Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (1016 page)

   Also used as an effective marker for Down syndrome pregnancies.

   Inhibin B is produced by granulosa cells of small developing antral follicles.

   Rises to peak in early puberty; constant level thereafter.

   Gradually declines after age 40. In early menopause, follicular-phase inhibin B declines, whereas inhibin A and estradiol are still within normal range.

   May indicate low ovarian reserve in perimenopausal women and transition to menopause; useful for assisted reproduction. Measured on days 3–5 of menstrual cycle.

   After menopause, inhibins A and B fall to very low levels.

   May be useful to screen for preeclampsia.

   As an aid in the diagnosis of patients with granulose cell tumors of the ovary, when used in combination with inhibin B.

   
Males:

   Inhibin B is predominant in males and supports spermatogenesis by negative feedback of FSH.

   Inhibin A is not significant in males (normal values <480 pg/mL); values remain fairly constant.

   May be decreased in male infertility.

   Interpretation