the basal state and during various tests by a sensitive and specific RIA. The fasting plasma GHRH level in 22 patients with idiopathic pituitary dwarfism was 6.3 +/- 2.3 ng/l (mean +/- SD), which was significantly lower than that in normal children (9.8 +/- 2.8 ng/l, N = 21), and eight of them had undetectable concentrations (less than 4.0 ng/l). Little or no response of plasma GHRH to oral administration of L-dopa was observed in 7 of 10 pituitary dwarfs, and 3 of the 7 patients showed a response of plasma GH to iv administration of GHRH (1 microgram/kg). These findings suggest that one of the causes of idiopathic pituitary dwarfism is insufficient GHRH release from the hypothalamus. The fasting plasma GHRH level in 14 patients with acromegaly and one patient with gigantism was 8.0 +/- 3.9 ng/l, which was slightly lower than that in normal adults (10.4 +/- 4.1 ng/l, N = 72). One acromegalic patient with multiple endocrine neoplasia type I had a high level of plasma GHRH (270 ng/l) with no change in response to L-dopa and TRH test. In 3 untreated patients with acromegaly L-dopa did not induce any response of plasma GHRH in spite of inconsistent GH release, and in 4 patients with acromegaly, TRH evoked no response of plasma GHRH in spite of a marked GH release, suggesting that the GH responses are not mediated by hypothalamic GHRH.(ABSTRACT TRUNCATED AT 250 WORDS)     

Transient elevation of serum growth hormone level during pituitary apoplexy in acromegaly

We report a case of acromegaly followed by pituitary apoplexy in which hormonal changes during the course of an acute episode were investigated. Serum growth hormone level increased markedly during the acute phase, and, subsequently, decreased rapidly. Finally, serum growth hormone level remained low and did not respond to stimulation. In contrast, the serum cortisol level remarkably decreased during the most serious stage and returned to the previous level after pituitary apoplexy. The low level of cortisol during the acute phase is compatible with the patient's manifestation of adrenal insufficiency, and hydrocortisone sodium succinate administration improved the critical state of the patient dramatically.