Testosterone is produced in men by the Leydig cells of the testes. Minute amounts also are secreted by the adrenal glands in men and women and by the ovaries in women. In the male fetus, testosterone is secreted by the genital ridges and fetal testes.

Testosterone is produced in response to stimulation by luteinizing hormone, which is secreted by the adenohypophysis in response to stimulation by gonadotropin-releasing hormone. Testosterone promotes development of the male sex organs and testicular descent in the fetus, induces and maintains secondary sexual characteristics in men, promotes protein anabolism and bone growth, and enhances sodium and water retention to some degree.

• Testosterone levels vary diurnally, with highest levels occurring in the early morning.
• Administration of testosterone, thyroid and growth hormones, clomiphene, and barbiturates may lead to elevated levels.
• Therapy with estrogens and spironolactone (Aldactone) may produce decreased levels.

• In men, support for diagnosing precocious puberty, testicular tumors, and benign prostatic hypertrophy, as indicated by elevated levels
• In women, support for diagnosing adrenogenital syndrome, adrenal tumors or hyperplasia, Stein-Leventhal syndrome, ovarian tumors or hyperplasia, and luteomas of pregnancy, as indicated by elevated levels
• In men and women, support for diagnosing nonendocrine tumors that produce ACTH ectopically, as indicated by elevated levels without diurnal variation
• In men, support for diagnosing infertility, with testicular failure indicated by decreased levels
• Support for diagnosing other disorders associated with decreased testosterone levels (e.g., hypopituitarism, Klinefelter's syndrome, cryptorchidism [failure of testicular descent], and cirrhosis)

Nursing Care Before the Procedure

Client preparation is the same as that for any study involving the collection of a peripheral blood sample (see Appendix I).

• It is recommended that drugs that may alter testosterone levels be withheld for 12 to 24 hours before the test, although this practice should be confirmed with the person ordering the study.

A venipuncture is performed and the sample collected in either a red- or a green-topped tube, depending on the laboratory performing the test. The sample should be handled gently to avoid hemolysis and transported promptly to the laboratory.

Nursing Care After the Procedure

Care and assessment after the procedure are the same as for any study involving the collection of a peripheral blood sample.

• Resume any medications withheld before the test.
• Complications and precautions: Assess increased or decreased levels in relation to age, gender, menstrual or menopausal status, as well as possible sexual dysfunction and medicolegal aspects of the abuse of anabolic steroids related to athletic ability.