Progesterone, a hormone produced by the ovaries, is primarily involved in the preparation of the uterus for pregnancy and its maintenance during pregnancy. The placenta begins producing progesterone at 12 weeks of gestation. Progesterone level peaks in the midluteal phase of the menstrual cycle. In nonpregnant women, progesterone is produced by the corpus luteum. Progesterone is the single best test to determine whether ovulation has occurred.

This test is part of a fertility study to confirm ovulation, evaluate corpus luteum function, and assess risk for early spontaneous abortion. Testing of several samples during the cycle is necessary. Ovarian production of progesterone is low during the follicular (first) phase of the menstrual cycle. After ovulation, progesterone levels rise for 4–5 days and then fall. During pregnancy, there is a gradual increase from week 9 to week 32 of gestation, often to 100 times the level in the nonpregnant woman. Levels of progesterone in twin pregnancy are higher than in a single pregnancy. Serum progesterone levels used with β-hCG assist in differentiating normal uterine pregnancy from abnormal uterine or ectopic pregnancy.

Men: <1.0 ng/mL or <3.2 nmol/L

Women:

• Prepubertal: 0.1–0.3 ng/mL or 0.3–1.0 nmol/L

• Follicular: 0.1–0.7 ng/mL or 0.5–2.3 nmol/L

• Luteal: 2–25 ng/mL or 6.4–79.5 nmol/L

• First trimester: 10–44 ng/mL or 32.6–140 nmol/L

• Second trimester: 19.5–82.5 ng/mL or 62.0–262 nmol/L

• Third trimester: 65–290 ng/mL or 206.7–728 nmol/L

1. Obtain a 5-mL venous blood sample (red-topped tube). Serum is needed for test. Observe standard precautions. Label the specimen with the patient’s name, date and time of collection, and test(s) ordered. Place the specimen in a biohazard bag.

2. The test request should include gender, day of last menstrual period, and length of gestation in women.

3. If indicated, a β-hCG may be ordered at the same time.

4. Although urine levels may be tested, serum is preferred.

1. Increased progesterone levels are associated with the following conditions:

   1. Congenital adrenal hyperplasia

   2. Lipoid ovarian tumor

   3. Molar pregnancy

   4. Chorionepithelioma of ovary

   5. Pregnancy

2. Decreased progesterone levels are associated with the following conditions:

   1. Threatened spontaneous miscarriage

   2. Galactorrhea–amenorrhea syndrome (primary or secondary hypogonadism)

   3. Short luteal phase syndrome

   4. Ovarian cancers

   5. Toxemia of pregnancy

Pretest Patient Care

1. Explain test purpose and procedure. Note date of last menstrual period and length of gestation.

2. Do not administer radioisotopes within 1 week before the test.

3. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

1. see Appendix E for drugs that affect test outcomes.

2. Progesterone 5–10 ng/mL or 16–32 nmol/L: pathologic pregnancy

3. Progesterone <5 ng/mL or <16 nmol/L: nonviable pregnancy