Increased melatonin concentrations in children with growth hormone deficiency

A relationship between melatonin and growth hormone (GH) is poorly understood. We compare circadian melatonin rhythms in short children with normal and decreased GH secretion. The analysis included 22 children (20 boys and 2 girls) aged 11.1-16.9 yr (mean +/- S.E.M. = 14.1 +/- 0.3 yr) with short stature (height SDS below -2.0). Based on the GH peak in stimulation tests patients were divided into two groups: idiopathic short stature (ISS, n = 11; GH peak > or = 10 ng/mL) and GH deficiency (GHD, n = 11; GH peak < 10 ng/mL). In all patients the circadian melatonin rhythm was assessed on the basis of nine blood samples, collected in 4-hr intervals during the daytime and 2-hr intervals at night, with dark period lasting from 22:00 to 06:00 hr. Magnetic resonance imaging examination excluded organic abnormalities in central nervous system in all patients. Melatonin concentration at 24:00, 02:00 and 04:00 hr as well as the area under curve of melatonin concentrations (AUC) were significantly higher in the patients with GHD than in individuals with ISS. Significant correlations between GH secretion and melatonin concentrations at 24:00, 02:00 and 04:00 hr, and AUC were also observed. On the basis of these data it seems that the assessment of nocturnal melatonin secretion might be a valuable diagnostic tool used for the improvement of the difficult diagnosis of short stature in children.     

Short children with familial short stature show enhancement of somatotroph secretion but normal IGF-I levels

The aim of the present study was to evaluate the GH status in children with familial, idiopathic short stature (FSS). To this goal we evaluated the GH response to GHRH (1 microg/kg iv) + arginine (ARG) (0.5 g/kg iv) test which is one of the most potent and reproducible provocative tests of somatotroph secretion, in 67 children with FSS [50 boys and 17 girls, age 10.8+/-0.4 yr, pubertal stages I-III, height between -3.6 and -1.6 standard deviation score (SDS), target height <10 degrees centile, normality of both spontaneous and stimulated GH secretion as well as of IGF-I levels]. The results in FSS were compared with those in groups of children of normal height (NHC) (42 NHC, 35 boys and 7 girls, age 12.0+/-0.5 yr, pubertal stages I-III, height between -1.3 and 1.4 SDS, height velocity standard deviation score (HVSDS)>25 degrees centile, GH peak >20 microg/l after GHRH+ARG test, mean GH concentration [mGHc]>3 microg/l) and children with organic GH deficiency (GHD) (38 GHD, 29 boys and 9 girls, age 11.2+/-3.7 yr, pubertal stages I-III, height between -5.7 and -1.3 SDS, GH peak <20 microg/l after GHRH +ARG test, mGHc <3 mg/l). Basal IGF-I levels and mGHc were also evaluated in each group over 8 nocturnal hours. IGF-I levels in FSS (209.2+/-15.6 microg/l) were similar to those in NHC (237.2+/-17.2 microg/l) and both were higher (p<0.0001) than those in GHD (72.0+/-4.0 microg/l). The GH response to GHRH +ARG test in FSS (peak: 66.4+/-5.6 microg/l) was very marked and higher (p<0.01) than that in NHC (53.3+/-4.5 microg/l) which, in turn, was higher (p<0.01) than in GHD (8.2+/-0.8 microg/l). Similarly, the mGHc in FSS was higher than in NHC (6.7+/-0.5 microg/l vs 5.1+/-0.7 microg/l, p<0.05) which, in turn, was higher than in GHD (1.5+/-0.2 microg/l, p<0.0001). In conclusion, our present study demonstrates that short children with FSS show enhancement of both basal and stimulated GH secretion but normal IGF-I levels. These findings suggest that increased somatotroph function would be devoted to maintain normal IGF-I levels thus reflecting a slight impairment of peripheral GH sensitivity in FSS.     

Near final height in pubertal growth hormone (GH)-deficient patients treated with GH alone or in combination with luteinizing hormone-releasing hormone analog: results of a prospective, randomized trial

To study the effects of delaying puberty in GH-deficient (GHD) children, we studied 21 GHD (9 boys, 14 girls), treatment-naive, pubertal patients in a prospective, randomized trial. Their chronological age was 14.3 +/- 1.6 yr, and their bone age was 11.3 +/- 1.1 yr (mean +/- SD) at the beginning of the study. Four patients who developed hypogonadotropic hypogonadism were subsequently excluded from the study. Patients were randomly assigned to receive GH + LH-releasing hormone analog (LHRH-A) (n = 7), or GH alone (n = 10). GH and LHRH-A treatment started simultaneously in each patient. GH (Nutropin) was administered at a dose of 0.1 U/kg x day sc, until patients reached a bone age (BA) of 14 yr in girls and 16 yr in boys, and LHRH-A (Lupron depot) was administered at a dose of 300 microg/ kg every 28 days in during 3 yr. We defined GH deficiency as patients with a growth velocity less than 4 cm/yr, BA delay more than 1 yr in relationship to chronological age, GH response to two stimulation tests less than 7 microg/L, associated with low serum insulin-like growth factor I and insulin-like growth factor binding protein 3 levels. Statistical analysis was performed by ANOVA or Kruskall Wallis when variances were not homogeneous. We observed a significant decrease in the rate of BA maturation in the group treated with GH+LHRH-A (1.5 +/- 0.2 yr) compared with the group treated with GH alone (4.2 +/-0.5 yr) during the 3 years of LHRH-A therapy (P < 0.05). This delay in BA maturation produced a significant gain in final height in the group treated with GH+LHRH-A, which reached - 1.3 +/- 0.5 SD score compared with -2.7 +/- 0.3 SD score (P < 0.05) in the group treated with GH alone. These results indicate that delaying puberty with LHRH-A in GHD children during treatment with GH increases final height.     

TNF-alpha levels in children with growth hormone deficiency and the effect of long-term growth hormone replacement therapy.

OBJECTIVE: Growth hormone (GH) has been suggested to modulate the release of some cytokines including TNF-alpha. To investigate TNF-alpha levels in children with GH deficiency (GHD), to evaluate alteration in TNF-alpha levels during recombinant human GH (rhGH) treatment, and to analyze possible correlations between TNF-alpha and GH, IGF-1 and IGFBP-3. DESIGN: Twenty-four children, aged 12.60+/-2.27 years, with isolated GHD and given rhGH therapy, as subcutaneous ingestion of 0.03-0.04mg/kg once-daily dose, were evaluated. Eleven had complete and 13 had partial GHD. Thirty-three healthy children were studied as controls. Age and sex distribution, body mass indexes of two groups were similar. In children with GHD, blood samples were drawn before (TNF-alpha0), and at 6 (TNF-alpha6) and 12 (TNF-alpha12) months of the treatment with rhGH. TNF-alpha was determined using a human TNF-alpha ELISA assay (Biosource International). RESULTS: TNF-alpha0 levels were significantly higher in children with GHD than in controls (41.79+/-25.04 and 8.63+/-4.48pg/ml, respectively, p<0.001) and decreased significantly during rhGH treatment (TNF-alpha0=41.79+/-25.04, TNF-alpha6=13.67+/-9.95, TNF-alpha12=10.86+/-6.61pg/ml, p<0.05). There was no correlation between TNF-alpha levels and BMI, IGF-1/logIGF1, IGFBP-3 levels and growth velocity of the patients with GHD. Although no correlation between TNF-alpha and peak GH levels after stimulation was present; a moderate reverse correlation between TNF-alpha and basal serum concentrations of GH (r=-0.512, p=0.046) was demonstrated. CONCLUSIONS: TNF-alpha levels are significantly higher in children with GHD than the controls, and long-term therapy with rhGH effectively reduces its level. Our data suggest that GH plays an inhibitory role on TNF-alpha release in humans. However, due to inconsistent results up to now, further prospective, controlled and long term studies are needed to elucidate the issue.     

Impairment of GH secretion in adults with primary empty sella

Primary empty sella (PES) is generally not associated with overt endocrine abnormalities, although mild hyperprolactinemia and, in children, deficient GH secretion have been reported. The aim of this multi-center collaborative study was to evaluate basal and stimulated GH secretion in a large series of adult PES patients. The study group consisted of 51 patients [41 women and 10 men, age range: 20-78 yr; (mean+/-SD) 47+/-11 yr]; results were compared with those in normal subjects (Ns) (Ns: no.=110, 55 women, age: 20-50 yr, 37+/-14 yr), and in hypopituitaric patients (HYP) with GH deficiency (HYP: no.=44,17 women, age: 20-72, 49+/-16 yr). Baseline IGF-I levels and GH responses to insulin-induced hypoglycemia (insulin tolerance test, ITT) and/or GHRH+arginine (ARG) stimulation tests were evaluated. PES patients were also subdivided according to BMI in lean (BMI <28 kg/M2 no.=22) or obese (BMI >28 kg/m2 no.=29). PES patients had serum total IGF-I concentrations (mean+/-SE: 142.2+/-9.6 ng/ml) higher than HYP patients (77.4+/-6.4 ng/ml, p<0.001), but lower than Ns (213.3+/-17.2 ng/ml, p<0.005), with no differences between lean and obese PES subjects. The increase in serum GH concentrations following ITT and/or GHRH+ARG stimulation tests, although higher than that observed in HYP patients, was markedly reduced with respect to Ns. No difference was observed in the GH response to provocative tests between lean and obese PES patients. When individual GH responses to ITT or GHRH+ARG were taken into account, a large proportion of PES patients (52% after ITT, 61% after GHRH+ARG) showed a GH peak increase below the 1st centile of normal limits. Serum IGF-I levels in PES patients with blunted GH responses to provocative tests were significantly (p<0.001) lower in PES patients with normal GH responses, and a positive correlation was observed between IGF-I levels and serum GH peak concentrations after GHRH+ARG. In conclusion, the results of the present study provide evidence that adult PES patients often have an impairment of GH secretion, as indicated by the blunted GH response to ITT and GHRH+ARG provocative tests, and by the reduction in serum IGF-I levels. These changes are independent of body mass.     

Growth hormone secretion in polytransfused prepubertal patients with homozygous beta-thalassemia. Effect of long-term recombinant GH (recGH) therapy

Growth was monitored in 133 male and 150 female North Sardinian prepubertal patients with homozygous beta-thalassemia in order to ascertain the incidence of GH deficiency (GHD) and the effects of long-term recombinant GH (recGH) treatment on growth velocity and bone maturation. A significant reduction in growth velocity and a fall in IGF-I levels was observed in 19 male and 16 female patients (12.3%). Their peak GH responses to GHRH (5.45+/-0.78 and 4.99+/-0.86 ng/ml) and clonidine administration (4.21+/-0.32 and 4.15+/-0.27 ng/ml in males and females, respectively) were markedly reduced with respect to control subjects (p<0.01). No statistically significant correlation was found between chronological age, number of blood units received, plasma ferritin levels and plasma IGF-I levels as well as with peak GH response to stimulation. Thalassemic patients with GHD had plasma ferritin levels (1382.44+/-160.34 and 1255.23+/-139.81 ng/ml in males and females, respectively) significantly lower than those recorded in the other patients (2848.94+/-283.61 and 3077.82+/-220.51 ng/ml). Patients with GHD were treated with recGH for an average period of 59 months (range 26-124). Treatment was able to restore growth and to increase significantly plasma IGF-I levels. Growth velocity at the end of the first yr of treatment was 6.78+/-1.21 and 6.11+/-0.85 cm/yr in males and females, respectively. Growth velocity values and plasma IGF-I levels remained significantly higher than basal values throughout the period of treatment. However, treatment was unable to normalize bone maturation since bone age values were always reduced with respect to chronological age. No incidence of side effects was observed. These data indicate that GHD, when present, is one but not the sole cause of delayed bone maturation and height deficiency in thalassemia.     

Impairment of GH responsiveness to GH-releasing hexapeptide (GHRP-6) in Prader-Willi syndrome.

The aim of this study was to evaluate the GH-releasing activity of a synthetic hexapeptide, GHRP-6, in the Prader-Willi syndrome (PWS). Sixteen PWS patients (7 males and 9 females, aged 12.7-38.3 yr), 15 with essential obesity (OB) (7 males and 8 females, aged 12.9-42.9 yr), and 8 short normal children (SN; 3 males and 5 females, aged 10.2-14.3 yr) underwent 2 tests on separate occasions, being challenged with GHRP-6 (1 microg/kg, iv) or GHRH (1 microg/kg, iv)+PD (60 or 120 mg for children or adults, po). Moreover, in 11 patients with PWS and in the group of SN, the GH response to at least 2 stimulation tests had been previously determined. GH was analyzed either as mean peak values (GHp, mcg/l), or as the area under the curve (AUC, mcg/l/h) and the net incremental area under the curve (nAUC, mcg/l/h). In the group of PWS subjects, GH responses to both GHRP-6 (GHp: 11.4+/-2.0; AUC: 588+/-113; nAUC: 483+/-108) and GHRH+PD (GHp: 7.3+/-1.8; AUC: 486+/-122; nAUC: 371+/-250) were significantly lower than those observed either in OB (GHRP-6: GHp: 25.7+/-3.2, p<0.003; AUC: 1833+/-305, p<0.005; nAUC: 1640+/-263, p<0.0001. GHRH+PD: GHp: 15.1+/-2.4, p<0.009; AUC: 1249+/-248, p<0.003; nAUC: 918+/-230, p<0.006) or in SN patients (GHRP-6: GHp: 39.1+/-3.1, p<0.0001; AUC: 2792+/-158, p<0.0001; nAUC: 2705+/-165, p<0.00005. GHRH+PD: GHp: 27.5+/-3.7, p<0.0001; AUC: 1873+/-251, p<0.0001; nAUC: 1692+/-219, p<0.0005). Unlike control groups, in PWS patients GH levels after GHRP-6 did not differ from those obtained after GHRH+PD. Interestingly, low IGF-I values were present in all PWS subjects. Furthermore, no patient with PWS showed normal GH response to the previously performed GH stimulation tests. As already reported, GH release after GHRP-6 or GHRH+PD was significantly lower in OB than in SN subjects. In conclusion, our data indicate that: 1) GH response to GHRP-6 is clearly impaired in PWS; 2) the blunted GH responses to the provocative stimuli in PWS are not an artifact of obesity; 3) short stature in PWS is caused by a complex dysfunction of the hypothalamo-pituitary structures.     

Acute ghrelin response to intravenous dexamethasone administration in idiopathic short stature or isolated idiopathic growth hormone-deficient children

Acylated ghrelin has been originally described for its potent GH-releasing activity mediated by the activation of the GH secretagogue receptor type 1a. More recently, ghrelin has been reported to exert several other GH-independent biological actions, among which in the modulation of metabolic functions. Glucocorticoids are well known to exert important metabolic functions but also to modulate GH secretion, although through mechanisms that have not been fully clarified so far. Interestingly, the existence of a feedback link between glucocorticoids and ghrelin system has already been reported. The aim of our study was to evaluate the acute GH and ghrelin responses to dexamethasone (DEX) administration in children with idiopathic short stature (ISS) or isolated idiopathic GH deficiency (GHD). Eight children with ISS (age: 9.5+/-1.2 yr) and 7 with GHD (12.1+/-1.4 yr) underwent iv DEX administration (0.3 mg/body surface area at 0 min). IGF-I, GH, and ghrelin levels were assayed at baseline and every 30 min from 120 up to 240 min after DEX. Compared to baseline levels DEX decreased ghrelin in ISS at 120 min and 240 min (p<0.04). On the other hand DEX did not modify ghrelin levels in GHD. After DEX, ghrelin was reduced in ISS compared to GHD (p<0.02). DEX increased GH in ISS but not in GHD (peak: 11.1+/-1.2 vs 7.6+/-0.9 microg/l). Basal, as well as after-DEX ghrelin levels negatively correlated with IGF-I in GHD (p<0.03) and with height SD score (HSDS) in ISS (p<0.02). Acute DEX administration is able to decrease ghrelin in ISS, but not in GHD children. Both basal and after-DEX ghrelin levels negatively correlate with IGF-I and HSDS. All these data suggest the existence of a feedback link among ghrelin, glucocorticoids and the GH/IGF-I axis.     

Long-term monitoring of rec-GH treatment by serial determination of serum aminoterminal propeptide of type III procollagen in children and adults with GH deficiency

Serum aminoterminal propeptide of type III procollagen (PIIINP) levels, a reliable marker of collagen formation, were evaluated in children (C=7) and adults with childhood-onset (CO=10) and acquired (A=18) GH deficiency (GHD) before, during and after withdrawal of rec-GH therapy (C=0.6 IU/kg/week, CO=0.5 IU/kg/week, A=0.25 IU/kg/week). The duration of treatment was 12 months for C and A and 6 months for CO; investigations were carried out before and at 3, 6, 9 and 12 months (for C and A) and at 3 and 6 months (for CO) of GH treatment and 6 months after the withdrawal of therapy (for A and CO). Data obtained from patients were compared with those recorded in two age- and sex-matched control groups. Before treatment, serum PIIINP levels were significantly lower (p<0.001) in C with GHD (mean+/-SE: 2.9+/-0.4 ng/ml) than in controls (6.1+/-0.4 ng/ml), while no significant differences were recorded between adults with CO/A-GHD (3.7+/-0.5 ng/ml and 3.4+/-0.2 ng/ml) and controls (3.2+/-0.2 ng/ml). GH treatment caused a significant increase (p<0.0001) of PIIINP levels both in C (3rd month: 4.4+/-0.2 ng/ml, 6th month: 5.1+/-0.4 ng/ml, 12th month: 5.1+/-0.5 ng/ml), CO-GHD (3rd month: 12.7+/-1.2 ng/ml; 6th month: 10.2+/-0.6 ng/ml) and A-GHD (3rd month: 10.0+/-1.0 ng/ml; 6th month: 8.4+/-0.6 ng/ml; 12th month: 7.0+/-0.7 ng/ml), the increase being dose-dependent (more marked and sustained in adults with CO-GHD). The maximal stimulation of collagen synthesis occurred after 3 months of GH treatment in adults with GHD, while a more gradual and less relevant increase was observed in C with GHD. Six months after the withdrawal of GH therapy, serum PIIINP levels of adults with CO-GHD (3.6+/-0.3 ng/ml) were similar to those recorded before treatment, while in adults with A-GHD serum PIIINP levels (2.6+/-0.2 ng/ml) were significantly lower (p<0.01) than in basal condition. In conclusion, our study shows that: a) GHD is associated with a reduction of soft tissue formation in children, while it seems to exert no relevant effects in adults with GHD; b) GH therapy causes a rapid stimulation of collagen turnover, which shows a different pattern in children and adults; c) the GH-induced stimulation of collagen synthesis is rapidly removed after the withdrawal of GH treatment. For these reasons, the determination of peripheral markers of GH effects appears useful for the monitoring of GH therapy and can contribute to assess the "tailored" substitutive dose for the individual patient.     

血清胰岛素样生长因子及其结合蛋白诊断儿童生长激素缺乏症的价值

为了解血清胰岛素样生长因子1（IGF－1），胰岛素样生长因子结合蛋白－3（IGFBP－3）浓度与生长激素缺乏症（GHD）患儿生长激素（GH）激发试验中血清生长激素峰值的关系，以确定血清IGF－1，IGFBP－3浓度诊断GHD的价值，为其代替GH激发试验提供依据，选择GHD患儿62例（男39例，女23例）为GHD组，60例健康儿童（男38例，女22例）为对照组。分别用放射免疫分析（RIA）法，免疫放射分析（IRMA）法检测GHD组血清IGF－1，IGFBP－3浓度，同时被GH激发试验，测定血清GH峰值，并比较其与IGF－1，IGFBP－3的关系，测定对照组血清IGF－1，IGFBP－3。结果显示，GHD组血清IGF－1，IGFBP－3均显著低于对照组（t分别为3.116,11.579,p均＜0．01）；GHD组血清IGF－1，IGFBP－3浓度与GH激发试验中的GH峰值呈显著正相关（r分别为。331，0。347，P均＜0．01）；GHD组血清IGF－1，IGFBP－3降低的阳笥率分别为97．58％，98．38％，与激发试验的阳性率（100％），比较无统计学意义（x^2分别为.3074,2.033,P均＞0．05）。表明血清中IGF－1，IGFBP－3浓度检测对诊断GHD有重要价值，认为检测血清中IGF－1，IGFBP－3浓度可以替代GH激发试验。     

Leptin concentrations in GH deficiency: the effect of GH insensitivity

Disorders of GH secretion are known to impair the physiological lipostat and to affect the secretion of leptin, a sensitive marker of regional fat accumulation and total body composition. In both children and adults with GH deficiency (GHD), leptin levels are increased proportionately with enhanced adiposity. In GHI, mutations of the GH receptor gene result in a phenotype similar to GHD, with increased adiposity and unfavorable lipid profiles. To examine the impact of different forms of growth disorders on leptin production, we measured leptin levels in 22 GHI patients homozygous for the E180 splice mutation (15 females and 7 males, aged 8-37 yr) and compared results with those obtained in 20 subjects heterozygous for the mutation (11 females and 9 males, aged 7-54), 17 idiopathic GHD patients (6 females and 11 males, aged 3-34), and 44 normal subjects (25 females and 19 males, aged 7-45). After the baseline evaluation, all subjects received two 7-d GH treatments at doses of 0.025 and 0.050 mg/kg x d in random order. Leptin, IGF-I, and IGF-binding protein-3 (IGFBP-3) were assayed by specific immunoassays. IGF-I and IGFBP-3 levels were significantly lower (P < 0.0001) in homozygous GHI and GHD patients compared with either controls or GHI heterozygotes. Circulating leptin levels were significantly higher in homozygous GHI patients than in normal controls (20.7 +/- 4.2 vs. 8.7 +/- 1.4 microg/liter) as well as when compared with heterozygous GHI subjects (14.4 +/- 3.4 microg/liter) and GHD patients (9.8 +/- 1.6 microg/liter; P < 0.01). Similar results were obtained when leptin was normalized for body mass index. When subjects were subgrouped by gender, leptin levels were significantly higher (P < 0.05) in GHI females than in females of all other groups and were significantly increased in GHD males (P < 0.01 vs. control males). Within the study groups, females had significantly higher leptin levels than males in controls (12.7 +/- 2 vs. 3.3 +/- 1 microg/liter; P < 0.001) and homozygous GHI patients (28.7 +/- 5.3 vs. 6.9 +/- 2.3 microg/liter; P < 0.05), but not in heterozygous GHI (20.1 +/- 5.4 vs. 7.3 +/- 2.4 microg/liter; P < 0.06) and GHD (10.9 +/- 2.6 vs. 9.2 +/- 2.1 microg/liter) patients. By multivariate analysis, log-normalized leptin levels were best predicted by gender and body mass index in homozygous GHI patients as well as in normal subjects. During the 1-wk courses of GH therapy, serum IGF-I and IGFBP-3 levels significantly increased (P < 0.0001) in GHD patients, heterozygous GHI patients, and control subjects at both GH doses. Inversely, leptin levels did not change significantly during either course of GH administration in the groups examined. These data demonstrate that leptin is increased in patients affected with long-standing homozygous GHI, probably reflecting abnormalities of body composition and metabolism typical of this condition.     

Glucagon stimulation test for the diagnosis of GH deficiency in adults

The insulin tolerance test (ITT) is considered the test of choice for the diagnosis of GH deficiency (GHD). However, in patients with contraindications to ITT, alternative provocative tests must be used with appropriate cut-offs. The glucagon stimulation test has proved to be a safe, low-cost and effective means of stimulating GH secretion, and therefore can be considered as a suitable alternative to the ITT. We have studied the GH response to the glucagon test in 33 patients with known pituitary disease, 12 males and 21 females, aged between 21 and 60 yr (41.18 +/- 9.47 yr); 5 had isolated GHD and 28 had panhypopituitarism. We also evaluated a control group of 25 individuals, matched for age and sex (8 males and 17 females), aged between 20 and 60 yr (39.28 +/- 12.10 yr). They were selected via the ITT if their peak GH response was > 5.0 ng/ml. GH peak after glucagon was significantly lower in the group of patients compared to the control group (0.49 +/- 0.85 vs 8.69 +/- 5.85 ng/ml, p = 0.0001). Receiver-operating characteristic (ROC) plot analyses of the control and GHD group showed an area under the curve of 0.982 for GH peak response to glucagon. The response value of 3.0 ng/ml showed the best pair of sensitivity (97%)/specificity (88%), and was chosen as the cut-off defining GHD. After evaluation of positive predictive values (PPV) and negative predictive values (NPV) through simulation of different prevalences of the disease, we concluded that the cut-off point of 3.00 ng/ml maximizes both PPV and NPV (100%). In conclusion, we have shown that the glucagon stimulation test has a good performance and great diagnostic accuracy for the diagnosis of GHD.     

Monitoring serum insulin-like growth factor-I (IGF-I), IGF binding protein-3 (IGFBP-3), IGF-I/IGFBP-3 molar ratio and leptin during growth hormone treatment for disordered growth

OBJECTIVE: Serum IGF-I levels are monitored during GH replacement treatment in adults with GH deficiency (GHD) to guide GH dose adjustment and to minimize occurrence of GH-related side-effects. This is not routine practice in children treated with GH. The aim of this study was to evaluate changes in (1) serum IGF-I, IGFBP-3 and IGF-I/IGFBP-3 molar ratio, and (2) serum leptin, an indirect marker of GH response, during the first year of GH treatment in children with disordered growth. DESIGN: An observational prospective longitudinal study with serial measurements at five time points during the first year of GH treatment was carried out. Each patient served as his/her own control. PATIENTS: The study included 31 patients, grouped as (1) GHD (n = 20) and (2) non-GHD (Turner syndrome n = 7; Noonan syndrome n = 4), who had not previously received GH treatment. MEASUREMENTS: Serum IGF-I, IGFBP-3 and leptin levels were measured before treatment and after 6 weeks, 3 months, 6 months and 12 months of GH treatment, with a mean dose of 0.5 IU/kg/wk in GHD and 0.7 IU/kg/wk in non-GHD groups. IGF-I, IGFBP-3 and the calculated IGF-I/IGFBP-3 molar ratio were expressed as SD scores using reference values from the local population. RESULTS: In the GHD group, IGF-I SDS before treatment was lower compared with the non-GHD (-5.4+/-2.5 vs. -1.8+/-1.0; P<0.001). IGF-I (-1.8 SDS +/- 2.2) and IGFBP-3 (-1.1 SDS +/- 0.6) levels and their molar ratios were highest at 6 weeks and remained relatively constant thereafter. In the non-GHD group, IGF-I levels increased throughout the year and were maximum at 12 months (0.3 SDS +/- 1.4) while IGFBP-3 (1.1 SDS +/- 0.9) and IGF-I/IGFBP-3 molar ratio peaked at 6 months. In both groups, IGF-I SDS and IGF-I/IGFBP-3 during treatment correlated with the dose of GH expressed as IU/m2/week (r-values 0. 77 to 0.89; P = 0.005) but not as IU/kg/week. Serum leptin levels decreased significantly during GH treatment in the GHD (median before treatment 4.0 microg/l; median after 12 months treatment 2.4 microg/l; P = 0.02) but not the non-GHD (median before treatment 3.0 microg/l; median after 12 months treatment 2.6 microg/l). In the GHD group, serum leptin before treatment correlated with 12 month change in height SDS (r = 0.70, P = 0.02). CONCLUSIONS: The pattern of IGF-I, IGFBP-3 and their molar ratio during the first year of GH treatment differed between the GHD and non-GHD groups. Calculation of GH dose by surface area may be preferable to calculating by body weight. As a GH dose-dependent increase in serum IGF-I and IGF-I/IGFBP-3 may be associated with adverse effects, serum IGF-I and IGFBP-3 should be monitored routinely during long-term GH treatment. Serum leptin was the only variable that correlated with first year growth response in GHD.     

Growth hormone isoforms release in response to physiological and pharmacological stimuli

Ten healthy subjects used to performing regular physical activity and eight subjects affected by idiopathic isolated GH deficiency (GHD) were enrolled; 22- and 20-kDa GH secretion and its biological activity were evaluated in response to pharmacological stimuli such as arginine, L-dopa or glucagon in GHD children, while the hormonal response to exercise was studied according to Bruce protocol in healthy subjects. We found a significant increase in 22- and 20-kDa GH level in healthy subjects after monitored physical exercise (MPE; basal 0.28+/-0.12 vs 7.37+/-2.08 ng/ml and basal 0.076+/-0.04 vs 0.18+/-0.05 ng/ml, respectively). Furthermore, the 22-kDa/20-kDa ratio significantly increased in children who had undergone MPE and the GH bioactivity basal mean value also increased significantly after exercise (basal 2.86+/-0.76 vs 7.64+/-1.9 ng/ml). The mean value of 22-kDa GH in GHD patients increased significantly following GH pharmacological stimulation (2.78+/-0.63 ng/ml) when compared with mean basal (0.20+/-0.11 ng/ml) value. In the GHD group the basal concentration of 20-kDa GH significantly increased following GH pharmacological stimulation (0.34+/-0.11 vs 0.72+/-0.2 ng/ml); the 22-kDa/20-kDa ratio significantly increased too. Likewise, GH bioactivity in children with GHD increased significantly after pharmacological stimulation test (basal 2.53+/-0.56 vs 7.33+/-1.26 ng/ml). Both GH isoform concentrations and their biological activity are significantly increased in healthy subjects after submaximal exercise protocol and in GHD children after pharmacological stimuli.     

Characteristics of adult patients with growth hormone deficiency who underwent neurosurgery for functioning and non-functioning pituitary adenomas and craniopharyngiomas

The aim of the present study was to evaluate the characteristics of GH deficiency (GHD) in adult patients after neurosurgery for pituitary adenomas and craniopharingiomas. One hundred and one GHD patients, (42 F/59 M), aged 47.58+/-14.4 yr (mean+/-SD; range 21-78), body mass index (BMI) 28.6+/-0.6, with a history of adult-onset hypothalamic-pituitary disease, were recruited for the study. The whole group included: 45 non-functioning pituitary adenomas, 23 craniopharyngiomas, 16 PRLomas, 8 GHomas, 7 ACTHomas and 2 FSHomas; in particular 51 were macroadenomas and 27 microadenomas. At study entry, GHD diagnosis was carried out by assessing GH secretion after GHRH+arginine. All patients were submitted to the study at least 12 months after neurosurgery and, where needed, subjects were replaced with an appropriate treatment. GHD was mild in 3/101 (3%) and severe in 98/101 patients (97%). Other hormone deficiencies associated with GHD were considered: TSH, ACTH, FSH/LH, ADH. The distribution of peak GH among all patients, according to the type of disease before neurosurgery, showed that patients with Cushing disease were characterized by the presence of higher peak GH. According to the number of additional hormone deficits, the distribution of peak GH among all patients was as follows: GHD was isolated in 4/101 subjects (4%; group A), while it was associated with 1 (14/101, 14%; group B), 2 (22/101, 22%; group C), 3 (44/101, 43%; group D) and 4 hormone deficits (17/101, 16%; group E). GHD was severe in all patients in the panhypopituitaric group. Total IGF-I plasma levels in the whole group of GHD patients were 95.2+/-4.2 microg/l. In all groups of patients IGF-I was lower in subjects with severe GHD than in those with mild GHD (93.6+/-4.1 vs 148.6+/-33.6 microg/l, p<0.03). In particular, according to the type of disease presented before neurosurgery, patients with Cushing disease were characterized by the presence of higher IGF-I plasma levels compared to the other. According to the number of additional deficits, the distribution of IGF-I plasma levels was characterized by higher values when GHD was isolated than when it was associated with multiple hormone deficiencies. IGF-I plasma levels were positively associated to peak GH during GHRH+arginine (r=0.4, p<0.0005). We conclude that patients after neurosurgery approach for sellar and parasellar neoplasia, within an appropriate clinical context, and both the presence of additional pituitary hormone deficiency and low levels of IGF-I can be considered a clear GHD condition, and therefore do not require provocative tests evaluating GH secretion.     

Reassessment of growth hormone status is required at final height in children treated with growth hormone replacement after radiation therapy

The most appropriate way to manage GH replacement in the transition period to adulthood in children treated with GH for GH deficiency (GHD) is controversial. The Growth Hormone Research Society suggests that the retesting of GH status at final height (FH) is unnecessary in the presence of severe organic GHD, and cranial irradiation falls into this etiological category. This recommendation has never been validated. To investigate whether patients diagnosed in childhood as GHD secondary to irradiation require retesting after FH, GH status has been reassessed in a large cohort of irradiated children treated with GH during childhood. Seventy-three children underwent biochemical assessment of GH status after irradiation and again at FH after GH therapy had been discontinued; 66 and 67 of the 73 patients underwent two provocative tests at the two time points, respectively. The characteristics of the cohort include a median age at irradiation of 5 yr (range, 1-11 yr), a median biological effective dose (BED) of irradiation to the hypothalamic pituitary axis of 54 Gy (range, 23-82 Gy), and a median time of GH status reassessment after FH of 0.4 yr (range, 0-8.4 yr). During childhood, patients with all degrees of GHD (peak GH responses to provocative test < 6.7 ng/ml) are treated, whereas in adulthood, only patients with severe GHD (peak GH responses to provocative test < 3 ng/ml) are considered for GH replacement. GH status has been grouped as follows: group 1, peak GH less than 3 ng/ml to both tests (severe GHD); group 2, one test with a peak GH less than 3 ng/ml and the other test with a peak of 3 ng/ml or greater; group 3, peak GH of 3-6.7 ng/ml to both tests; group 4, one test with a peak GH of 3-6.7 ng/ml and the other test with a peak of more than 6.7 ng/ml; and group 5, peak GH more than 6.7 ng/ml to both tests (normal GH status). In childhood, the number of patients in groups 1, 2, 3, and 4 were 33, 22, 17, and one, respectively. At retesting, severe GHD was diagnosed in 21 (64%) of 33 patients who were diagnosed in childhood with severe GHD (group 1) and 17 (44%) of 39 patients who were diagnosed in childhood with moderate GHD (groups 2 and 3). In total, 35 (48%) of 73 patients in the whole cohort and 12 (36%) of 33 patients with severe GHD in childhood did not fulfill the severe GHD biochemical criteria for GH replacement in adulthood. Using multiple linear regression, GH status at retesting is predicted by BED, age at irradiation, and use of chemotherapy. In conclusion, the diagnosis of severe GHD in childhood secondary to irradiation should not be taken as irrefutable evidence of permanent severe organic GHD, and our recommendation is that retesting of GH status at FH should be mandatory.     

Body composition,IGF-I and IGFBP-3 concentrations as outcome measures in severely GH-deficient (GHD) patients after childhood GH treatment: a comparison with adult onset GHD patients

If GH therapy of children with GH deficiency (GHD) has been adequate, body composition should be comparable to that of patients who have undergone normal childhood development and become hypopituitary thereafter. To assess this, body composition was determined in 92 patients with childhood onset (CO) GHD, aged 18-30 yr, who had been treated to final height with GH for 8.98 +/- 4.30 yr and had stopped treatment 1.57 +/- 1.20 yr previously, but who remained GHD (assessed by a GH stimulation test and IGF-I values). These were compared with 35 age-matched GH-na?ve hypopituitary patients with adult onset (AO) GHD. Lean body mass, fat mass, and total bone mineral content were assessed by dual energy x-ray absorptiometry and corrected for actual height. CO patients were shorter (CO height, -1.18 +/- 1.16 SD score; AO height, -0.38 +/- 1.12 SD score; P < 0.001) and had lower body mass index (CO, 23.19 +/- 5.76 kg/m(2); AO, 28.9 +/- 6.27 kg/m(2); P < 0.001) than the AO group. Although there were gender differences, within genders CO patients had lower lean body mass, fat mass, and bone mineral content (P < 0.001 in all cases) compared with AO patients. Standard deviation scores for IGF-I (CO female, -9.2 +/- 3.1; AO female, -5.2 +/- 2.6; CO male, -6.4 +/- 2.7; AO male, -3.5 +/- 2.3; P < 0.001 within each gender) and IGFBP-3 (CO female, -3.5 +/- 2.5; AO female, -1.7 +/- 1.5; CO male, -2.8 +/- 2.0; AO male, -1.1 +/- 1.6; P < 0.001 within each gender) were significantly lower in the CO group. These results suggest that patients with CO GHD who were treated to final height suffer a significant maturational deficit despite GH replacement during childhood.     

Relationship between the morphological evaluation of the pituitary and the growth hormone (GH) response to GH-releasing hormone Plus arginine in children and adults with congenital hypopituitarism

The relationship between the hypothalamus-pituitary morphology and the somatotroph responsiveness to maximal provocative tests exploring the GH releasable pool is still unclear. We evaluated the GH-releasing effect of GHRH plus arginine (GHRH plus Arg) in 36 patients with congenital GH deficiency (GHD) according to their pituitary magnetic resonance imaging findings, consisting of anterior pituitary hypoplasia, stalk agenesis (neural and or vascular component), and posterior pituitary ectopia. Seventeen children (12 boys and 5 girls, aged 1--5.2 yr) were evaluated at the time of diagnosis of GHD (mean age, 3.6 +/- 1.4 yr), and 19 adults (13 males and 6 females, aged 15.9-28.6 yr) with childhood-onset GHD were reevaluated after completion of GH treatment (at least 6 months of withdrawal) at a mean age of 20.5 +/- 3.5 yr. Eleven children had isolated GHD, and 6 had multiple pituitary hormone deficiency (MPHD) whereas 7 adults had isolated GHD, and 12 had MPHD. A residual vascular component of the pituitary stalk was visualized in 7 children and 7 adults with isolated GHD, whereas magnetic resonance imaging showed complete pituitary stalk agenesis (both vascular and neural components) in 10 children and 10 adults, including 16 with MPHD (6 children) and 4 children with isolated GHD. In the children, the median peak GH response to GHRH plus Arg (7.6 microg/L; range, 2.4--40.2 microg/L) was significantly higher than that in the adults (1.8 microg/L; range, 0.8--37.4 microg/L; P = 0.0039); it was also significantly higher in the isolated GHD patients (18 microg/L; range, 3.3--40.2 microg/L) than in those with MPHD (1.9 microg/L; range, 0.8--7.6 microg/L; P = 0.00004). In the patients with residual vascular component of the pituitary stalk the median peak GH responses to GHRH plus Arg (19.1 microg/L; range, 1.6--40.2 microg/L) was significantly higher than that in patients with complete pituitary stalk agenesis (2.2 microg/L; range, 0.8--8.8 microg/L; P = 0.00005). There was a trend toward a decrease with age in peak GH response to GHRH plus ARG: Mean serum insulin-like growth factor I (IGF-I) levels were 36 +/- 7.1 microg/L in the children and 63.5 +/- 22.6 microg/L in the adults (P = 0.0001). The mean IGF-I level did not differ between the children with (35.7 +/- 4.8 microg/L) and those without (36.3 +/- 8.7 microg/L) the pituitary stalk; it was much higher in the adults with residual vascular pituitary stalk (81.1 +/- 17.7 microg/L) than in those with complete pituitary stalk agenesis (47.7 +/- 12.5 microg/L; P = 0.0002). The IGF-I level was 36.1 +/- 6.7 microg/L in the isolated GHD children and 36 +/- 8.6 microg/L in those with MPHD; levels were 82.1 +/- 19.4 and 52.7 +/- 16.8 microg/L respectively, in the adults (P = 0.003). In this study we have confirmed that the partial integrity of the hypothalamic pituitary connections is essential for GHRH plus Arg to express its GH-releasing activity and have shown that this provocative test is able to stimulate GH secretion to a greater extent in those patients with GHD, but with a residual vascular component of the pituitary stalk. This test is reliable in the diagnosis of congenital hypopituitarism in both children and adults when associated with complete pituitary stalk agenesis and MPHD. In younger children with congenital GHD but less severe impairment of the pituitary stalk the GH response to GHRH plus Arg may be within the normal range; deterioration of pituitary GH reserve with a GH response of less than 10 microg/L after 20 yr of age makes this test very sensitive in the diagnosis of adult GHD.     

Chronic treatment with inhaled corticosteroids does not modify leptin serum levels.

AIM: To assess the influence of a short-term treatment with low-dose inhaled corticosteroids on leptin serum levels. PATIENTS: 14 prepubertal children, mean age 5.1 +/- 2.4 years, treated with inhaled fluticasone propionate 100 microg b.d. and 16 prepubertal children, mean age 8.3 +/- 1.3 years, treated with inhaled budesonide 200 microg b.d. METHODS: All children underwent a CRH test with evaluation of leptin, cortisol and ACTH levels before and after 3 months of treatment. RESULTS: Fluticasone group: no difference was found between basal cortisol level, delta and area under the curve (AUC) before and after treatment, though cortisol peak was significantly lower following treatment. Basal ACTH level, peak and AUC were significantly lower after treatment. Budesonide group: no statistically significant difference in any of the parameters regarding cortisol and ACTH secretion was observed before and after treatment. No significant changes in basal serum leptin levels and AUC were observed following treatment in both groups. Furthermore no significant variation in leptin level was observed during both CRH tests. DISCUSSION: Leptin secretion does not seem to be affected by low-dose inhaled corticosteroids; moreover leptin does not seem to be involved in the response of the HPA axis to stress.     

Metabolic parameters and adipokine profile during GH replacement therapy in children with GH deficiency

OBJECTIVE: GH replacement therapy in children with GH deficiency (GHD) mainly promotes linear growth. Not only have very few studies fully analyzed the metabolic consequences of GH therapy, but also the question as to whether GH may affect adipokine secretion has been insufficiently investigated. Our aim was to study the effects of GH replacement therapy on auxological data, lipid and glycemic profiles, insulin homeostasis (HOMA-IR) and serum adipokines in children. METHODS: This was a 1-year prospective study. Thirty-four GHD children (11.6 +/- 2.6 years) and thirty healthy matched controls were enrolled. Children affected by GHD were studied both before beginning continuous GH replacement therapy and again at 12 months. RESULTS: At the beginning of the study, total and LDL cholesterol were higher in GHD children than in controls (P<0.001), whereas HDL cholesterol, triglycerides, insulin, HOMA-IR, leptin, and adiponectin were similar. At 12 months of continuous GH replacement therapy in the GHD group, there was a significant increase in both auxological data and IGF-I (P<0.001); total cholesterol (P<0.001), LDL (P<0.001), triglycerides (P<0.005), and leptin (P<0.001) decreased significantly; HDL (P<0.003), insulin (P<0.001), HOMA-IR (P<0.001) increased while adiponectin was unmodified. Furthermore, IGF-IDelta showed an inverse correlation with leptin Delta (rho = -0.398, P = 0.02). CONCLUSIONS: In GHD children, the evaluation of metabolic parameters proves to be a useful tool for the evaluation of auxological parameters during GH replacement therapy. In our study, GH replacement therapy in GHD children improved final height, restored IGF-I levels, reduced leptin levels, and improved the lipid profile, without producing any unfavorable effects on glucose metabolism.