Testosterone Total

Testosterone is the principal androgenic steroid hormone. In males, testosterone is secreted primarily by Leydig cells of the testes under the regulation of luteinizing hormone (LH). In circulation, the majority of testosterone is bound to sex hormone–binding globulin (SHBG), with a smaller fraction bound to albumin and a minor proportion present in the free, biologically active state.

Decreased total testosterone concentrations in males may be associated with hypogonadism, hypopituitarism, hyperprolactinemia, renal failure, hepatic cirrhosis, or Klinefelter syndrome. Elevated total testosterone concentrations in males may result from adrenal or testicular tumors, congenital adrenal hyperplasia, or disorders of the hypothalamic–pituitary–testicular axis.

In females, testosterone is produced by the ovaries, adrenal glands, and peripheral tissues, and circulates at concentrations approximately tenfold lower than those observed in males. As in males, testosterone in females is largely bound to SHBG and albumin, with a small free fraction. Increased total testosterone levels in females may be observed in polycystic ovary syndrome (PCOS), stromal hyperthecosis, ovarian or adrenal tumors, congenital adrenal hyperplasia, and other disorders of the hypothalamic–pituitary–ovarian axis. Clinical manifestations of androgen excess in females may include infertility, amenorrhea, obesity, and hirsutism.

Store/transport at 15–30°C for ≤8 hours; 2–8°C for ≤48 hours; freeze at ≤ –20°C if delayed. Avoid repeated freeze–thaw cycles.

Hemolyzed or unseparated specimens.

Enhanced Chemiluminescence

• Wilson JD, Foster DW. Williams Textbook of Endocrinology. 8th ed. Philadelphia, PA: W.B. Saunders; 1992:822–832.
• Burtis CA, Ashwood ER. Tietz Fundamentals of Clinical Chemistry. 4th ed. Philadelphia, PA: W.B. Saunders; 1996:671–672.
• Cowan BD, Seifer DB. Clinical Reproductive Medicine. Philadelphia, PA: Lippincott-Raven; 98–100.

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