Normal Levels of Testosterone

Testosterone is a hormone produced by the testes in men and by the ovaries and adrenal glands in women. In men, testosterone is involved in sperm production, sex drive, red blood cell production, muscle strength, muscle mass, fat distribution and bone density. In women, testosterone plays a role in sex drive, muscle mass and bone density.

Significance

• In males, a testosterone level is obtained to evaluate early or late puberty in boys and impotence or infertility in men. In women, a testosterone level is used to evaluate irregular menstrual periods, male body characteristics and excessive or abnormal hair growth. A testosterone test may be included in diagnostic testing for ovarian or testicular cancers.

The Test

• A blood sample for a testosterone test is obtained from a vein by a healthcare professional and the sample is sent to a laboratory for processing. Usually, fasting is not required before this hormone level is drawn. Risks associated with a blood draw include excessive bleeding, fainting, feeling light-headed, blood accumulation under the skin and infection at the blood draw site.

Normal Levels

• According to MedlinePlus.com, a normal testosterone level for an adult male is 300 to 1,000 nanograms per deciliter and for an adult female is 20 to 80 nanograms per deciliter. Blood should be drawn in the morning since testosterone is highest at that time. Different laboratories may have different normal testosterone ranges. Your physician will decide if your lab test is abnormal.

Medication Interactions

• Certain medications can increase or decrease testosterone levels in the blood. Medications that may cause an increased testosterone level are oral contraceptives, estrogens, barbiturates and anticonvulsants. Medications that may cause a decreased level of testosterone include spironolactone, phenothiazine, ketoconazole, steroids, alcohol, digoxin, diethylstilbestrol, dexamethasone and androgens.

Increased Levels

• Increased levels of testosterone in men may indicate idiopathic sexual precocity, pinealoma, encephalitis, congenital adrenal hyperplasia, andrenocortical tumor, testicular or extragonadal tumor, hyperthyroidism and testosterone resistance syndromes. Increased levels of testosterone in females may indicate ovarian tumor, adrenal tumor, congenital andrenocortical hyperplasia, trophoblastic tumor, polycystic ovaries and idiopathic hirsutism.

Decreased Levels

• Decreased levels of testosterone in men may indicate Klinefelter's syndrome, cryptorchidism, primary and secondary hypogonadism, Down syndrome, orchidectomy and hepatic cirrhosis. If your testosterone levels are low, your physician will discuss any further testing or treatment options that are indicated for your situation.