Inhibin B – laboratory test

Opis produktu

Why inhibin B is tested

Inhibin B is a protein hormone produced in women by the cells of small, developing ovarian follicles, and in men by the Sertoli cells in the testes. The hormone inhibits the secretion of FSH by the pituitary gland. In women, the inhibin B level rises at the beginning of the follicular phase, is low in the luteal phase, and falls to very low values after the menopause. When measured at the beginning of the cycle, it reflects the number of follicles, which is why it is sometimes used as a supplementary measure in assessing ovarian reserve. In men, inhibin B together with FSH is a more sensitive indicator of sperm production than FSH alone. The test is also used in the diagnosis and monitoring of certain ovarian tumours.

When it is worth having this test

• in the diagnosis of infertility in women, as a supplement to the FSH and AMH tests and an ultrasound scan,
• in the diagnosis of male infertility, when the semen analysis is abnormal, together with FSH,
• before a decision on a testicular biopsy or in assessing testicular function, when ordered by a doctor,
• in monitoring the treatment of hypogonadotropic hypogonadism,
• in the diagnosis and monitoring of granulosa cell tumours of the ovary, on a doctor’s order.

How to prepare

• In women, blood is taken in the follicular phase of the cycle, ideally on day 3 of the cycle, or on the day specified by the doctor, because the inhibin B level changes during the cycle.
• Come in the morning, rested after a night’s sleep, and rest for a few minutes before the blood is taken.
• Men can have the test on any day, preferably in the morning.
• Tell your doctor about any hormonal treatment and ovarian stimulation.

How to read the result

The result depends on the day of the cycle, so in women before the menopause it is interpreted with caution. According to ESHRE and ASRM, the basic tests of ovarian reserve are AMH and the antral follicle count on ultrasound, while inhibin B plays a supplementary role. A normal result does not rule out an ovarian tumour. The reference range on the laboratory printout applies.

What to test together

AMH, FSH, LH, Estradiol, Testosterone, Semen analysis. More: Badania-Medyczne.pl.

Sources: ALAB laboratoria, Inhibina B (in Polish; indications, collection timing, turnaround time); Mayo Clinic Laboratories, Inhibin B, Serum (uses, interpretation, variation during the cycle); American Society for Reproductive Medicine, Testing and interpreting measures of ovarian reserve, 2020 (AMH as a marker of reserve, no value as a fertility test); ESHRE, Ovarian stimulation guideline: information for patients, 2025 (AMH and AFC predict the number of eggs, not pregnancy). For information only; it does not replace a medical consultation.