Elevation of serum luteinizing hormone levels during hydrocortisone treatment in infant girls with 21-hydroxylase deficiency

During the first months of postnatal life serum luteinizing hormone (LH) levels in girls are lower than in boys. The mechanism of this sex difference is not known. In order to study the possible influence of high levels of androgens and other adrenal steroids on serum gonadotropins during the first months of life, nine girls with salt-losing congenital adrenal hyperplasia (CAH), mean ± SD age 17.1 ± 7.52 days at diagnosis, were studied before and during oral hydrocortisone replacement therapy for 45.7 ± 29.8 days. A control group of 16 girls (C1) and 15 boys (C2), mean ages 41.7 ± 33.6 and 59.3 ± 43.3 days, respectively, was also studied. Serum LH and follicle stimulating hormone (FSH) were determined by enzymoimmunoassay in the presence of one monoclonal and one polyclonal antibody. In treated girls with CAH, mean ± SD serum LH (3.49 ± 82 IU1−1) was significantly higher than in C1 (0.47 ± 0.38) p < 0.02, and similar to C2 (2.52 ± 1.74), while mean ± SD serum FSH (3.72 ± 1.78 IU1−1) was not different from C1 (6.57 ± 5.23). The mean ± SD serum FSH/serum LH ratio (2.53 ± 1.44) was lower than in C1 (14.9 ± 13.6) and similar to C2 (1.60 ± 1.69). These data suggest that high levels of foetal and/or perinatal adrenal steroids, probably androgens, might modulate gonadotropin secretion after the neonatal period. The fact that, after adrenal steroid suppression, serum LH and the serum FSH/serum LH ratio in these infant girls with CAH were similar to that of control boys suggests that foetal or perinatal androgenic steroids have an effect on the control of LH secretion that persists after androgen withdrawal.