Pathophysiology, assessment and management of the child with growth hormone resistance.

Defects in the growth hormone (GH)-insulin-like growth factor (IGF)I axis may cause GH resistance characterized by IGFI deficiency and growth failure. The range of defects causing GH resistance is broad as are their biochemical and phenotypical characteristics. We propose that GH-IGFI axis defects form a continuum of clinical and biochemical effects ranging from GH deficiency to GH resistance. The pathophysiology of GH resistance is described followed by a scheme for investigation of the child with severe short stature and normal GH secretion. We critically discuss GH therapy for such patients and define acceptable growth responsiveness. Finally we discuss therapy with IGF-I within the limits of the USA Food and Drug Administration and European Medicines Agency labels for GH resistance.

Role of steroidogenic acute regulatory protein in adrenal and gonadal steroidogenesis.

Congenital lipoid adrenal hyperplasia is an autosomal recessive disorder that is characterized by impaired synthesis of all adrenal and gonadal steroid hormones. In three unrelated individuals with this disorder, steroidogenic acute regulatory protein, which enhances the mitochondrial conversion of cholesterol into pregnenolone, was mutated and nonfunctional, providing genetic evidence that this protein is indispensable normal adrenal and gonadal steroidogenesis.

H-y antigen: expression in human subjects with the testicular feminization syndrome.

Androgen-insensitive subjects with a 46,XY karotype develop as phenotypic females despite presence of testes. The white blood cells of these females type H-Y antigen-positive indicate that expression of the H-Y cell surface component is androgen-independent.

Seven years of safety and efficacy of the recombinant human growth hormone Omnitrope in the treatment of growth hormone deficient children: results of a phase III study.

AIM: This phase III clinical study in growth hormone deficiency (GHD) children with growth retardation was designed to compare efficacy and safety of Omnitrope((R)) with Genotropin((R)) and assess the long-term safety and efficacy of Omnitrope((R)). The results of 7 years of treatment with Omnitrope((R)) are presented. PATIENTS AND METHODS: Eighty-nine treatment-naïve, prepubertal children with GHD were randomized (part 1) to Omnitrope((R)) lyophilisate (group A, n = 44) or Genotropin((R)) (group B, n = 45) for 9 months and received a subcutaneous dose of 0.03 mg/kg/day. In part 2, patients receiving Omnitrope((R))lyophilisate continued the same treatment for a further 6 months, while patients on Genotropin((R)) were switched to Omnitrope((R)) liquid for the subsequent 6 months. In part 3, patients in both groups received Omnitrope((R))liquid for a period up to 69 months. RESULTS: The development of the 4 auxological parameters (height, height SD score, height velocity and height velocity SD score) and IGF-1 and IGFBP-3 levels were comparable between both groups of patients and confirmed the well-known growth response of GHD children to recombinant human GH treatment. Omnitrope((R)) was well tolerated and safe over 7 years of treatment. CONCLUSION: The clinical comparability between Omnitrope((R)) and Genotropin((R)) was demonstrated within 9 months of treatment. Long-term safety and efficacy of 7 years of treatment with Omnitrope((R)) was proven.

First two years' response to growth hormone treatment in very young preterm small for gestational age children.

BACKGROUND: Growth hormone (GH) is a therapeutic option for small for gestational age (SGA) children without spontaneous catch-up. There are few reports on preterm SGA children. Prematurity is an additional risk factor for adult short stature. AIM: To describe GH efficacy in preterm SGA patients. METHODS: Twenty-five preterm SGA patients, 2-4 years old, treated with GH 0.066 mg/kg/day, were compared with 14 age-matched preterm SGA historical controls. Height, weight, IGF-I, IGFBP-3, fasting glucose and insulin were measured every 6 months. RESULTS: At start of GH treatment, mean height and weight were -2.4 and -2.4 SDS, respectively. There was a significant increment in height SDS of 1.3 and 2.1 during the 1st and the 2nd year of GH therapy, respectively. There was no significant difference between the progression of chronological and bone ages. A significant increase in IGF-I, IGFBP-3 and molar ratio was observed during GH therapy. There was no difference in glucose, insulin or HOMA-IR index. CONCLUSION: We showed for the first time that the height increment of preterm SGA with GH treatment is similar to that described in other studies with term SGA patients. Therefore, short-term GH treatment in a subset of preterm SGA patients between 2-4 years of age was able to promote adequate growth recovery with no excessive bone age acceleration or adverse effects on carbohydrate metabolism.

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.

Premature adrenarche--normal variant or forerunner of adult disease?

Adrenarche is the puberty of the adrenal gland. The descriptive term pubarche indicates the appearance of pubic hair, which may be accompanied by axillary hair. This process is considered premature if it occurs before age 8 yr in girls and 9 yr in boys. The chief hormonal product of adrenarche is dehydroepiandrosterone (DHEA) and its sulfated product DHEA-S. The well documented evolution of adrenarche in primates and man is incompatible with either a neutral or harmful role for DHEA and implies most likely a positive role for some aspect of young adult pubertal maturation and developmental maturation. Premature adrenarche has no adverse effects on the onset and progression of gonadarche in final height. Both extra- and intraadrenal factors regulate adrenal androgen secretion. Recent studies have shown that premature adrenarche in childhood may have consequences such as functional ovarian hyperandrogenism, polycystic ovarian syndrome, and insulin resistance in later life, sometimes already recognizable in childhood or adolescence. Premature adrenarche may thus be a forerunner of syndrome X in some children. The association of these endocrine-metabolic abnormalities with reduced fetal growth and their genetic basis remain to be elucidated.

Idiopathic short stature: definition, epidemiology, and diagnostic evaluation.

Idiopathic short stature is a condition in which the height of the individual is more than 2 SD below the corresponding mean height for a given age, sex and population, in whom no identifiable disorder is present. It can be subcategorized into familial and non-familial ISS, and according to pubertal delay. It should be differentiated from dysmorphic syndromes, skeletal dysplasias, short stature secondary to a small birth size (small for gestational age, SGA), and systemic and endocrine diseases. ISS is the diagnostic group that remains after excluding known conditions in short children.

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.

Normal genes for the cholesterol side chain cleavage enzyme, P450scc, in congenital lipoid adrenal hyperplasia.

Congenital lipoid adrenal hyperplasia is the most severe form of congenital adrenal hyperplasia. Affected individuals can synthesize no steroid hormones, and hence are all phenotypic females with a severe salt-losing syndrome that is fatal if not treated in early infancy. All previous studies have suggested that the disorder is in the cholesterol side chain cleavage enzyme (P450scc), which converts cholesterol to pregnenolone. A newborn patient was diagnosed by the lack of significant concentrations of adrenal or gonadal steroids either before or after stimulation with corticotropin (ACTH) or gonadotropin (hCG). The P450scc gene in this patient and in a previously described patient were grossly intact, as evidenced by Southern blotting patterns. Enzymatic (polymerase chain reaction) amplification and sequencing of the coding regions of their P450scc genes showed these were identical to the previously cloned human P450scc cDNA and gene sequences. Undetected compound heterozygosity was ruled out in the new patient by sequencing P450scc cDNA enzymatically amplified from gonadal RNA. Northern blots of gonadal RNA from this patient contained normal sized mRNAs for P450scc and also for adrenodoxin reductase, adrenodoxin, sterol carrier protein 2, endozepine, and GRP-78 (the precursor to steroidogenesis activator peptide). These studies show that lipoid CAH is not caused by lesions in the P450scc gene, and suggest that another unidentified factor is required for the conversion of cholesterol to pregnenolone, and is disordered in congenital lipoid adrenal hyperplasia.

Efficacy and safety of a new ready-to-use recombinant human growth hormone solution.

We report 24-month interim results of two multicenter phase III studies in previously untreated children with growth failure secondary to GH deficiency (GHD) that were paramount to the development of a new recombinant human GH (rh- GH, somatropin), approved as the first 'biosimilar' in Europe. Study 1 consisted of 3 parts performed in 89 children. The objective was to compare efficacy and safety of the lyophilized formulation of the new somatropin [Somatropin Powder (Sandoz)] with a licensed reference rhGH preparation and the liquid formulation of the new somatropin [Somatropin Solution (Sandoz)] and to assess long-term efficacy and safety of this ready-to-use Somatropin Solution. Study 2 was performed in 51 children and designed to demonstrate efficacy and safety of Somatropin Powder and to confirm its low immunogenic potential; rhGH was given sc at a daily dose of 0.03 mg/kg. Primary [body height, height SD score (HSDS), height velocity, and height velocity (HV) SD score (HVSDS)] and secondary [IGF-I and IGF binding protein 3 (IGFBP-3)] efficacy endpoints and safety parameters were assessed regularly. In study 1, all treatments showed comparable increases in growth. The baseline-adjusted difference between Somatropin Powder and the reference rhGH product in mean HV was -0.20 cm/yr (95% confidence interval (CI) [-1.34;0.94]) and in mean HVSDS was 0.76 (95% CI [-0.57;2.10]) after 9 months. These very small differences demonstrate comparable therapeutic efficacy between the two treatments. The results of study 2 were consistent with those seen in study 1. Equivalent therapeutic efficacy and clinical comparability in terms of safety and immunogenicity between Somatropin Powder and the reference rhGH product and between Somatropin Powder and Somatropin Solution was demonstrated. The safety and immunogenicity profiles were similar and as expected from experience with rhGH preparations.

GH safety workshop position paper: a critical appraisal of recombinant human GH therapy in children and adults.

Recombinant human GH (rhGH) has been in use for 30 years, and over that time its safety and efficacy in children and adults has been subject to considerable scrutiny. In 2001, a statement from the GH Research Society (GRS) concluded that 'for approved indications, GH is safe'; however, the statement highlighted a number of areas for on-going surveillance of long-term safety, including cancer risk, impact on glucose homeostasis, and use of high dose pharmacological rhGH treatment. Over the intervening years, there have been a number of publications addressing the safety of rhGH with regard to mortality, cancer and cardiovascular risk, and the need for long-term surveillance of the increasing number of adults who were treated with rhGH in childhood. Against this backdrop of interest in safety, the European Society of Paediatric Endocrinology (ESPE), the GRS, and the Pediatric Endocrine Society (PES) convened a meeting to reappraise the safety of rhGH. The ouput of the meeting is a concise position statement.

The Second International Symposium on the Developmental Aspects of Androgen Excess, Toronto, Canada, 20 June 2000.

Clinical hyperandrogenism, in particular polycystic ovary syndrome (PCOS), affects 4-7% of women of reproductive age, making it one of the most common human reproductive endocrinological abnormalities. However, our understanding of the developmental aspects of these disorders remains limited. The Second International Symposium on the Developmental Aspects of Androgen Excess (Toronto, Canada, 20 June 2000) was held with the purpose of fostering greater investigative communication, consensus and focus. It was felt that a better understanding of PCOS phenotypes was needed; that an aggressive attempt should be made to continue to expand the molecular genetic studies of the disorder; that research into the role and mechanism(s) underlying the associated defects in insulin action and signaling should be continued; that longitudinal studies, particularly those focusing on the role of intrauterine stress and malnutrition, and premature adrenarche, on the development of PCOS were warranted; and that an improved understanding of the molecular defects in steroidogenesis present in PCOS is needed.

Management of cryptorchidism.

The forces guiding testicular descent have not been completely elucidated. Both testosterone and anti-Müllerian hormone might play a role. Available evidence suggests that malfunction of the testes of some sort usually precedes maldescent. The proper management of cryptorchidism has long been a controversial issue. In unilateral cryptorchidism, hormonal function and fertility are generally normal. To maximize fertility in patients with bilateral cryptorchidism, surgical treatment should be completed ideally by the first birthday. GnRH is unlikely to be of much help in initiating testicular descent. Cryptorchidism is associated with a three- to tenfold increase in testicular cancer. Twenty percent of tumors in unilateral cryptorchidism are in the normally descended testes. The condition of all boys and men with a history of cryptorchidism should be followed by physicians their entire lives, and these boys and men must become proficient in self-examination.

Twenty-four-hour cortisol profiles demonstrate exaggerated nocturnal rise in diabetic children.

Plasma cortisol was measured every 20 min for 24 h in 12 normal and 8 insulin-dependent, nonketotic, diabetic children treated with one daily injection of insulin. Plasma glucose was also measured every 20 min in the diabetic children. The diurnal pattern of cortisol secretion was identical. The mean 24-h plasma cortisol was similar in both groups, but significantly elevated in the diabetic children between 0200 and 0920 h. Peak cortisol levels were higher in the diabetic than in the normal children. No correlation was found between average plasma glucose and average plasma cortisol, or between the nocturnal change in plasma glucose and average nocturnal plasma cortisol in the diabetic subjects. These studies demonstrate an exaggeration of the normal nocturnal rise in plasma cortisol in diabetic children not related to the levels of plasma glucose.

6 beta-Hydroxycortisol: a noninvasive indicator of enzyme induction.

We measured urinary 6 beta-hydroxycortisol (6 beta OHF) excretion in normal children and in children receiving anticonvulsant therapy with phenobarbital or diphenylhydantoin, 6 beta OHF excretion increased 4- to 7-fold during anticonvulsant therapy. The marked increase in the ratios of 5 beta OHF to 17-hydroxycorticosteroid and 6 beta OHF to free cortisol suggests that the measured increase in urinary 6 beta OHF may serve as an index of induction of the microsomal mixed function oxidase system. This noninvasive approach allows rapid assessment of the effects of drugs and foreign compounds on microsomal hydroxylation of cortisol. This convenient probe can be applied, with particular ease, to further studies in children in whom characterization of the effects of drugs and xenobiotic compounds on hepatic hydroxylation is of interest.

Cytochrome P450IIE1 is elevated in lymphocytes from poorly controlled insulin-dependent diabetics.

Cytochrome P450IIE1, a member of the cytochrome P450 supergene family, was measured in peripheral lymphocytes of 14 patients with insulin-dependent diabetes mellitus who were in poor metabolic control, as evidenced by elevated hemoglobin A1 levels (mean, 11.9 +/- 2.8%; normal, less than 7.8). Only one major form (mol wt, 48,000 daltons) of cytochrome P450IIE1 was detected with a specific polyclonal antibody against P450IIE1. Levels of cytochrome P450IIE1 were very low to undetectable in human lymphocytes from seven normal subjects. However, levels of P450IIE1 were elevated in lymphocytes from patients with insulin-dependent diabetes mellitus. Elevated levels of cytochrome P450IIE1 determined by immunoblot analysis correlate positively with the levels of hemoglobin A1 (r = 0.8), a metabolic indicator in diabetic subjects. In one study subject in whom diabetic control was improved, the drop in hemoglobin A1C levels was accompanied by normalization of P450IIE1 levels.

Fasting glucose insulin ratio: a useful measure of insulin resistance in girls with premature adrenarche.

The purpose of this study was to determine whether the fasting glucose/insulin ratio is a useful screening test for insulin resistance in prepubertal girls with premature adrenarche. The glucose/insulin ratio was compared with the insulin sensitivity index calculated from the frequently sampled iv glucose tolerance test with tolbutamide using the minimal model computer program. Thirty-three prepubertal girls (22 Caribbean Hispanic and 11 African American; mean age, 6.8 yr; bone age, 8 yr) were studied. All underwent a 60-min ACTH stimulation test. The fasting glucose/insulin ratio was also compared with IGF-binding protein-1 and ACTH-stimulated androgen levels. Insulin sensitivity correlated significantly with the glucose/insulin ratio (0.76; P < 0.001), fasting insulin (0.75; P < 0.001), and IGF-binding protein-1 (0.59; P < 0.005). Stepwise regression analysis with the insulin sensitivity index as the dependent variable showed that the fasting glucose/insulin ratio was significantly predictive of the insulin sensitivity index (P < 0.002). When viewed as a screening test, setting a value of the fasting glucose/insulin ratio of less than 7 as abnormal and of less than 5.7 x 10(-4) min/microU.ml for the insulin sensitivity index as evidence of insulin resistance (normal prepubertal insulin sensitivity index, >5.7 x 10(-4) min/microU.ml), the sensitivity of the fasting glucose/insulin ratio was 87%, and the specificity was 89%. Furthermore, those girls with a low glucose/insulin ratio (<7) had higher body mass index, fasting insulin, free T, and ACTH-stimulated 17-hydroxypregnenolone and lower fasting IGF-binding protein-1 and SHBG than those girls with a glucose/insulin ratio greater than 7. The fasting glucose/insulin ratio is a useful screening test for insulin resistance in prepubertal Caribbean Hispanic and African American girls with premature adrenarche.

Depressed excretion of 6 beta-hydroxycortisol in lead-toxic children.

6 beta-Hydroxycortisol (6 beta OHF) is a highly polar metabolite of cortisol, probably formed in the endoplasmic reticulum of hepatocytes by cytochrome P-450-dependent microsomal monoxygenases. Lead decreases the activity of cytochrome P-450-dependent microsomal hydroxylases in vivo and in vitro. To examine possible inhibitory effects of lead on 6 beta OHF metabolism, urinary 6 beta OHF excretion was measured in 26 children with mild to moderate increases in blood lead concentrations. Children were divided into 2 groups on the basis of their response to the EDTA provocative test. This test was used to assess the size of chelatable and potentially toxic lead stores in such children. Children with elevated urinary lead excretion after an EDTA provocative test, i.e. elevated tissue lead stores, had markedly decreased urinary excretion of 6 beta OHF (178 +/- 15 micrograms/m2 X 24 h) compared to children who had negative tests (333 +/- 40 micrograms/m2 X 24 h; P less than 0.01); their urinary cortisol excretion was not different from that of age-matched controls. These findings suggest that lead, at relatively low concentrations, may interfere with hepatic microsomal formation of a cortisol metabolite.

Changes in drug metabolism in children with thyroid disorders.

The rate of disappearance of antipyrine from the plasma is a useful indicator for the in vivo capacity of mixed function oxidation. The half-life of antipyrine was measured before and after treatment in three hypothyroid and three hyperthyroid children, aged three months to 14 years, in order to examine the effect on drug metabolism of thyroid disorders in children. The half-life of antipyrine decreased in all three hypothyroid subjects and increased in all three hyperthyroid subjects after treatment. The mean half-life decreased from 34.5 h to 8.6 h after treatment of the hypothyroid subjects and increased from 6.1 to 10.1 h after treatment of the hyperthyroid subjects. The mean metabolic clearance rate of antipyrine increased from 11.7 to 25 ml/h in the hyothyroid patients while in the hyperthyroid children there was a decrease from 43 to 25 ml/h. The apparent volume of distribution did not change significantly in the treatment, thus changes in the half-life of antipyrine were most likely attributable to alterations in the metabolic clearance rate of antipyrine.