[Value of the assay of urinary gonadotropins in pediatric endocrinology]. / Intérêt du dosage des gonadotrophines urinaires en endocrinologie pédiatrique.

An assay for urinary gonadotropins (UG) performed after acetone extraction is presented. This dosage was performed either on a sample of the 24 assay urine, or on the fractionated 12 hr/12 hr urines (night/day) in normal children whose ages ranged from 2 to 20 years and in children presenting with various endocrine diseases (on about 2,000 urine samples). Normal values were established according to sex and stage of puberty. In boys, the lack of overlap between values of LH (UI/24 hr) observed in stage I (prepubescent, 9-13 yrs) and those observed in stage II represents an obvious biological marker of the onset of puberty. The night/day ratio of LH also increases close to puberty, reflecting the onset of the well-known night secretion of LH, at the time of the first stages of puberty. In girls, the preferential increase in FSH is the best criterion for the onset of puberty. In children with endocrine diseases, assay for UG/24 hr is a valuable parameter of the gonadotropic function allowing 1. to separate delayed puberty from hypogonadotropic hypogonadism; 2. to confirm a diagnosis of precocious puberty and 3. to control a treatment with LHRH analogous.

Control of vitamin D metabolism in preterm infants: feto-maternal relationships.

To assess the relationship between maternal and fetal mineral homeostasis, serum calcium, magnesium, inorganic phosphate, parathyroid hormone, and vitamin D metabolite concentrations in venous cord sera from 15 preterm singletons and 3 twin pairs were compared with the levels found in maternal sera. Cord calcium, magnesium, and phosphorus levels were significantly higher than the respective levels in maternal samples. There was a significant relationship between the two compartments for all three analyses. Cord serum 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, and 1,25-dihydroxyvitamin D levels were significantly lower than those observed for the mothers. Association of the cord concentration with that of the mothers was observed only for the first two metabolites. There was no relationship between the maternal 1,25-dihydroxyvitamin D levels and gestational age, calcium, magnesium, inorganic phosphate, or 25-hydroxyvitamin D. Cord 1,25-dihydroxyvitamin D correlated significantly only with cord calcium levels. Immunoreactive parathyroid hormone levels were within normal limits both in cord and maternal samples. Our data suggest that after 31 weeks of gestation: (1) calcium, magnesium, and inorganic phosphate cross the placental barrier against a concentration gradient; (2) the fetus depends on the maternal supply for 25-hydroxyvitamin D and 24,25 dihydroxyvitamin D; (3) the feto-placental unit synthesizes 1,25-dihydroxyvitamin D according to fetal needs.

Hypoparathyroidism during pregnancy: treatment with calcitriol.

A pregnant woman suffering from idiopathic hypoparathyroidism was treated with calcitriol [0.5-2 micrograms/day 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3)]. Her twin infants were delivered by cesarian section at 37 weeks of gestation. Laboratory investigations in the perinatal period disclosed: 1) normal serum calcium and phosphorus levels in the mother, 2) normal babies with no clinical or biochemical signs of hyperparathyroidism, 3) a low serum level of 25-hydroxyvitamin D despite a normal serum level of 1,25-(OH)2D in the mother, and 4) a low level of 25-hydroxyvitamin D and a high level of 1,25-(OH)2D in cord serum in both infants. It is suggested that calcitriol is an effective treatment of hypoparathyroidism during pregnancy and produces no ill effects on the baby.