Somatomedin-C in accelerated growth of children with precocious puberty

The alteration of IGF-1 levels and relationship between IGF-1 levels and growth velocity during GnRH analogue therapy

Background Some studies have examined the effect of gonadal suppression on insulin-like growth factor-1 (IGF-1) levels and the growth velocity (GV) with conflicting results. Methods Forty-four girls treated with gonadotropin-releasing hormone analogue (GnRHa) for central precocious puberty (CPP) were included in the study. IGF-1 levels were examined at the beginning and after 12 months of treatment. Results IGF-1 and IGF-1 standard deviation score (SDS) according to chronological age (CA-IGF-1 SDS) at diagnosis were positively correlated with chronological age (CA), anthropometric measurements, stage of puberty, bone age (BA), BA-CA, follicle-stimulating hormone (FSH), luteinising hormone (LH), oestradiol, uterus length, endometrium thickness and ovarian volume (OV) at diagnosis (p < 0.05). There was no significant difference in IGF-1 levels after treatment. However, there was a negative correlation between ΔIGF-1 SDS and IGF-1 level, CA-IGF-1 SDS and BA-IGF-1 SDS at diagnosis (p < 0.05). There was no correlation between GV and IGF-1, ΔIGF-1. GV was negatively correlated with basal LH level at diagnosis (p = 0.008, r = -0.397). Peak LH levels of the patients who had GV-SDS < 0 were more suppressive than those of the patients who had GV-SDS > 0 after 12 months of treatment. Conclusions It was determined that the IGF-1 level and CA-IGF-1 SDS at baseline were correlated with more advanced pubertal stage prior to treatment. Initiation of treatment with a relatively high level of IGF-1 increased the risk of a decrease in the IGF-1 level. Likewise, the initiation of treatment with a relatively high LH level may increase the risk of low GV, but low GV was not related to the IGF-1 level. Increased sex steroid suppression may increase the risk of low GV.

Circulating ghrelin levels in girls with central precocious puberty are reduced during treatment with LHRH analog

Decreased levels of ghrelin have been measured in growing children during puberty. No data are available for girls with central precocious puberty (CPP).

AIMS

To explore ghrelin changes before, during, and after GnRH analog treatment in girls with CPP.

SUBJECTS AND METHODS

A sample of 20 Caucasian girls (8.08 +/- 0.65 years of age) with CPP was recruited. Height and weight, bone age, LH, FSH, 17beta estradiol (E(2)), and ghrelin were measured before starting treatment with GnRH analog, 18 months after therapy began and again 6 months after therapy discontinuation.

RESULTS

LH and E(2) serum levels decreased significantly during treatment (2.45 +/- 2.03 vs 0.67 +/- 0.49 UI/l, P < 0.01 and 28.17 +/- 9.7 vs 15 pmol/l, P < 0.01 respectively), returning to baseline levels after the discontinuation of therapy (4.75 +/- 1.66 UI/l and 29.23 +/- 6.99 pmol/l respectively). LH peaked following LHRH stimulation significantly (P < 0.01) decreased during treatment (24.45 +/- 14.17 vs 1.3 +/- 0.18 UI/l) and then increased after therapy discontinuation (12.58 +/- 6.09, P < 0.01). Ghrelin decreased significantly (P < 0.05) during treatment (1849 +/- 322 vs 1207 +/- 637 pg/ml), and increased, though not significantly (P = 0.09) after therapy withdrawal (1567 +/- 629 pg/ml).

CONCLUSIONS

Contrary to what is expected in physiologic puberty, where ghrelin is progressively reduced, the prepubertal hormone milieau induced by GnRHa treatment in patients suffering from central precocious puberty (CPP) did not promote an increase in ghrelin circulating levels. Therefore, in CPP, ghrelin secretion seems to be independent from pubertal development per se. Concomitant estrogen suppression during treatment may play a potential role in the regulation of ghrelin secretion in these girls.

Fundamental limits on longitudinal bone growth: growth plate senescence and epiphyseal fusion

Longitudinal bone growth occurs rapidly in early life but then slows and, eventually, ceases. The decline in growth rate is caused primarily by a decrease in the rate of chondrocyte proliferation and is accompanied by structural changes in growth plate cartilage. This programmed senescence does not appear to be caused by hormonal or other systemic mechanisms but is intrinsic to the growth plate itself. In particular, recent evidence indicates that senescence might occur because stem-like cells in the resting zone have a finite proliferative capacity, which is exhausted gradually. In some mammals, including humans, proliferative exhaustion is followed by epiphyseal fusion, an abrupt event in which the growth plate cartilage is replaced completely by bone.

Serum IGF-I and IGFBP-3 concentrations do not accurately predict growth hormone deficiency in children with brain tumours

OBJECTIVE

The growth hormone (GH)-dependent growth factors insulin-like growth factor-I (IGF-I) and IGF-binding protein-3 (IGFBP-3) may be superior to provocative GH testing in diagnosing GH deficiency (GHD) in children. In adults with brain tumours (BT) and GHD, however, provocative GH testing more accurately reflects GHD than either IGF-I or IGFBP-3. We assessed growth factor levels in children with GHD due to BT with respect to brain tumour type, pubertal stage, growth velocity, bone age delay, and body mass index (BMI).

DESIGN

Retrospective case review of all patients followed at our centre with GHD following treatment of BT.

PATIENTS

72 children (51 M, 21 F) with BT diagnosed with GHD by clinical and auxological criteria, including provocative GH testing, in whom pre-GH treatment IGF-I and IGFBP-3 levels were obtained.

MEASUREMENTS

Auxological data, including height, weight, growth velocity, and pubertal stage; and biochemical data, including GH response to provocative GH testing and pre-GH treatment serum IGF-I and IGFBP-3 concentrations.

RESULTS

IGF-I levels were normal (above -2 SD) in 19 of 70 children (27%), and IGFBP-3 levels were normal in 21 of 42 (50%). In children with GHD, pubertal stage correlated significantly with both IGF-I (r = 0.328, p < 0.006) and IGFBP-3 (r = 0.364, P < 0.02). Normal IGF-1 levels were found in 1/15 children with craniopharyngioma (Cranio) (7%), 10/30 with primitive neuroectodermal tumours (PNET) (33%), and 5/12 children with hypothalamic/chiasmatic glioma (HCG) (42%) (P < 0. 05). IGFBP-3 levels were normal in 4/13 Cranio patients (31%), 8/15 PNET patients (53%), and 6/8 HCG patients (75%) (P = ns). Tanner staging varied significantly among tumour types: mode = 1 for Cranio and PNET vs. mode = 3 for HCG (P < 0.03). BMI did not differ between patients with low vs. normal growth factor levels.

CONCLUSIONS

Low IGF-I levels were more predictive of growth hormone deficiency than low IGFBP-3 levels in our brain tumour patients, but both were poor predictors of growth hormone deficiency in children with hypothalamic-chiasmatic glioma and in pubertal children. Serum IGF-I and IGFBP-3 levels, therefore, do not always reflect growth hormone deficiency in children with brain tumours, particularly in those with hypothalamic-chiasmatic glioma or those already in puberty.

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.

Two-year results of treatment with depot leuprolide acetate for central precocious puberty

We report results from 2 years of therapy with the long-acting form of the gonadotropin-releasing hormone (GnRH) analog leuprolide acetate, which was previously reported in short-term trials to be efficacious in the treatment of central precocious puberty. Thirteen girls and two boys, aged 1.9 to 9.7 years, who satisfied clinical criteria including GnRH-stimulated luteinizing hormone (LH) greater than 10 IU/L (mean radioimmunoassay LH, 29.1 +/- 5.54 IU/L), received depot leuprolide, 6 to 15 mg intramuscularly every 4 weeks. Estradiol (or testosterone), insulin-like growth factor I, and GnRH-stimulated gonadotropins were obtained at baseline, at 2 months, and at 6-month intervals with bone age determinations. Pubertal progression ceased in all patients, and menses did not occur. Mean increase in height during therapy was 5.77 +/- 2.0 cm/yr. Predicted adult height increased over baseline by 5.52 +/- 1.16 cm at 18 months. Mean estradiol values in the girls declined from 3.3 +/- 0.6 to 0.60 +/- 0.03 ng/dl, with no overlap of baseline and treatment values. The mean basal LH value was unchanged by therapy; mean basal and peak LH values for all follow-up GnRH stimulation tests were 4.05 +/- 0.57 and 4.95 +/- 0.70 IU/L, respectively. Basal and peak follicle-stimulating hormone (FSH) values were suppressed from 4.10 +/- 0.62 and 10.06 +/- 1.34 IU/L, respectively, to generally undetectable levels (< 1). Comparison with untreated control patients suggested that basal LH did not completely return to prepubertal levels, whereas FSH levels were suppressed below prepubertal levels. Estradiol, FSH, and LH levels reached their nadir by 2 months; in contrast, mean serum levels of insulin-like growth factor I progressively declined from +0.57 +/- 0.19 SD score to -0.06 +/- 0.22 SD score at 24 months. Two girls were withdrawn from the study because of reactions at injection sites, with apparent sterile abscess formation in one patient. This study provides evidence that (1) long-term treatment with depot leuprolide is characterized by immediate and sustained laboratory and clinical suppression, (2) GnRH-stimulated LH and random FSH and estradiol concentrations are useful laboratory measures of efficacy, and (3) the progressive increase in predicted adult height is temporally associated with decreased serum levels of insulin-like growth factor I and striking deceleration of bone age advancement.

Long-term results with a slow-release gonadotrophin-releasing hormone agonist in central precocious puberty. Dutch-German Precocious Puberty Study Group

As part of an ongoing international multicentre study, 19 children (14 girls, 5 boys) with central precocious puberty (CPP) were treated with a slow-release gonadotrophin-releasing hormone (GnRH) agonist, triptorelin, for 4 years. After 3 years of treatment, height velocity stabilized at 4.0 cm/year. Predicted adult height (mean +/- SD) increased from 158.9 +/- 6.8 to 164.9 +/- 6.6 cm in girls (n = 14, p less than 0.01), and from 174.4 +/- 18.5 to 184.3 +/- 17.1 cm in boys (n = 4, p less than 0.05). In 12 additional girls who had started the multicentre study but discontinued triptorelin treatment after 2.2 +/- 0.5 years, menses started 9.8 +/- 3.7 months after cessation of treatment in all but one patient. Height velocity increased over the first 6 months after discontinuation of treatment, from 3.6 +/- 0.1 to 5.4 +/- 2.5 cm/year, and remained higher than pretreatment values in the second 6 months, but decreased subsequently. Bone maturation increased, and no significant improvement in predicted adult height was observed. For auxological reasons, therefore, it may be advisable to continue triptorelin treatment for as long as possible. Concomitant growth hormone (GH) therapy was initiated in three girls with CPP with height velocities of 3.2-3.6 cm/year after 3 years of treatment with triptorelin and predicted adult heights of less than the third centile for Dutch girls. Prior to the administration of GH, all patients had subnormal 24-hour GH profiles and GH responses to arginine provocation. GH treatment increased height velocity markedly in all girls, and improved predicted adult height.(ABSTRACT TRUNCATED AT 250 WORDS)

Preserving adult height potential in girls with idiopathic true precocious puberty

We designed a prospective study of height potential in girls with idiopathic precocious puberty, comparing the presenting features of girls with and without evidence of reduced adult height potential. The 14 girls with impaired adult height prognoses (group 1) were reexamined after treatment with a gonadotropin releasing hormone agonist, nafarelin. The seven girls with the prognosis of unimpaired height (group 2) were followed without therapy. We found that the group could be distinguished at initial examination by the greater bone age/height age ratio of group 1 (mean +/- SEM: 1.4 +/- 0.06 vs 1.0 +/- 0.05; p less than 0.005) and by the greater difference between predicted height and target height in group 1. The mean predicted height in group 1 was significantly less than the mean target height (150.7 +/- 2.1 vs 165.4 +/- 3.0 cm; p less than 0.005), whereas the mean predicted and target heights in group 2 were similar (165.4 +/- 3.0 vs 164.3 +/- 2.1 cm). Initial estradiol levels were also greater in group 1 than in group 2 (21.6 vs 10.6 pg/ml; p less than 0.05), although this difference was not sustained during follow-up. In group 1, nafarelin therapy suppressed the pituitary-gonadal axis, and although there was a transient reduction in height potential in girls with the youngest bone ages during the first 6 months of therapy, 2 years of treatment slightly improved predicted heights from 150.7 +/- 2.1 to 152.7 +/- 2.0 cm (p less than 0.05). Height predictions also increased without therapy during the 2-year observation period in group 2, from 165.4 +/- 3.0 to 168.7 +/- 4.1 cm (p less than 0.05). Our data indicate that gonadotropin releasing hormone agonist therapy preserves height potential in girls with an initially impaired height prognosis, and that height potential is preserved without therapy in those with a good initial height prognosis.

Gonadotrophin-releasing hormone agonist treatment of central precocious puberty: an analysis of growth data in a developmental context

Growth and skeletal maturation was assessed in 83 girls with central precocious puberty (CPP) during pituitary-gonadal suppression induced by treatment with a gonadotrophin-releasing hormone agonist (GnRHa). The mean pretreatment chronological age (CA) was 6.3 years and the mean bone age (BA) was 10.6 years. During the suppression of gonadal sex steroid secretion, mean height velocity (HV) decreased from a pretreatment value of 10.8 cm/year to 5.9 (year 1, n = 83), 4.9 (year 2, n = 72), 4.2 (year 3, n = 45), and 4.4 (year 4, n = 23) cm/year. During each interval, there was a negative correlation between HV and the pretreatment BA. In addition, the rate of skeletal maturation was reduced during GnRHa treatment (delta BA/delta CA = 0.6 +/- 0.1 over 3 years, n = 45). The rate of skeletal maturation during therapy was also negatively correlated with pretreatment BA. Predicted adult stature, based upon zeta-scores of height for BA, increased significantly and progressively during therapy but the changes in height SDS for BA varied significantly. Since HV, delta BA/delta CA, and the change in height SDS for BA (delta HT SDS for BA) during pituitary-gonadal suppression all correlated with the initial degree of skeletal maturation, the effect of GnRHa therapy on final adult height in children with CPP will be best understood if growth data are assessed within a developmental framework.

Precocious puberty in girls: early diagnosis of a slowly progressing variant

An attempt was made to identify the less severe cases of precocious puberty and to describe their natural course. A group of 17 girls with precocious puberty and a bone age advance over chronological age of less than two years (group 1) was compared with a group of 19 patients with severe precocious puberty and bone age advance of two years or more (group 2). Mean (SEM) plasma oestradiol concentrations were 82 (30) pmol/l and 164 (21) pmol/l (p less than 0.05), vaginal maturation indexes were 16 (5) and 41 (4), and plasma somatomedin C concentrations were 1.0 (0.2) U/ml (n = 8) and 2.1 (0.3) U/ml (n = 16) in groups 1 and 2, respectively. The time between onset and diagnosis of secondary sexual characteristics was about one year in both groups. After two years' follow up the untreated patients in group 1 had maintained their predicted final height. These changes were in contrast to those observed at first examination in patients in group 2 who had a mean (SD) predicted final height of -1.3 (0.2) and a mean bone age advance of 3.0 (0.2) years. These data show that bone age advance to chronological age, and plasma somatomedin C concentrations measured at initial evaluation are helpful in identifying less severe and potentially slow progressing forms of central precocious puberty.

Growth hormone deficiency impedes the rise in plasma insulin-like growth factor I levels associated with precocious puberty

We tested the hypothesis that growth hormone (GH) mediates the rise in insulin-like growth factor I (IGF-I) concentrations in children with precocious puberty. We studied three groups of patients. Group 1 included six children with GH deficiency and precocious puberty (precocious GH-deficient); group 2 included 10 GH-sufficient patients with idiopathic true precocious puberty (precocious GH-sufficient); and group 3 included 9 prepubertal children with GH deficiency (prepubertal GH-deficient). Growth rates, pubertal status, and plasma IGF-I concentrations were determined at regular intervals. The precocious children with GH deficiency had a mean (+/- SD) growth rate of 7.2 +/- 2.1 significantly below that of the precocious GH-sufficient patients (10.5 +/- 2.5 cm/yr, p less than 0.05) but above that of the prepubertal GH-deficient children (3.9 +/- 1.4 cm/yr, p less than 0.05). The mean IGF-I concentration in the precocious GH-deficient children was 0.77 +/- 0.39 U/ml, significantly lower than the mean level of 2.2 +/- 0.67 U/ml in the precocious GH-sufficient patients (p less than 0.01). However, precocious GH-deficient patients had significantly higher IGF-I values than the prepubertal GH-deficient children (0.24 +/- 0.10 U/ml, p less than 0.05). IGF-I values did not rise with the onset of precocious puberty in four of the precocious GH-deficient children evaluated before and after the development of precocious puberty. However, three patients who began GH treatment did have a rise in plasma IGF-I concentrations to levels of 1.2, 3.4, and 3.7 U/ml, respectively. These findings are compatible with the concept that sex steroids increase IGF-I levels in precocious puberty primarily by increasing GH production. A small but direct effect of sex steroids on IGF-I production may also exist. The onset of precocious puberty in children with organic GH deficiency may mask the abnormal growth pattern of these children and delay diagnosis; determinations of plasma IGF-I concentrations may be helpful in assessing the GH status of these patients.

Long-term treatment of central precocious puberty with an intranasal LHRH analogue: control of pituitary function by urinary gonadotropins

Daily subcutaneous doses of luteinizing hormone-releasing hormone (LHRH) analogues are a well-established therapy for gonadotropin-dependent precocious puberty. Reports on intranasally administered analogues, however, are controversial. We studied the effect of intranasal D-Ser(TBU)6-LHRH(BUS) on growth rate, skeletal maturation, and urinary gonadotropins in five girls and one boy with central precocious puberty (CPP) who had been treated for 1.4-2.3 years (mean 1.9). Because of the potential antifertility effects of LHRH analogues, testicular histology was analysed in the boy. In the five children with accelerated growth, the bone age-related velocity of height gain decreased from 10.58 +/- 2.77 to 5.82 +/- 1.8 cm/year (means +/- SD, P less than 0.01), and the ratio of change in bone age to change in chronological age fell below 1. Basal luteinizing hormone (LH), and LHRH-stimulated LH and follicle stimulating-hormone, at pubertal levels before treatment, decreased significantly in all children, normalizing in four (P less than 0.04). During therapy, pituitary function was best controlled by urinary LH, which correlated with clinical data. After 13 months of therapy, testicular histology showed degenerated Sertoli cells, and absence of B- and Ap-spermatogonia and of primary spermatocytes in the boy. We conclude that: (1) Efficient long-term suppression of central precocious puberty--including accelerated growth and skeletal maturation--can be maintained by intranasal dosage of BUS. (2) Urinary LH reflects pituitary function and proves to be a reliable guide to adjustment of the LHRH-analogue dose regimen.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth hormone secretory dynamics in children with precocious puberty

We investigated whether an increase in growth hormone secretion contributed to the growth spurt in children with precocious puberty by measuring the 24-hour profile of serum growth hormone in 51 patients with central precocious puberty. Girls with central precocious puberty had significantly greater mean 24-hour levels of growth hormone in comparison with normal prepubertal girls (5.1 +/- 0.5 SEM vs 3.4 +/- 0.3 ng/mL, P less than 0.005). Mean 24-hour growth hormone levels did not differ significantly between boys with central precocious puberty and normal prepubertal boys (4.4 +/- 1.2 vs 3.0 +/- 0.4 ng/mL). Serum somatomedin C levels were significantly correlated with mean 24-hour growth hormone levels in the girls only. Height age advancement (expressed as height age/chronologic age) was significantly correlated with mean 24-hour growth hormone levels in both boys and girls with central precocious puberty. We conclude that spontaneous 24-hour growth hormone secretion in girls with precocious puberty is greater than that of normal prepubertal girls and may mediate at least in part the increased growth rate in this disorder.

Treatment of precocious puberty in the McCune-Albright syndrome with the aromatase inhibitor testolactone

The McCune-Albright syndrome is characterized by café au lait spots, fibrous dysplasia of bones, and sexual precocity. Girls with precocious puberty due to this syndrome have episodic increases in serum estrogen levels together with the formation of large ovarian cysts. The serum gonadotropin levels are typically suppressed, and the precocious puberty has not responded to treatment with long-acting analogues of luteinizing hormone-releasing hormone (LHRH). Encouraged by our initial success in a pilot study of one patient, we have now treated five girls with the McCune-Albright syndrome with the aromatase inhibitor testolactone, which blocks the synthesis of estrogens. Testolactone decreased the levels of circulating estradiol (P less than 0.05) and the ovarian volume (P less than 0.05), and there was a return to pretreatment levels after testolactone was stopped. During treatment, the peak responses of luteinizing hormone and follicle-stimulating hormone to stimulation by LHRH rose above suppressed pretreatment levels--significantly above pretreatment levels for follicle-stimulating hormone (P less than 0.02)--and then returned to pretreatment levels after testolactone was discontinued. Growth rates fell in three patients during treatment but could not be assessed in the other two because of bone deformities. The mean rate of bone maturation decreased and menses stopped in three of the four girls who were menstruating regularly. We conclude that testolactone is an effective treatment of precocious puberty in the McCune-Albright syndrome.

Growth hormone neurosecretory dysfunction

The basis for understanding clinical disorders in the neuroregulation of GH secretion is derived from the complexity of the CNS-hypothalamic-pituitary axis. Studies in animals and humans demonstrate an anatomic, physiological and pharmacological evidence for neurosecretory control over GH secretion including neurohormones (GRH, somatostatin), neurotransmitters (dopaminergic, adrenergic, cholinergic, serotonergic, histaminergic, GABAergic), and neuropeptides (gut hormones, opioids, CRH, TRH, etc). The observation of a defect in the neuroregulatory control of GH secretion in CNS-irradiated humans and animals led to the hypothesis of a disorder in neurosecretion, GHND, as a cause for short stature. We speculate that in this heterogeneous group of children a disruption in the neurotransmitter-neurohormonal functional pathway could modify secretion ultimately expressed as poor growth velocity and short stature.