When a couple experiences infertility, both partners may be tested for testosterone levels. Find out what the results of this test means for both males and females.
The Testosterone Test
In both men and women, testosterone levels are an important factor in fertility. Both male infertility testing and female infertility testing may include a test of total testosterone.
The testosterone test is a blood test, requiring a standard blood sample to be taken from the arm. Testosterone levels vary naturally throughout the day, following a circadian rhythm, so the time of the sample should be noted. The normal range for testosterone is very wide in both men and women, so interpretation of the test results may be challenging.
Total, Free, and Bioavailable Testosterone
Testosterone in the blood may be "free" (that is, not bound to any protein), bound to the blood protein albumin, or bound to Sex Hormone Binding Globulin (SHBG), another protein in the blood. The bond between testosterone and albumin is weak, so albumin-bound hormone is easily available to the body's cells. SHBG, on the other hand, binds tightly to the hormone so that it is not available to the body's cells; in other words, it inhibits the action of the hormone.
The term "bioavailable testosterone" (BAT) is the total free testosterone plus albumin-bound testosterone. It is the same as total testosterone minus SHBG-bound testosterone. For diagnostic purposes, BAT is considered a better measure of testosterone than total testosterone.
Adequate testosterone is absolutely critical for normal sperm production. A testosterone test primarily looks for a lower than normal level of testosterone. Testosterone in men is produced in greatest quantities in the testes.
Low testosterone may be caused by an underlying hormonal problem such as a pituitary problem; a disease affecting the testes; or physical damage to the testes. Damage may be caused by physical injury, history of mumps, or chronic alcohol abuse.
Women have much lower levels of testosterone than men. Testosterone has an indirect impact on female fertility, and female testosterone level can be a marker for certain conditions that can cause female infertility.
Low testosterone in women can cause reduced sex drive and decreased energy. High testosterone is much more significant when searching for the cause of infertility. High testosterone may be caused by low estrogen or by ovarian cancer. Polycystic ovarian syndrome (PCOS) is another possible cause. The cause of PCOS is unknown, but increased androgen (male hormone) levels are a primary symptom. Another symptom is anovulation (not producing mature egg cells), which leads to infertility. High testosterone does not cause the infertility, but goes together with it in PCOS.