Consensus statement on the diagnosis and treatment of children with idiopathic short stature: a summary of the Growth Hormone Research Society, the Lawson Wilkins Pediatric Endocrine Society, and the European Society for Paediatric Endocrinology Workshop

OBJECTIVE

Our objective was to summarize important advances in the management of children with idiopathic short stature (ISS).

PARTICIPANTS

Participants were 32 invited leaders in the field.

EVIDENCE

Evidence was obtained by extensive literature review and from clinical experience.

CONSENSUS

Participants reviewed discussion summaries, voted, and reached a majority decision on each document section.

CONCLUSIONS

ISS is defined auxologically by a height below -2 sd score (SDS) without findings of disease as evident by a complete evaluation by a pediatric endocrinologist including stimulated GH levels. Magnetic resonance imaging is not necessary in patients with ISS. ISS may be a risk factor for psychosocial problems, but true psychopathology is rare. In the United States and seven other countries, the regulatory authorities approved GH treatment (at doses up to 53 microg/kg.d) for children shorter than -2.25 SDS, whereas in other countries, lower cutoffs are proposed. Aromatase inhibition increases predicted adult height in males with ISS, but adult-height data are not available. Psychological counseling is worthwhile to consider instead of or as an adjunct to hormone treatment. The predicted height may be inaccurate and is not an absolute criterion for GH treatment decisions. The shorter the child, the more consideration should be given to GH. Successful first-year response to GH treatment includes an increase in height SDS of more than 0.3-0.5. The mean increase in adult height in children with ISS attributable to GH therapy (average duration of 4-7 yr) is 3.5-7.5 cm. Responses are highly variable. IGF-I levels may be helpful in assessing compliance and GH sensitivity; levels that are consistently elevated (>2.5 SDS) should prompt consideration of GH dose reduction. GH therapy for children with ISS has a similar safety profile to other GH indications.

Secretion of the adrenal androgen, dehydroepiandrosterone sulfate, during normal infancy, childhood, and adolescence, in sick infants, and in children with endocrinologic abnormalities

Serum concentrations of the adrenal androgen, dehydroepiandrosterone sulfate, were measured by radioimmunoassay in normal infants and children, in sick premature and full-term newborn infants, and in patients undergoing evaluation of the hypothalamic-pituitary-gonadal and -adrenal systems. Premature infants had significantly greater (p less than 0.001) levels of DHAS (263 +/- 40)[SE]migrong/dl) than did full-term infants (58.9 +/- 5.2) during the first ten days of life; further increments occurred in stressed "sick" infants. A gradual age- and maturity-related rise in serum concentrations of DHAS was observed during childhood with the earliest increase occurring prior to the onset of pubertal production of gonadal steroids. Serum levels of DHAS rose following administration of ACTH and were increased in patients with congenital adrenal hyperplasia, in whom rapid decrements followed treatment with dexamethasone. hCG or LH-RH treatment did not alter DHAS concentrations. These data suggest that direct secretion of DHAS by the adrenal gland and/or peripheral sulfation of DHA, rather than gonadal secretion, accounts for the majority of DHAS production. The involvement of adrenal androgens in the pubertal maturation of the reproductive endocrine system thus may be evaluated by quantitation of serum DHAS.

Responsivity of pituitary gonadotropes to luteinizing hormone-releasing factor in idiopathic precocious puberty, precocious thelarche, precocious adrenarche, and in patients treated with medroxyprogesterone acetate

One hundred micrograms synthetic luteinizing hormone-releasing factor (LRF) were administered to 13 girls and 2 boys with idiopathic precocious puberty, 3 girls with precocious thelarche, 2 girls with precocious adrenarche, and 5 children treated with medroxyprogesterone acetate (MPA). Luteinizing hormone (LH), follicle-stimulating hormone (FSH), and sex steroid responses were assessed. The mean readily releasable LH rose to a peak of 8.4 plus or minus 1. 8 ng/ml (LER 960) in the children with idiopathic precocious puberty and was significantly greater than in normal prepubertal (1.8 plus or minus 0.14) or pubertal children (4.9 ng/ml) (LER 869) was higher in precocious puberty but not significantly greater than in normal prepubertal (5.3 plus or minus 1.9) or pubertal girls (6.0 plus or minus 1.2). The mean concentration of plasma estradiol rose significantly above resting levels after LRF in the girls with idiopathic precocious puberty. The LH response in girls with precocious the larche was in the prepubertal range. In 4 of 5 children with sexual precocity treated with MPA, the LH release evoked by LRF was diminished.

Effects of zinc deficiency upon pituitary function in sexually mature and immature male rats

Serum pituitary levels of growth hormone (GH), thyrotropin (TSH), prolactin (PRL), luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured in sexually mature (adult) and sexually immature (juvenile) male rats who had been deprived of dietary zinc for 15 and 7 weeks, respectively. When compared to pair-fed control rats receiving a zinc supplemented diet, both the adult and juvenile zinc deficient rats had significantly lower body weights, tail lengths and ventral prostate weights. The testes of the sexually immature rats were also smaller than those of the pair-fed animals. In sexually mature, zinc deficient rats serum concentrations of GH and testosterone were significantly lower and serum LH levels significantly higher than in ad libitum fed control rats. Pituitary and hypothalamic levels of other hormones did not differ from values recorded in control animals. In sexually immature zinc deficient rats serum concentrations of GH were also significantly depressed; pituitary content and concentration of LH and pituitary and serum levels of FSH were significantly increased over control values. No discernible effects of zinc deficiency upon hyplthalamic content of LH-releasing hormone or serum concentrations of PRL or TSH were recorded in juvenile rats. Zinc deficiency has minimal effects upon the hypothalamic-pituitary axis of sexually mature rats. In sexually immature males, zinc deprivation leads to impairment of gonadal growth and increased synthesis and/or secretion of the pituitary gonadotropins.

Variable estimates of serum growth hormone concentrations by different radioassay systems

Many different assays are being used to measure serum GH concentrations in children with disorders of growth. We assessed four readily available methods to determine the comparability of the immunopotency estimates: standard double antibody RIA with pituitary standards from the National Hormone and Pituitary Program (assay 1) and from a commercial source (assay 2), a double antibody RIA with serum standards (assay 4), and a commercial immunoradiometric assay (assay 3). There was a high degree of relative correlation between assays (r = 0.95-0.98), but absolute potency estimates differed. Assays 1 and 2 were almost identical. Assay 3 yielded serum GH levels about 65% those of assay 1 or 2 and 80% those of assay 4. Assay 4 gave intermediate values between the low readings in assay 3 and higher values in assay 1 and 2. We conclude that substantial variation occurs in potency estimates in different GH assays. Such differences can affect the interpretation of many GH provocative and sampling studies.

Testicular leydig cell hyperplasia as a cause of familial sexual precocity

Testicular Leydig cell hyperplasia was observed in two brothers presenting with progressive sexual precocity at 2 yr of age. Virilization was shown to result from increased secretion rather than decreased clearance of gonadal testosterone. Testosterone hypersecretion appeared to be gonadotropin independent, as basal and gonadotropin-releasing hormone-induced serum LH concentrations were low by both RIA and bioassay. Adrenal steroidogenesis was demonstrated to be normal by ACTH stimulation, dexamethasone suppression, and split adrenal venous function tests. Testicular histology revealed immature reproductive structures in the 2 yr old, but advanced spermatogenesis in the 3 yr-old brother. The etiology of both Leydig cell hyperplasia and reproductive testicular maturation in the absence of significant gonadotropin secretion remains to be established.

The reproductive endocrine system in cystic fibrosis. I. Basal gonadotropin and sex steroid levels

Serum gonadotropin and sex steroid levels were measured in 106 patients with cystic fibrosis (CF), 46 males and 60 females, aged 8 to 24 years. The finding of delayed pubertal increments of serum gonadotropin and sex steroid levels in CF patients suggests late maturation of the reproductive endocrine system. Although pubertal changes in reproductive endocrine hormones in patients with CF appear to be temporally delayed, generally appropriate levels of these hormones are finally attained in most patients by the late teenage years. Delayed maturation of the reproductive endocrine system probably is secondary to hypothalamic-pituitary dysfunction, the result of chronic inanition.

Maternal diabetic control and hypertrophic cardiomyopathy in infants of diabetic mothers

Hypertrophic cardiomyopathy has been well documented in infants of diabetic mothers (IDMs). If this asymmetric septal enlargement is an anabolic result of fetal hyperinsulinemia triggered by maternal hyperglycemia during the third trimester, maternal glycosylated hemoglobin (HbA1) levels, an indicator of glycemic control, should then correlate positively at delivery with newborn ventricular septal thickness. In this study of 20 infants of well-controlled diabetic mothers, no relationship was observed between echocardiographic evidence of hypertrophic cardiomyopathy and maternal HbA1 levels. Seven babies (35%) exhibited exaggerated septal thickening, but none had cardiac-specific symptoms. Although 60 percent of the IDMs were large for gestational age and 45 percent demonstrated neonatal hypoglycemia, neither of these complications correlated with maternal HbA1. In this group of babies of well-controlled diabetic women, echocardiographic indicators of cardiomyopathy were common, but clinical evidence of cardiac embarrassment was not observed. Moreover, these data do not support third trimester maternal hyperglycemia as instrumental in the etiology of cardiomyopathy and other complications of IDMs.

Idiopathic short stature: management and growth hormone treatment

In the management of ISS auxological, biochemical, psychosocial and ethical elements have to be considered. In boys with constitutional delay of growth and puberty androgens are effective in increasing height and sexual characteristics, but adult height is unchanged. GH therapy is efficacious in increasing height velocity and adult height, but the inter-individual variation is considerable. The effect on psychosocial status is uncertain. Factors affecting final height gain include GH dose, height deficit in comparison to midparental height, age and first year height velocity. In case of a low predicted adult height at the onset of puberty, addition of a GnRH analogue can be considered. Although GH therapy appears safe, long-term monitoring is recommended.

Gonadotropin and testosterone measurements after estrogen administration to adult men, prepubertal and pubertal boys, and men with hypogonadotropism: evidence for maturation of positive feedback in the male

Nineteen male subjects were fiven five daily injections of 17beta-estradiol and circulating levels of estradiol (E2), testerone (T), and gonadotropins were determined by radioimmunoassay before, during, and after the steroid course. Peak levels of E2 attained during the 5 days of treatment ranged from 173-577 pg/ml. Four of seven normal adult men and one castrate man demonstrated suppression of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) with a subsequent rise in LH (positive feedback) while E2 levels remained elevated. A rise in T was associated with the LH increment in the four normal men. Nine pre-, early, or midpubertal boys and two men with hypogonadotropic hypogonadism displayed only gonadotropin suppression after E2 administration. The difference in LH response to estrogen (i.e., positive feedback) between the adult men with normal or elevated gonadotropin levels as compared with the endocrinologically normal boys is significant (P less than 0.01).

A multicenter study of the efficacy and safety of sustained release GH in the treatment of naive pediatric patients with GH deficiency

Treatment of naive children with GH deficiency has relied upon long-term replacement therapy with daily injections of GH. The daily schedule may be inconvenient for patients and their caregivers, possibly promoting nonadherence with the treatment regimen or premature termination of treatment. We studied a new sustained release GH formulation, administered once or twice monthly, to determine its efficacy and safety in this population. Seventy-four prepubertal patients with documented GH deficiency were randomized to receive sustained release recombinant human GH at either 1.5 mg/kg once monthly or 0.75 mg/kg twice monthly by sc injection in a 6-month open-label study. Efficacy was determined by growth data from 69 patients completing 6 months and 56 patients completing 12 months in an extension study. Growth rates were significantly increased over baseline and were similar for the two dosage groups. The mean (+/-SD) annualized growth rate (pooled data) was 8.4 +/- 2.1 cm/yr at 6 months, and the growth rate was 7.8 +/- 1.8 at 12 months compared with 4.5 +/- 2.3 at baseline. Standardized height, bone age, and predicted adult height assessments demonstrated catch-up growth without excessive skeletal maturation. Injection site-related events (including pain, erythema, and nodules) were the most commonly reported adverse events; no serious adverse events related to treatment were reported. Laboratory studies documented no accumulation of trough GH or IGF-I levels during treatment, nor did glucose intolerance or persistent hyperinsulinism develop. Sustained release recombinant human GH is safe and effective for long-term GH replacement in children with GH deficiency. Patients achieved similar growth velocities when sustained release GH was given once or twice monthly. The enhanced convenience of this dosage form may result in greater long-term adherence to the treatment regimen.

High dose recombinant human growth hormone (GH) treatment of GH-deficient patients in puberty increases near-final height: a randomized, multicenter trial. Genentech, Inc., Cooperative Study Group

GH production rates markedly increase during human puberty, mostly as an amplitude-modulated phenomenon. However, GH-deficient children have been dosed on a standard per kg BW basis similar to prepubertal children. This randomized study was designed to compare the efficacy and safety of standard recombinant human GH (rhGH) therapy (group I, 0.3 mg/kg x week) vs. high dose therapy (group II, 0.7 mg/kg x week) in GH-deficient adolescents previously treated with rhGH for at least 6 months. Ninety-seven children with documented evidence of GH deficiency (peak GH in response to stimuli, <10 ng/mL), with either organic or idiopathic pathology, were recruited. Both groups were matched for sex (group I, 42 males and 7 females; group II, 41 males and 7 females), age [group I, 14.0+/-1.6 (+/-SD) yr; group II, 13.7+/-1.6], standardized height (group I, -1.4+/-1.1; group II, -1.2+/-1.1), bone age (group I, 13.1+/-1.3 yr; group II, 13.1+/-1.3) etiology, maximum stimulated GH, previous growth rate, and midparental target height. All subjects were in puberty (Tanner stage 2-5) at study entry. Of the 97 subjects enrolled, 45 were treated for 3 yr or more; 48 completed the study. Of the subjects who discontinued the study, the most common reason was satisfaction with their height, although others discontinued for adverse events or personal reasons. The frequency of patients who discontinued was the same in both groups. The primary efficacy analysis was the difference between dose groups for near-adult height, defined as the height attained at a bone age of 16 yr or more in males and 14 yr or more in girls; all subjects who qualified were included in the analysis. This difference was statistically significant at 4.6 cm by analysis of covariance (ANCOVA; P < 0.001; n = 75). For subjects who received at least 4 yr of rhGH treatment, the difference between dose groups at that time point was 5.7 cm (by ANCOVA, P = 0.024; n = 20). The mean height SD score at near-adult height was -0.7+/-0.9 in the standard dose group and 0.0+/-1.2 in the high dose group. At 36 months the cumulative change in height (centimeters) was 21.5+/-5.3 cm (group I) vs. 25.1+/-4.9 (group II; P < 0.001, by ANCOVA); the change in Bayley-Pinneau predicted adult height was 4.8+/-4.2 cm (group I) vs. 8.4+/-5.7 (group II; P = 0.032). Median plasma IGF-I concentrations at baseline were 427 microg/L (range, 204-649) in group I and 435 microg/L (range, 104-837) in group II; at 36 months they were 651 microg/L (range, 139-1079) in group I vs. 910 microg/L (range, 251-1843) in group II (P = NS). No difference in change in bone age was detected between groups at any interval. High dose rhGH was well tolerated, with a similar safety profile as standard dose treatment and no difference in hemoglobin A1c or glucose concentrations between groups. In summary, compared to conventional treatment, high dose rhGH therapy in adolescents 1) increased near-adult height and height SD scores significantly, 2) did not increase the rate of skeletal maturation, and 3) appears to be well tolerated and safe. In conclusion, high dose rhGH therapy may have a beneficial effect in adolescent GH-deficient patients, particularly those who are most growth retarded at the start of puberty.

Pharmacokinetic and pharmacodynamic characteristics of a long-acting growth hormone (GH) preparation (nutropin depot) in GH-deficient children

Long-term GH replacement therapy is indicated for children with growth failure due to GH deficiency (GHD). We evaluated the feasibility of administering a long-acting GH preparation [Nutropin Depot (somatropin, rDNA origin) for injectable suspension] to prepubertal children with GHD by examining pharmacokinetic and pharmacodynamic response parameters after single or multiple doses. Data were collected from three studies involving 138 children treated with Nutropin Depot 0.75 mg/kg once per month, 0.75 mg/kg twice per month, or 1.5 mg/kg once per month. Twenty-two patients underwent intensive sampling to estimate mean peak serum GH concentrations (C(max)) and time to achieve C(max) for GH and IGF-I. Thereafter, weekly serum concentrations were measured and compared with baseline. C(max) and area under the curve were approximately proportional to the dose administered. Fractional area under the curve data indicate that at least 50% of GH exposure occurs during the first 2 d after administration. Serum GH levels remained above 1 microg/liter for 11-14 d. IGF-I levels remained above baseline for 16-20 d, but increases were not proportional to dose. After multiple doses over a 6-month period, peak and trough concentrations showed no progressive accumulation of GH, IGF-I, or IGF binding protein-3. Nutropin Depot administration once or twice per month provides serum levels of GH and IGF-I expected to promote growth, without accumulation of GH, IGF-I, or IGF binding protein-3, in children with GHD.

Vitamin D metabolites in adolescents and young adults with cystic fibrosis: effects of sun and season

To assess mineral metabolism in patients with cystic fibrosis and to study the effects of season and sunlight exposure on generation of vitamin D metabolites, we quantified serum levels of calcidiol and calcitriol, other measures of bone metabolism, and radiographic bone mass in 20 adolescents and young adults with CF and 20 age-matched normal volunteers. Levels of calcidiol were lower in patients with CF than in controls and lower in Massachusetts than in Arizona in both study groups. Controls in Arizona had higher (P less than 0.05) levels of calcitriol than in Massachusetts throughout the year. All control subjects in both states had higher levels of calcitriol than did patients with CF. Patients in Massachusetts had significantly lower levels of calcitriol in winter than in summer. Summer levels of calcitriol in CF were significantly higher in Massachusetts than in Arizona; during winter, lower levels were found in Massachusetts than in Arizona. Mean bone density in patients with CF was 88% and 89% of normal American standards in Massachusetts and Arizona, respectively. These data indicate a seasonal, sunlight-related influence on levels of vitamin D metabolites in patients with CF receiving approximately 1000 IU vitamin D per day. Older patients with CF with progressively diminishing sunlight exposure may be at increased risk for development of osteopenia. The detected radiographic abnormalities of bone mineralization may also be related to malabsorptive deficiencies of calcium and phosphorus.

The response of pituitary gonadotropes to synthetic LRF in children with glucocorticoid-treated congenital adrenal hyperplasia: lack of effect of intrauterine and neonatal androgen excess

Previous studies have demonstrated that the secretory reserve of the pituitary gland during childhood and adolescence is characterized by an age-related increase in LH secretion and a sex dichotomy of FSH secretion evoked by LRF. To determine if prenatal and neonatal androgen excess alters hypothalamic-pituitary-gonadal function, as in the neonatally androgenized rodent, we assessed pituitary sensitivity to 100 mug synthetic LRF in 9 girls and 2 boys with glucorticoid-treated congenital virilizing adrenal hyperplasia (CAH). In the 7 prepubertal girls with CAH, plasma LH following LRF rose to 2.0 plus or minus 0.4 (SE) ng/ml (LER 960) and did not differ from normal prepubertal children (1.7 plus or minus 0.1) and was lower (P less than 0.002) than in normal pubertal children (4.9 plus or minus 0.3). The 2 pubertal girls had LH rises in the pubertal range. In the 2 boys with CAH, the one with the more advanced bone age, 11-6/12 yr, developed true precocious puberty following initiation of cortisone treatment and had a pubertal LRF-evoked LH release on 3 occasions; the more immature boy, bone age 10, had a prepubertal LH rise. In the 7 prepubertal girls with CAH, plasma FSH rose to 8.1 plus or minus 1.6 (SE) ng/ml (LER 869), which did not differ from normal prepubertal girls (5.3 plus or minus 1.9), but was significantly (P less than 0.001) greater than in normal prepubertal boys (2.9 plus or minus 0.4). In these girls with CAH, basal plasma T (27.4 plus or minus 4.0 (SE) ng/dl) and 17-OHP (2703 plus or minus 1143 (SE) ng/dl) were greater than in prepubertal children, but plasma E1 and E2 were in the normal range. The pubertal boy had plasma T, E1, and E2 levels appropriate for his degree of sexual maturation. The results suggest: (1) age-related LH secretion evoked by LRF in glucocorticoid-treated CAH is appropriate for skeletal maturation; (2) the sex dichotomy of FSH secretion following LRF is preserved in CAH despite intrauterine and variable postnatal exposure to excess androgen and continuing slightly elevated plasma T during childhood; and (3) precocious puberty may follow initiation of cortisone treatment in a child with CAH whose bone age and secretory reserve of pituitary gonadotropins are in the pubertal range.

Absence of nonclassical congenital adrenal hyperplasia in patients with precocious adrenarche

We studied 31 patients (28 girls and 3 boys), ranging in age from 3.2-7.9 yr, with precocious adrenarche defined by the presence of early sexual hair development, no signs of virilization, and bone age within +3 SD of the mean for chronological age. To determine if this symptom complex stemmed from any form of nonclassical (late-onset) congenital adrenal hyperplasia, an ACTH stimulation test was performed on each patient using a standard 0.25-mg dose of Cortrosyn, given as an iv bolus. Twelve pubertal children (7 girls and 5 boys) and 18 prepubertal children (11 girls and 7 boys) served as normal controls. Baseline and stimulated 17-hydroxypregnenolone (17-OHPreg), 17-hydroxyprogesterone, (17-OHP), 11-deoxycortisol, dehydroepiandrosterone, androstenedione, testosterone, and cortisol levels were measured. Using published nomogram standards for serum 17-OHP response to ACTH, no child with precocious adrenarche was diagnosed as having nonclassical 21-hydroxylase deficiency. Eight girls, however, had a stimulated 17-OHP value that exceeded the mean response for pubertal and prepubertal controls by more than +2 SD [range, 295-670 ng/dL (8.94-20.3 nmol/L)]. Stimulated 11-deoxycortisol values [less than 400 ng/dL (11.6 nmol/L)] ruled out any cases of nonclassical 11 beta-hydroxylase deficiency. No patient had nonclassical 3 beta-hydroxysteroid dehydrogenase deficiency, as defined by both the stimulated 17-OHPreg and the 17-OHPreg/17-OHP ratio to be more than +2 SD above the mean for pubertal children [1354 ng/dL (41.0 nmol/L) and 10.4, respectively]. In conclusion, we could not provide any biochemical evidence for nonclassical congenital adrenal hyperplasia in a large group of children with precocious adrenarche.