Progesterone blood test, serum progesterone
This test measures the level of a hormone called progesterone in your blood.
Your ovaries produce progesterone after ovulation. The most important role of progesterone is to prepare your uterus so that it can receive, implant, and support a fertilized egg during pregnancy.
Progesterone levels are usually low during the first stage, called the follicular stage, of your menstrual cycle. Ovulation is called the luteal stage, when the egg is released into the fallopian tube. After ovulation, progesterone levels go up for about five days before going back down. If pregnancy occurs, your progesterone levels will slowly rise from the ninth week of pregnancy until the 32nd week. The placenta will begin to make progesterone after 12 weeks to help your pregnancy stay healthy.
Because progesterone levels change according to the stage of your menstrual cycle and the stage of your pregnancy, this blood test may be repeated many times.
If you are having trouble getting pregnant, you may have a progesterone blood test as part of a fertility study. A progesterone blood test is the best sign of ovulation. If you are pregnant, you may have this test to check the health of your pregnancy.
You may have this test to find out if:
You are ovulating
Your ovaries are working the way they should
Your pregnancy is at risk
Your doctor may order other blood tests as part of a fertility study. Your doctor may also order an ultrasound to measure the thickness of your endometrium, or the lining inside your uterus.
If you are pregnant, your doctor may order a blood test to measure a hormone called human chorionic gonadotropin, or hCG, to help figure out if your pregnancy is at risk.
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.
Progesterone is measured in nanograms per milliliter (ng/mL). Normal levels are:
0.1 to 0.3 ng/mL for prepubescent girls
0.1 to 0.7 ng/mL in the follicular stage of the menstrual cycle
2 to 25 ng/mL in the luteal stage of the menstrual cycle
10 to 44 ng/mL during the first trimester of pregnancy
19.5 to 82.5 ng/mL during the second trimester of pregnancy
65 to 290 ng/mL during the third trimester of pregnancy
Other conditions can cause abnormal results of a progesterone blood test. For example:
Increased progesterone during pregnancy can mean that you have twins or an abnormal type of pregnancy called a molar pregnancy.
Increased progesterone when you are not pregnant could mean you have a type of ovarian tumor called a lipid ovarian tumor, or chorionepithelioma.
Decreased progesterone during pregnancy could mean that you have a risk for spontaneous abortion, or miscarriage.
Decreased progesterone when you aren't pregnant could mean that you don't have enough female hormones, a condition called hypogonadism.
The test requires a blood sample, which is drawn through a needle from a vein in your arm.
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
Certain medications, such as oral contraceptive pills or steroids, may affect your results.
You don't need to prepare for this test. Let your doctor know the date of your last menstrual period and be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.