Children's Health

Hormone Tests to Check for Undescended Testicles

There are two ways that hormones can help the doctor check a baby or young boy for undescended or absent testicles.

One way is a blood test that checks the levels of certain hormones, including one called Müllerian-inhibiting substance (MIS). The test results can help the doctor tell if the testicles are present and undescended or if they are absent (anorchia).

MIS is produced by the testicles and can be detected in a blood sample from a boy 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 likely absent.

Blood tests may also check the levels of two other hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH). When the testicles are absent, these hormone levels are both higher than normal.

A second way to check for undescended or absent testicles is to get an injection of human chorionic gonadotropin (hCG) hormone for a few days. This hormone stimulates the testicles to release testosterone. The doctor then will check if testosterone levels go up. If both the testicles are absent, testosterone levels will not increase. HCG also stimulates enlargement of the testicles, making it easier to locate the testicle during a physical exam.

Sometimes the results of these tests are not clear. For example, a boy may have normal levels of LH and FSH, but the hCG test does not produce an increase in testosterone. If the results are not clear, the doctor may need to do surgery to find and evaluate the undescended testicles.