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In recent years, it became evident that the hypothalamo-pituitary-gonadal axis is functioning in boys already between the neonatal period and the onset of puberty. With sensitive techniques, testosterone and gonadotropines have been detected in the plasma and urine of prepubertal boys. It is now believed that, during this period of life, the axis is active, but that either the feedback mechanisms are adjusted to a different level, the hypothalamic centers being more sensitive to androgens and keeping the testicular androgen production low, or that the gonads are more refractory to the effect of gonadotropins.

The androgen levels in biological fluids from normal prepubertal boys are extremely low. It is therefore impossible to distinguish the basal values of children with defective steroid production from those of normal children. Recently, several investigators have, however, shown that stimulation of the testicular interstitial cells is possible, if human chorionic gonadotropin is administered for several

Abstract

The frequency of hypoglycemia in 165 children with primary adrenal insufficiency, 118 of whom had Congenital Adrenal Hyperplasia and 47 Addison's Disease, was 18 %. Half of the hypoglycemic episodes occurred in the neonatal period. Hypoglycemia was isolated in 13 children, revealing the disease in 4 newborns with Congenital Adrenal Hypoplasia and in a boy with 11 B Hydroxylase deficiency.

Basal plasma cortisol levels were significantly lower in those of subjects who experienced hypoglycemia ( 47.1 ± 28.6 ng/ml vs. 106.0 ± 86.6 ng/ml, p< 0.001). A significant correlation ( p < 0.001) was found between the plasma concentration of glucose and cortisol at time of hypoglycemia.

Yoshibayashi M, Kamiya T. Saito Y. Nakao K, Nishioka K, Temma S, Itoh H, Shirakami G, Matsuo H. Plasma brain natriuretic peptide concentrations in healthy children from birth to adolescence: marked and rapid increase after birth. Eur J Endocrinol 1995;133:207–9. ISSN 0804–4643

The aim of the present study is to establish the normal range and to determine the developmental changes of plasma brain natriuretic peptide (BNP) concentrations in children. We measured plasma BNP concentrations as well as atrial natriuretic peptide (ANP) concentrations in 58 healthy children from birth to adolescence and in the umbilical vein of 20 healthy neonates using highly sensitive immunoradiometric assays. The plasma BNP concentration was the highest at 0 days of age and descended through maturation to be almost constant and to be at the adult level at 3 months of age. The plasma BNP concentration at 0 days of age (56.7 ± 49.6 fmol/ml; mean±sd) was 25 to 30 times higher than the adult level and 21 times higher than that in the umbilical vein (2.7 ± 1.4fmol/ml), The plasma ANP concentration at 0 days of age was not significantly different from that in the umbilical vein. The ratio of BNP to ANP was also the highest at 0 days of age (1.39 ± 0.72) and decreased through maturation to be at the adult level at 3 months of age. Thus, the plasma BNP concentration in healthy subjects showed a marked, rapid and preferential increase immediately after birth, suggesting that BNP has a physiological role distinct from that of ANP in the perinatal circulatory changes from fetus to neonate.

Muneo Yoshibayashi, Department of Pediatrics, National Cardiovascular Center, 5-7-1 Fujishirodai, Suita, Osaka 565, Japan

Abstract.

Serum somatomedin A (SMA) has been determined in healthy children (n = 188) in relation to age using both a radioimmunoassay and a radioreceptor assay. The SMA levels, only 50% of adult values at birth, rise gradually with age and reach adult levels at 10 years of age. There is a significant correlation (r = 0.46, P < 0.001) between SMA determined by the two methods throughout childhood except during puberty. Immunoreactive SMA shows a marked pubertal rise in values with a peak 2 years earlier for girls than boys, which is not observed by the radioreceptor assay technique. In boys with delayed puberty the increase in immunoreactive SMA is seen first when the testes reach a size of 5 ml. Children with growth hormone deficiency (n = 30) had significantly lower levels of SMA than healthy age-matched controls. Immunoreactive SMA gives a better separation of these groups than the values obtained by radioreceptor assay.

Abstract.

Serum thyrotrophin (TSH), thyroxine (T₄), triiodothyronine (T₃), thyroxine-binding globulin (TBG) and reverse T₃ (rT₃) were measured by radioimmunoassay in 175 girls and 187 boys aged 6.0 to 16.9 years, who were clinically healthy, and had negative serum antithyroglobulin and antimicrosomal antibodies. All the children had normal weight and height and were grouped at 12 months' intervals. In girls, TSH levels ranged between 5.3 ± 0.4 and 6.9 ± 0.5 μU/ml without significant changes with age; serum T₄ decreased up to 13.9 years and rose afterwards; serum TBG was constant up to 13.9 years, decreased subsequently and rose after 15.9 years; serum T₃ levels were lower after 13.0 years than previously; serum rT₃ decreased between 11.0 and 11.9 years and rose thereafter; the calculated serum free T₄ (FT₄) and free T₃ (FT₃) concentrations had a significant rise from 14.0 to 15.9 years followed by a sharp decline; T₃:T₄, rT₃:T₃ and rT₃:T₄ ratios were constant up to 11.9 years, then a rise was seen in T₃:T₄ and a fall in the later ratios, followed by a drop in T₃:T₄ ratio and a sustained rise in rT₃:T₃ and rT₃:T₄ ratios. In boys, TSH levels were constant between 5.2 ± 0.4 and 6.6 ± 0.4 μU/ml; serum T₄ decreased with increasing age; serum TBG was constant up to 13.9 years, and had a sustained fall thereafter; serum T₃ was constant over the age range studied; serum rT₃ levels decreased up to 13.9 years and rose thereafter; FT₄ had no changes with increasing age while FT₃, although constant up to 13.9 years, had a sustained rise afterwards; T₃:T₄ ratio did not change with age, while rT₃:T₃ and rT₃:T₄ ratios, although constant up to 13.9 years, showed a tendency toward a sustained rise thereafter. These sex-different variations in serum thyroid hormone concentrations might be related to the fact that girls mature at an earlier chronological age than boys and may represent a partial response of the body to the qualitatively and quantitatively different energy needs in girls as compared with boys, consecutive to the differences in body composition first appearing at puberty.

Abstract.

Anti-thyroid antibodies are frequently found in otherwise normal populations (4.5–25.8%); however, there is scanty information about thyroid function status in affected individuals. In this report, the serum concentrations of TSH, T₃, T₄, rT₃ and TBG and the titre of anti-thyroglobulin and anti-microsomal antibodies (haemagglutination technique) were studied in 520 healthy school children (260 boys and 260 girls) aged 6.0–17.9 years. Titres equal or greater than 1:16 of one or both antibodies were detected in 58 boys and in 77 girls (in 33 boys and in 24 girls with, and in 25 boys and 43 girls without, associated abnormalities in the serum concentrations of one or several hormones). The age distribution of thyroid antibodies followed a trimodal pattern with peaks at 7, 11 and 16–17 years in both sexes. The most striking finding was an abnormally elevated T₃ concentration in 22 boys and 5 girls with positive antibodies, with no symptoms of thyroid dysfunction and with no clear relationship with simultaneous abnormalities in TSH, T₄ or rT₃; however, in 5 boys the TBG serum levels were increased. Serum from these patients was incubated with [¹²⁵I]T₃ before free radioactivity was precipitated with dextran-coated charcoal and the aliquots were analyzed by paper electrophoresis. Serum samples with high T₃ levels bound significantly more radioactivity than normal or T₃-free serum (P < 0.001) and an abnormal peak of radioactivity was present in the gamma globulin fraction, in the former but not in the latter two types of sera. The presence of high serum T₃ levels in the absence of clinical symptoms of hyperthyroidism was probably due to sequestration of T₃ by the anti-thyroglobulin antibody, which may have cross-reactivity with T₃ and T₄, as has previously been demonstrated both in animals and humans.