Sex Hormones Tests Health Article

Definition

Sex hormones tests include tests that measure levels of estrogen (estradiol and estriol), progesterone, and testosterone (total and free).

Purpose

In non-pregnant women, a test of estradiol (E2) levels is ordered to evaluate delayed sexual maturity, precocious puberty, menstrual problems, and infertility, and ovarian failure. It is also used to test for tumors in both males and females that secrete estrogen. The test is also used to measure estrogen secretion in males who present with gynecomastia and feminization in male children.

Estriol (E3), another estrogen, is only ordered for pregnant women (typically at 15–18 weeks gestation). The test is used as part of the triple marker screen (in association with alpha fetoprotein and chorionic gonadotropin) for Down syndrome.

A progesterone test is ordered to evaluate women for anovulation, and to investigate precocious puberty. Progesterone may be measured in those persons with ovarian or adrenal cancer that secrete progesterone.

The testosterone test (free testosterone and/or total testosterone) is used to evaluate delayed sexual development, male sexual precocity, testicular failure, virilism in females, infertility, and tumors that secrete testosterone.

Precautions

Both the estrogen and testosterone test are most often measured by radioimmunosasay and results can be affected by radioactive scans. When RIA is used the estradiol or estriol tests should not be performed on a patient who has received radioactive dye within 48 hours prior to the test. For RIA testosterone tests, the period between the scan and the test should be at least seven days. Oral contraceptives may interfere with progesterone and estradiol results. Tetracycline, some phenothiazines, diazepam, clomiphene, and some vitamins may interfere with estradiol results.

Estradiol and progesterone results vary with the phase of the menstrual cycle, and this must be taken into account when interpreting the results of these tests.

Sex hormone tests are performed on blood collected by venipuncture. The nurse or phlebotomist performing the procedure should observe universal precautions for the prevention of transmission of bloodborne pathogens.

Description

The sex hormones control the development of primary and secondary sexual characteristics and regulate the sex-related functions of the body, such as the menstrual cycle, and the production of eggs or sperm. Because of their normally low concentration in plasma the sex hormones are typically measured by radioimmunoassay (RIA), chemiluminescence immunoassay, or fluorescent immunoassay.

Estradiol

While there have been more than 30 of these hormones identified, only estradiol (E2) is necessary to evaluate ovarian function. Estradiol is the most potent of the estrogens, but it accounts for only one-third of the total estrogen in premenopausal females. In the nonpregnant female the ovaries are responsible for almost all estradiol production. In pregnancy, some estradiol is also produced by the placenta. Estradiol is produced from cholesterol, androstenedione, and testosterone. In males, estradiol is mainly produced from testosterone by the testes, but a small amount is also made by the adrenal cortex.

In menopause, the ovaries stop producing estradiol and estrone (E1) becomes the principal estrogen. A small amount of estradiol is formed from adrenal conversion of androstenedione, but this accounts for only about 15% of total estrogens. Plasma estradiol will be low in menopause, and FSH and LH will usually be increased. The measurement of estrone is seldom needed, but may be used to investigate vaginal bleeding after menopause or when estrone secreting ectopic hormone production is suspected.

Prior to menopause, estradiol is most often measured to evaluate amenorrhea and ovarian failure. In primary ovarian failure the ovaries may either fail to develop (as in Turner syndrome) or fail to produce estrogens as a result of autoimmune, metabolic, or endocrine disease. The plasma estradiol will be low, but the plasma levels of both LH and FSH are elevated. If secondary sexual characteristics are undeveloped, and the person is of short stature, chromosomal studies may reveal Turner syndrome as the cause. Primary amenorrhea results in failure to have a menses by age 16. In addition to ovarian failure, primary amenorrhea may be caused by endometriosis, polycystic ovary syndrome, anatomic defects in the vagina or uterus, and other disorders. In secondary ovarian failure, amenorrhea may be caused by pituitary failure or prolactinoma. In the former, both plasma and urinary LH and FSH will be low. In prolactinoma, LH and FSH are low because their release is suppressed by excessive secretion of prolactin which inhibits corticotropin releasing hormone.

An increased plasma level of estrogen indicates ovarian hyperfunction which may occur as a result of an ovarian tumor such as a granulosa-thecal cell tumor or signals the presence of an ectopic estradiol-producing tumor.

Estradiol is also measured to evaluate the response of patients to progesterone challenge and to determine responsiveness to clomiphene. In a person with amenorrhea, estradiol greater than 40 pg/mL following progestin administration excludes estrogen deficiency as a cause of amenorrhea. Clomiphene blocks the hypothalamic response to estrogen and is a treatment for patients with anovulation who have adequate estrogen and normal pituitary function. Use of the drug requires demonstration that the ovaries can produce estradiol.