Serum Concentrations of Inhibin B in Healthy Females and Males Throughout Life.

OBJECTIVE

To describe the natural history of inhibin B throughout life according to sex, age, and pubertal development.

METHODS

Based on serum samples from 2707 healthy controls aged 0 to 80 years, sex- and age-specific reference ranges of inhibin B concentrations were constructed. Concentrations were evaluated according to pubertal development and use of oral contraceptives (OCs). Also, measurements from 42 patients with Klinefelter syndrome were included.

RESULTS

In both sexes, inhibin B concentrations were high during minipuberty, decreased in childhood, and significantly increased from Tanner stages B1 to B3 (peak: B4) in females and from G1 to G3 (peak: G3) in males. Despite variations in menstruating females, inhibin B concentrations remained relatively constant after puberty until becoming unmeasurable at menopause. Despite a modest decrease, the inhibin B concentration in males remained relatively high from puberty onward. At any age, males had highest concentrations. Inhibin B SD scores were lower in OC users (median SD score = -0.88) than in nonusers (SD score = 0.35), P < .001. In patients with Klinefelter syndrome, inhibin B concentrations spanned the reference range until approximately 15 years of age, where they decreased to subnormal or unmeasurable levels.

CONCLUSION

Valuable sex- and age-specific reference data for inhibin B concentrations were provided. In OC users, decreased concentrations of inhibin B underlined the ovaries as the only place of inhibin B production. In patients with Klinefelter syndrome, the decline in inhibin B concentrations at puberty underlined the shift in regulation of inhibin B production at pubertal onset.