Serum progesterone is a test to measures the amount of progesterone in the blood. Progesterone is a hormone produced mainly in the ovaries.

In women, progesterone prepares the uterus for pregnancy and the breasts for milk production. After ovulation, progesterone helps make the uterus ready for implantation of a fertilized egg.

Men produce some amount of progesterone, but it probably has no normal function except to help produce other steroid hormones.

See also: Pregnanediol

Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In an infant or young child, the area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

Your health care provider may tell you to stop taking drugs that may affect the test. Drugs that can interfere with the test include progesterone and birth control pills.

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

This test is done to diagnose or rule out disorders associated with abnormal progesterone levels.

Progesterone levels vary depending on when the test is done. Blood progesterone levels start to rise midway through the menstrual cycle, continue to rise for about 6 to 10 days, and then fall if fertilization does not result.

Levels continue to rise in early pregnancy.

This following are normal ranges based upon certain phases of the menstrual cycle and pregnancy:

• Female (pre-ovulation): less than 1 ng/mL
• Female (mid-cycle): 5 to 20 ng/mL
• Male: less than 1 ng/mL
• Postmenopausal: less than 1 ng/mL
• 1st trimester: 11.2-90.0 ng/mL
• 2nd trimester: 25.6-89.4 ng/mL
• 3rd trimester: 48.4-42.5 ng/mL

Note: ng/mL = nanograms per milliliter

Higher-than-normal levels may be due to:

• Pregnancy
• Adrenal cancer
• Ovarian cancer
• Congenital adrenal hyperplasia

Lower-than-normal levels are associated with:

• Amenorrhea
• Fetal death
• Threatened abortion
• Toxemia of pregnancy

Additional conditions under which the test may be performed:

• Ectopic pregnancy
• Infertility

• Excessive bleeding
• Fainting or feeling lightheaded
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)
• Multiple punctures to locate veins

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.