Hormone tests and undescended testicles

A baby or young boy who has undescended testicles on both sides (bilateral) that cannot be felt during a physical exam (nonpalpable) usually has a blood test to measure levels of various hormones. The results can help a health professional decide whether the testicles are present and undescended or absent (anorchia). If the testicles are present, they are likely to be located in the inguinal canal or abdomen.

Müllerian-inhibiting substance (MIS) is a hormone that normally is produced by the testicles and can be detected in a blood sample from a male until he reaches puberty. If a boy who has an undescended testicle has measurable MIS in his blood, it is a good sign that one or both testicles are present. If MIS cannot be detected in the boy's blood, then both testicles are almost certainly absent.

Two other hormones also may be measured: luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These hormone levels are both higher than normal when the testicles are absent.

Human chorionic gonadotropin (hCG) is a hormone that stimulates the testicles to release testosterone. This hormone is sometimes given by injection for a few days to determine whether testosterone levels increase. HCG also stimulates enlargement of the testicles, making it easier to locate the testicle during a physical exam. If both the testicles are absent, testosterone levels will not increase.

Sometimes the results of these tests are not clear. For example, MIS may be detected or the levels of LH and FSH are normal, but the hCG test does not produce an increase in testosterone. In these cases where the results are not clear, surgery may be necessary to locate and evaluate the undescended testicles.