A new test for the diagnosis of growth hormone deficiency due to primary pituitary impairment: combined administration of pyridostigmine and growth hormone-releasing hormone

Growth Hormone Perturbations in Fibromyalgia: A Review

OBJECTIVE

Fibromyalgia (FM) is a syndrome characterized by chronic widespread pain, fatigue, disrupted sleep, depression, and physical deconditioning. In this article, we review the literature on the normal activity of the hypothalamic-pituitary-growth hormone-insulin-like growth factor-1 (HP-GH-IGF-1) axis and its perturbations in FM subjects.

METHODS

Studies included in this review were accessed through an English language search of Cochrane Collaboration Reviews. Keyword MeSH terms included "fibromyalgia," "growth hormone" (GH), or "insulin-like growth factor-1" (IGF-1).

RESULTS

Twenty-six studies enrolling 2006 subjects were reviewed. Overall, low levels of IGF-1 were found in a subgroup of subjects. Growth hormone stimulation tests often revealed a suboptimal response, which did not always correlate with IGF-1 levels. No consistent defects in pituitary function were found. Of the 3 randomized placebo controlled studies, only 9 months of daily injectable recombinant GH reduced FM symptoms and normalized IGF-1.

CONCLUSIONS

These studies suggest that pituitary function is normal in FM and that reported changes in the HP-GH-IGF-1 axis are most likely hypothalamic in origin. The therapeutic efficacy of supplemental GH therapy in FM requires further study before any solid recommendations can be made.

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.

Abnormalities of GH secretion in a young girl with Floating-Harbor syndrome

We present a 9.1-year-old girl of Calabrian (Italy) ancestry, with clinical features (cranio-facial dysmorphism, short stature with delayed bone age and speech delay) suggesting the diagnosis of Floating-Harbor syndrome (FHS). Physical examination showed: height 113.9 cm (-2.9 SD), with a parent's target of 156.2 cm (+1.0 SD), weight 20.7 kg, BMI 16.0 (-0.04 SD), and many phenotypic abnormalities: long eyelashes, large bulbous nose with broad nasal bridge, short philtrum, moderately broad mouth, tooth folding and malocclusion, posteriorly rotated ears, low posterior hair line, short neck, clinodactyly of the 5th finger and hyperextensible finger joints. Diffused hyperpigmentation and hypertrichosis with sporadic pubic terminal hairs, but neither clitoromegaly nor other signs of hyperandrogenism and/or precocious puberty, were observed (T1, P1). Carpal bone evaluation showed a delayed bone age (TW2: 5-5/10, - 3.6 yr) and the statural age/bone age ratio was 1.1. Other dysmorphic syndromes were excluded on the basis of clinical evidence, also evaluated by a computer-assisted search (P.O.S.S.U.M. version 3.5, 1992). Analysis of chromosome 22 by the FISH method, using specific probes Cos29 and Tuple1, excluded microdeletions in the region 22q11.2, typical of Velo-cardio-facial syndrome. In this case, we report the impairment of serum GH responsiveness (GH baseline values: 0.2-1.9 ng/ml) to the administration of oral 150 microg clonidine [peak 4.7 ng/ml, normal values (nv)>10 ng/ml] and oral 4 mg dexamethasone (8.1 ng/ml, nv>10 ng/ml). Moreover, the evaluation of spontaneous 24-h GH secretion (Carmeda AB, Stockholm, Sweden) showed low mean GH levels (1.75 ng/ml, nv>3.0 ng/ml), with a maximum sleep-related peak of 2.8 ng/ml. Serum IGF-1 values were in the low-normal range (80-176 ng/ml, nv 133-626 ng/ml). While in FHS the cranio-facial features minimize with advancement of age, the impairment of growth velocity is permanent and results in severe dwarfism. In our case, treatment with recombinant GH (0.10 U/kg/day), administered by a needle-free device, induced a dramatic increase of growth velocity, increasing the height from -2.8 to -1.9 SD after 18 months, thus indirectly confirming a role of GH deficiency in the pathogenesis of FHS dwarfism.

Insulin-like growth factor-I restores the reduced somatostatinergic tone controlling growth hormone secretion in cirrhotic rats

BACKGROUND/AIMS

An altered growth hormone/insulin-like growth factor-I (GH/IGF-I) axis occurs in advanced liver cirrhosis, characterised by diminished serum levels of IGF-I and increased concentrations of GH. Under normal conditions, GH release is mediated by somatostatin (SS) inhibition. However, the influence of SS on GH release in cirrhosis is not well known. IGF-I supplementation has beneficial effects in experimental cirrhosis, and - under physiological conditions - IGF-I increases SS, inhibiting GH. The aims of this work were to study SS tone in cirrhotic animals and to evaluate whether IGF-I treatment influences SS tone, controlling GH secretion in cirrhosis.

METHODS

We studied the influence of SS on GH secretion by assessing GH response to pyridostigmine (PD) in cirrhotic rats treated and untreated with IGF-I. Liver cirrhosis was induced with CCl4-inhalation for 11 weeks in male Wistar rats. The animals were randomly divided into two groups: CI+IGF (n=12), which received IGF-I treatment for 12 days (2 microg/100 g body wt-1 x d-1) and CI (n=12), which received saline. Healthy controls (CO, n=12) were studied at the same time. On day 13, animals from each group were subdivided into two groups (n=6) in order to explore the effect of a PD intrajugular bolus (10 microg x 100 gbw-1) on serum GH levels (at 0,10,20,30 and 60 min), which were assessed by RIA.

RESULTS

PD bolus did not exert any effect on GH serum levels in the CI group, suggesting a low SS tone in cirrhotic rats. However, PD induced an increase in GH levels into CO and CI+IGF groups. In conclusion, as occurs under normal conditions, the cholinergic system is a significant modulator of GH secretion in experimental liver cirrhosis.

CONCLUSION

Cirrhotic rats have a reduced somatostatinergic tone which can be restored by IGF-I supplementation, suggesting that somatostatin is the main factor involved in the feed-back regulation between GH and IGF-I in cirrhosis.

Short procedure of GHRH plus arginine test in clinical practice

Either in children or in adults, arginine (ARG) alone and combined with GHRH (GHRH+ARG) are reliable tests for the diagnosis of GH deficiency. The procedures of these tests generally include GH measurement every 15 min from baseline up to 90-120 min. Aim of our study was to verify if the procedure of these tests could be usefully shortened in clinical practice. To this goal we have studied 173 normally growing children and adolescents (C, 117 M and 56 F, age: 11.3 +/- 0.4 yr.) and 125 young and middle aged normal adults (A, 68 M and 57 F, age: 30.0 +/- 0.6 yr.). ARG alone test was performed by 81 C and 33 A (0.5 g/kg arginine, i.v., from 0 to +30 min, up to a maximum of 30 g) while GHRH (1 microg/kg i.v. bolus at 0 min) + ARG test was performed by 92 C and 92 A. After ARG alone, taking into account data from +15 to +105 min, GH values above the 3rd centile limit of arbitrary cut-off (7 or 10 microg/l in C and 5 microg/l in A) occurred in 85% or 64% and 94% subjects, respectively. After GHRH+ARG test, taking into account only data at +30, +45, +60 min GH values above the 3rd centile limit (20 microg/l in C and 16.5 microg/l in A) occurred in 99% of subjects in both groups. Taking into account only these 3 timing points, the percentage of GH peak above the third centile limits after ARG alone was never higher than 60% in C and 85% in A. In conclusion, this study shows that single GHRH+arginine test can be reliably performed in a shortened procedure which makes easier the clinical practice and further reduces costs.

Reduction of the pituitary GH releasable pool in short children with GH neurosecretory dysfunction

OBJECTIVES

The classical 'GH neurosecretory dysfunction' (GHNSD) refers to slowly growing children with normal GH responses to classical provocative tests but impaired spontaneous GH secretion over 24 h frequently leading to low IGF-I levels. Thus it has been assumed that these subjects have insufficiency of spontaneous GH secretion due to neuroendocrine abnormalities in spite of a normal releasable pool of GH. However, classical provocative tests do not reliably assess the maximal somatotroph capacity; thus it is still unclear if the GH pool is really preserved or not. GHRH + arginine test is more potent than the classical tests and evaluates the maximal secretory capacity of somatotroph cells. The GH response to this stimulus is reproducible and also independent of age and puberty.

DESIGN AND PATIENTS

We studied the GH response to GHRH (1 microgram/kg iv) + arginine (ARG, 0.5 g/kg iv) in 19 short children with GHNSD (14 boys and 5 girls, age: 12.1 +/- 0.7 years, pubertal stages I-III, HV-SDS between -1.6 and -4.9; GH peak > 10 micrograms/l after classical stimuli but mean GH concentration (mGHc) < 3 micrograms/l). The results in GHNSD were compared with those in 38 short children with idiopathic or organic severe GHD (GHD, 29 boys and 9 girls, age: 11.2 +/- 0.6 years, pubertal stages I-III, HV-SDS between -1.8 and -4.4; GH peak < 10 micrograms/l after 2 classical provocative tests) and in 83 children with normal or familial short stature (NC, 59 boys and 24 girls, age: 11.5 +/- 0.3 years., pubertal stages I-III; HV-SDS > 25th centile, normal IGF-I levels).

RESULTS

Mean IGF-I levels in GHNSD (121.9 +/- 20.3 micrograms/l) were lower (P < 0.001) than those in NC (270.3 +/- 13.8 micrograms/l) but higher (P < 0.001) than those in GHD (72.0 +/- 4.0 micrograms/l). The mean GH concentration (mGHc) in GHNSD (2.1 +/- 0.1 micrograms/l) was lower (P < 0.01) than that in NC (4.9 +/- 0.5 micrograms/l) but higher (P < 0.01) than that in GHD (1.5 +/- 0.2 micrograms/l). On the other hand, the mean peak GH response to GHRH + ARG in GHNSD (43.7 +/- 3.7 micrograms/l) was markedly higher (P < 0.001) than that in GHD (8.2 +/- 0.9 micrograms/l) but significantly lower (P < 0.01) than that in NC (60. 4 +/- 2.7 micrograms/l). All GHD patients had peak GH responses to GHRH + ARG below the 3rd centile limit of normality (20 micrograms/l), while all GHNSD patients had peak GH responses within the normal range. No significant correlation was found between GH peak after GHRH + ARG, mGHc and IGF-I levels in each group.

CONCLUSION

Our study demonstrates that short children with 'GH neurosecretory dysfunction' show reduction in the GH releasable pool evaluated by the provocative and potent GHRH + arginine test. However, the peak GH response to a single GHRH + arginine test in GH neurosecretory dysfunction is always within the normal range indicating that this test as well as classical stimuli does not distinguish normal subjects from GH neurosecretory dysfunction.

Sequential administration of arginine and arginine plus GHRH to test somatotroph function in short children

The hormonal diagnosis of GH deficiency in childhood is conventionally based on the GH response to at least two provocative stimuli. Among these, arginine (ARG) has long been considered a classical, centrally mediated stimulus of GH secretion. ARG is also able to potentiate the GH response to GHRH, likely inhibiting hypothalamic somatostatin; this combined test is one of the most potent to explore the maximal secretory capacity of somatotroph cells. Based on these premises, we verified whether the sequential administration of ARG and ARG+GHRH could be feasible as single step provocative test to evaluate the GH releasable pool in short children. To this goal, 48 normal short children (35 M and 13 F, 12.0+/-0.4 yr, PS 1: 255 II-IV: 23) underwent a test with ARG (0.5 g/kg i.v. from 0 to +30 min) followed by a coadministration of ARG (from +120 to 150 min) plus GHRH (1 microg/kg i.v. at +120 min). ARG alone elicited a clear GH response (mean peak vs baseline: 12.1+/-1.7 vs 2.0+/-0.4 microg/l, p<0.001, Cmax range 12-51.0 microg/l). Following this GH rise, the hormonal levels at +120 min approached to baseline levels (4.2+/-0.8 microg/l) but then showed marked response to the coadministration of ARG+GHRH. The GH peak following ARG+GHRH (mean peak: 47.8+/-3.3 microg/l, p<0.001; Cmax 22.4-150.0 microg/l) was clearly higher (p<0.001) than that recorded after ARG alone. The GH responses to both ARG and ARG+GHRH were independent of gender, puberty, height velocity, body mass index (BMI) and IGF-I levels. Nine normal short children (16%) had GH peaks lower than 7 microg/l after ARG alone, while none showed GH peak below 20 microg/l after ARG+GHRH. Thus, ARG alone is a good stimulus of GH secretion but false positive responses frequently occur in normal short children. ARG+GHRH is a more potent stimulus giving no false positive responses even after previous challenge with ARG alone. Testing with sequential administration of ARG and ARG+GHRH may allow the single step evaluation of the somatotroph response to central and pituitary stimuli in short children.

Hexarelin-induced growth hormone response in short stature. Comparison with growth hormone-releasing hormone plus pyridostigmine and arginine plus estrogen

Hexarelin (HEX) is a synthetic hexapeptide with strong GH-stimulating activity. We evaluated GH response (expressed as maximum value after stimulus [Cmax] and as area under the curve [AUC]) to HEX at the doses of 1 microg/kg i.v. (HEX 1) and 2 microg/kg i.v. (HEX 2), in comparison with the responses to GHRH (1 microg/kg i.v.) + pyridostigmine (PD, 60 mg po) and to arginine (ARG, 0.5 mg/kg i.v.) + ethinylestradiol (EE, 1 mg/day po for 3 days before the stimulation), in 5 subjects with familial short stature (FSS), 11 with constitutional growth delay (CGD), 6 with GH neurosecretory dysfunction (NSD), and 5 with isolated growth hormone deficiency (GHD). Cmax and AUC after HEX 1 were 26.8+/-10.5 ng/ml and 1448+/-514 ng/min x ml in FSS, 23.6+/-14.4 ng/ml and 1146+/-750 ng/min x ml in CGD, 36.9+/-21.5 ng/ml and 2048+/-1288 ng/min x ml in NSD, 9.4+/-5.8 ng/ml and 498+/-200 ng/min x ml in GHD (Cmax and AUC in FSS and CGD, p<0.05 vs GHD). Cmax and AUC after HEX 2 were 37.7+/-16 ng/ml and 1979+/-888 ng/min x ml in FSS, 32.5+/-16.2 ng/ml and 1613+/-237 ng/min x ml in CGD, 39.7+/-20.7 ng/ml and 2366+/-1569 ng/min xml in NSD, 13.4+/-4.2 ng/ml and 645+/-293 ng/min x ml in GHD (Cmax in FSS, CGD and NSD p<0.01 vs GHD; AUC in NSD, p<05 vs GHD). Cmax and AUC after GHRH+/-PD were 46.6+/-8.8 ng/ml and 3294+/-1031 ng/min x ml in FSS, 25.9+/-11.2 ng/ml and 1464+/-735 ng/min x ml in CGD, 38.8+/-21.7 ng/ml and 2428+/-1399 ng/min x ml in NSD, 8.4+/-6.2 ng/ml and 685+/-572 ng/min x ml in GHD (Cmax and AUC in FSS, p<0.001 vs CGD and GHD; Cmax in CGD and NSD, p<0.001 vs GHD). Cmax and AUC after ARG+EE were 21.3+/-4.2 ng/ml and 1432+/-514 ng/min x ml in FSS, 14.8+/-10 ng/ml and 805+/-489 ng/min x ml in CGD, 22.2+/-12.8 ng/ml and 1199+/-309 ng/min x ml in NSD, 4.6+/-2.5 ng/ml and 247+/-191 ng/min x ml in GHD (Cmax and AUC in FSS, CGD and NSD, p<0.01 vs GHD). Specificity was 62% for HEX 1 and 75% for HEX 2, GHRH+PD and ARG+EE. From a diagnostic point of view, HEX 1 + HEX 2 was the association with the largest percentage of false positives (20% in FSS, 27% in CGD and 33% in NSD), HEX 1 +GHRH+PD resulted in 9% in CGD, while the combined use of HEX 1 or HEX 2 with GHRH+PD or ARG+EE and of GHRH+PD with ARG+EE did not show false positive responses.

IN CONCLUSION

I) the most effective dose of HEX was 2 microg/kg i.v.; 2) HEX did not show more specificity than GHRH+PD and ARG+EE; 3) the association of GHRH+PD with ARG+EE could yield the best results at lower costs, confirming these tests as first-line tools in evaluating GH secretion.

Hexarelin, a synthetic GH-releasing peptide, is a powerful stimulus of GH secretion in pubertal children and in adults but not in prepubertal children and in elderly subjects

GH-releasing peptides (GHRPs) and their non-peptidly mimetics are synthetic molecules which possess marked, dose-related and reproducible GH-releasing effect even after oral administration. Their potent stimulatory effect on GH secretion suggested that GHRP could be useful as provocative test on the diagnosis of GH deficiency. We compared the GH response to the maximal effective dose of Hexarelin (2 micrograms/kg i.v.), an hexapeptide belonging to GHRP family, with that of GHRH (1 microgram/kg i.v.) alone and combined with arginine (ARG, 0.5 g/kg i.v.), which likely acts via inhibition of hypothalamic somatostatin release. We studied 6 prepubertal (4 boys and 2 girls, age 2.6-12.2 yr) and 6 pubertal children with normal short stature (3 boys and 3 girls, age 10.3-14.4 yr) as well as 12 normal young adults (6 males and 6 females, age 22-30 yr) and 12 normal elderly subjects (6 males and 6 females, age 53-79 yr). In prepubertal children, the GH response to HEX (19.0 +/- 4.6 micrograms/l; 611.5 +/- 121.4 micrograms/l/h) was lower than that to GHRH (27.4 +/- 12.7 micrograms/l; 1209.0 +/- 590.9 micrograms/l/h) but this difference did not attain statistical significance. Both these responses were, in turn, lower (p < 0.05) than that to ARG + GHRH (57.9 +/- 15.1 micrograms/l; 2483.6 +/- 696.6 micrograms/l/h). In pubertal children, the GH response to HEX (67.6 +/- 12.7 micrograms/l; 2755.3 +/- 547.3 micrograms/l/h) was higher than that to ARG + GHRH (49.1 +/- 8.9 micrograms/l; 2554.1 +/- 356.6 micrograms/l/h) but this difference did not attain statistical significance; both these responses were, in turn, clearly higher (p < 0.05) than that to GHRH alone (23.1 +/- 7.9 micrograms/l; 1004.8 +/- 214.3 micrograms/l/h). In young adults, the GH response to HEX 60.9 +/- 8.0 micrograms/l; 2401.0 +/- 376.2 micrograms/l/h) was similar to that to ARG + GHRH (68.9 +/- 11.7 micrograms/l; 3035.7 +/- 466.6 micrograms/l/h) and both were clearly higher (p < 0.001) than that to GHRH alone (21.6 +/- 3.6 micrograms/l; 790.0 +/- 137.0 micrograms/l/h). In elderly subjects, the GH response to HEX (22.4 +/- 4.9; 855.0 +/- 199.0 micrograms/l/h) was higher (p < 0.01) than that to GHRH (3.6 +/- 0.8 micrograms/l; 151.8 +/- 24.6 micrograms/l/h) but lower (p < 0.05) than that to ARG + GHRH (48.1 +/- 4.6 micrograms/l; 1758.2 +/- 149.1 micrograms/l/h). In conclusion, GHRPs are a powerful stimulus of GH secretion in pubertal children and young adults only. On the other hand, the age-related variations in the GH response to GHRPs probably limit their reliability for the evaluation of GH releasable pool in prepubertal children and elderly subjects.

Reduced growth hormone (GH) responsiveness to combined GH-releasing hormone and pyridostigmine administration in the Prader-Willi syndrome

OBJECTIVE

It is unclear whether the blunted GH secretion in Prader-Willi Syndrome (PWS) is a true deficiency, or merely secondary to obesity. We have investigated the role of obesity in the blunted GH secretion in PWS.

DESIGN

We studied the GH response to a combined administration of GHRH (1 microgram/kg i.v. at 0 min) and pyridostigmine (PD) (60 and 120 mg by mouth for children and adults, respectively, at time -60 min), as well as the baseline IGF-I levels, in a group of patients with PWS. Two different control groups were studied with GHRH + PD using the same doses and methods as above: prepubertal and pubertal obese subjects, and prepubertal short normal children. Moreover, in 14 patients with PWS and in the group of short normals the GH response to at least two stimulation tests (insulin tolerance test, clonidine, L-dopa, arginine) had been previously determined.

PATIENTS

Twenty-two PWS patients (10 males and 12 females), 21 with essential obesity (11 males and 10 females), and eight short normal children (4 males and 4 females) were studied after obtaining informed consent.

MEASUREMENTS

Blood samples were taken at -60, -30 and 0 min and then 15, 30, 45, 60, 90 and 120 min after GHRH administration. Serum GH was measured in duplicate by IRMA, and IGF-I by RIA after acid ethanol extraction. Statistical analysis was performed by t-test for unpaired data, and analysis of variance for parametric or nonparametric data, where appropriate.

RESULTS

The GH response to GHRH + PD was significantly lower in PWS patients (AUC: mean +/- SE: 599 +/- 99 micrograms/l/h) if compared with either short normal children (3294 +/- 461 micrograms/l/h: P < 0.0001) or obese subjects (1445 +/- 210 micrograms/l/h: P < 0.005). Low IGF-I concentrations were found in all PWS patients, so that PWS group had mean IGF-I levels significantly lower than the other groups.

CONCLUSIONS

Our results showed that subjects with PWS had a reduced GH responsiveness to GHRH + PD associated with subnormal IGF-I levels. These findings suggested that short stature in PWS may be at least partially correlated to the presence of GH deficiency, and that impaired GH secretion is not secondary to obesity.

Variability in growth hormone stimulation tests

The diagnosis of growth hormone deficiency (GHD) in adulthood has become increasingly important because of the approved indication for growth hormone (GH) substitution therapy in such patients. While GH stimulation tests are superior to single measurements of other growth factors or spontaneous GH secretion in the diagnosis in adults, the reproducibility and specificity of GH stimulatory tests are often described to be low. This is also the case with the insulin tolerance test. Many external factors, such as fasting, physical activity, heat exposure and sleep, are known to influence GH secretion. The stimulatory or inhibitory effect of these factors on GH secretion might, therefore, influence the GH provocative test and contribute to the variability in response. Age and body composition are also known to influence GH secretion, and these factors must be considered when evaluating GH test responses. However, age-related cut-off levels for GHD have not been defined. Obesity is still a complicating factor in the diagnosis of GHD, even though some GH tests have been able to distinguish between obesity and true GHD. Based on these complicating factors, the parameters of GH stimulatory tests are recommended to be defined and standardized to optimize reproducibility and specificity. Furthermore, such tests should be performed only in patients with firm evidence of pituitary disease.

Serum insulin-like growth factor-I (IGF-I) and IGF binding protein-3 levels in children with precocious puberty treated with gonadotropin-releasing hormone analog without or in combination with cyproterone acetate

In order to assess the behavior of growth hormone, insulin-like growth factor-I (IGF-I) and IGF binding protein-3 (IGFBP-3) in girls with central precocious puberty treated with gonadotropin-releasing hormone (GnRH) analog-therapy, we studied 14 girls with this condition, the patients were subdivided into two groups, according to the therapy followed. Group A (n = 7; age 4.2-7.1 years) received GnRH analog in combination with cyproterone acetate, and Group B (n = 7; age 4.4-6.9 years) received long-acting analog alone. Before treatment, IGF-I levels were significantly increased compared to healthy age-matched children in the two groups (447 +/- 33 micrograms/l for Group A and 435 +/- 38 micrograms/l for Group B vs. control 175 +/- 78 micrograms/l; p < 0.01). Moreover, serum IGFBP-3 levels were significantly higher than the age-related reference range for IGFBP-3 (4478.2 +/- 178 micrograms/l for Group A and 4532.3 +/- 167 micrograms/l for Group B vs. control 2905 +/- 641 micrograms/l; p < 0.01). During the two years of gonadal suppression, Group A patients showed a significant decrease in IGF-I and IGFBP-3 levels, while in Group B there was no significant change in IGF-I; moreover, in Group B, IGFBP-3 levels increased significantly compared to baseline values during the first year of treatment (4532.3 +/- 167 micrograms/l vs. 5410.3 +/- 169 micrograms/l; p < 0.05) and decreased significantly at the end of the second year of treatment (3816.1 +/- 189 micrograms/l vs. 5410.3 +/- 169 micrograms/l; p < 0.01). Our study shows that the two different treatments of precocious puberty (with and without cyproterone acetate) have different effects on IGF-I and IGFBP-3, and suggests that these growth factors are under different metabolic regulation.

Is the persistence of isolated GH deficiency in adulthood predicted by anatomical hypothalamic-pituitary alterations?

The aim of this study was to verify the persistence in adulthood of GH deficiency diagnosed in childhood and treated with hGH in childhood and to study whether anatomical hypothalamic-pituitary alterations evaluated by magnetic resonance (MR) imaging could predict it. To this goal, in six GHD adults (3 males and 3 females aged 17.2-24.5 yr, BMI 21.8 +/- 1.3), we studied anterior pituitary hormone response to GHRH (1 microgram/kg iv)+pyridostigmine (120 mg po)+ GnRH (100 micrograms iv) +TRH (400 micrograms iv)+hCRH (100 micrograms iv) as well as brain MR imaging. In childhood, the diagnosis of severe isolated GHD had been done based on auxological findings as well as on GH response < 7 micrograms/L after two classical provocative stimuli. In the present study, hormonal responses showed the persistence of severe isolated GHD in 4 out of 6 patients (peak, mean +/- SEM: 3.8 +/- 0.6, range 2.6-4.8 micrograms/L). In these patients, IGF-I levels were found low or low-normal. In other 2 patients, a clear GH response to stimulation (peak: 51.3 and 43.0 micrograms/L, respectively) together with normal IGF-I levels were found. No other anterior pituitary hormone deficiency was present in all subjects. MR imaging showed pituitary hypoplasia in all patients with persistent GHD; in 2 out of them, pituitary stalk interruption and ectopic neurohypophysis was also present. On the other hand, MR imaging showed normal hypothalamo-pituitary morphology in the 2 subjects with normal somatotrope response. In conclusion, our present data indicate that testing with a potent stimulus such as GHRH+pyridostigmine is a reliable method to assess the persistence of GH deficiency which associates with anatomical hypothalamic-pituitary alterations at the MR imaging. Patients with transient GH deficiency in childhood and normal pituitary GH reserve in adulthood have normal hypothalamic-pituitary MR imaging.

Diagnosis of growth hormone deficiency

Many ways of evaluating the physiological state of hGH secretion exist, some of which have been touched upon and none of which has as yet proven infallible. Apart from important clinical features like history, physical data and growth rate, the diagnosis of altered pituitary function is based on tests and their interpretation. The physician responsible has to be informed on their effectiveness and pitfalls. Results should be interpreted in relation to developmental age (bone age) rather than chronological age. Research is under way to try to facilitate the diagnosis of varying degrees of alterations of hGH secretion. Reliability in predicting the effect of therapy with hGH is the ultimate aim in order to prevent unnecessary cost and disappointment for the patients. With the help of doctors involved in child care, such as physicians at kindergarten or school, it should be possible to start the slow process of investigating growth disorders at an early age.