Replacement therapy: arginine vasopressin (AVP), growth hormone (GH), cortisol, thyroxine, testosterone and estrogen

Replacement therapy is routinely used to treat hormone deficiencies of patients who have had surgery or radiation therapy that damages the hypothalamus or pituitary gland. Hormones commonly replaced include: arginine vasopressin (AVP), growth hormone (GH), cortisol, thyroxine (T4), testosterone and estrogen. AVP, synthesized in the hypothalamus, is stored in and released by the posterior lobe of the pituitary gland. GH is synthesized and released by the anterior pituitary gland. The other hormones are produced and released by target glands each of which is stimulated by a specific anterior pituitary hormone, which in turn is controlled by release of a specific hypothalamic hormone. Feedback control by a high circulating concentration of the target gland's hormone regulates hypothalamic hormone release. Deficiency of AVP, important for water balance in the body, is restored with the synthetic analogue, 1-desamino-8-D-arginine vasopressin (DDAVP); it is given as a nasal spray or by injection. GH is required for normal growth in the developing child; recombinant GH, produced in bacteria, is injected subcutaneously. Adrenocorticotropic hormone (ACTH) controls release of cortisol which is produced by the adrenal cortex and enables the body to cope with stress; cortisol is replaced with prednisolone given orally. Thyroid stimulating hormone (TSH) controls release of the thyroid hormones, T4 and triiodothyronine (T3), which promote growth and development, and regulate energy metabolism; for replacement of T4, oral synthetic L-thyroxine is given. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) control release of testosterone, which promotes maturation of sperm and development of male sexual characteristics; replacement testosterone is administered intramuscularly. In females, FSH and LH control release of estrogens and progesterone which prepare the reproductive tract for release of the ovum, fertilization, implantation and development of the embryo, replacement by estrogen and progesterone preparations which are orally effective is given in a cyclic manner. A transdermal delivery system is available. Nursing implications include cautions and contraindications, potential problems of over-replacement, drug interactions as well as patient teaching points.