Time Course of the Serum Gonadotropin Surge, Inhibins, and Anti-Müllerian Hormone in Normal Newborn Males During the First Month of Life

Context: Newborns with ambiguous genitalia or males with nonpalpable gonads usually require an early assessment of the presence and functional state of testicular tissue.

Objective: Our objective was to characterize the precise ontogeny of the serum patterns of gonadotropins, testosterone, anti-Müllerian hormone (AMH), and inhibins in normal newborn boys.

Design: We conducted a cross-sectional and longitudinal study.

Subjects: Serum samples were obtained in 57 boys and 13 girls on d 2 of life. A second sample was obtained on d 7, 10, 15, 20, and 30 (boys) and on d 30 (girls).

Main Outcome Measures: Serum levels of gonadotropins, testosterone, AMH, and inhibins were measured.

Results: In males, LH and FSH were undetectable or very low on d 2. By d 7, LH increased to 3.94 +/- 3.19 IU/liter (mean +/- sd) and FSH to 2.04 +/- 1.67 IU/liter. LH/FSH ratios were 0.40 +/- 0.11 (d 2) and 2.02 +/- 0.20 (d 30). AMH rose from 371 +/- 168 pmol/liter (d 2) to 699 +/- 245 pmol/liter (d 30), and inhibin B rose from 214 +/- 86 ng/liter (d 2) to 361 +/- 93 ng/liter (d 30). The inhibin alpha-subunit precursor (pro-alphaC) remained stable during the first month of life. Testosterone levels were 66 +/- 42 ng/dl (d 2), 82 +/- 24 ng/dl (d 20), and 210 +/- 130 ng/dl (d 30). A sexual dimorphism was observed in AMH and inhibin B (lower in girls on d 2 and 30), in LH/FSH ratio (lower in girls on d 30) and in testosterone (lower in girls on d 30).

Conclusions: Sertoli cell markers AMH and inhibin B are the earliest useful markers indicating the existence of normal testicular tissue.