Progesterone

What is being tested?
This test measures the level of progesterone in the blood. Progesterone is a hormone whose main role is to help prepare a woman’s body for pregnancy, working together with several other female hormones.
Every month, the hormone oestrogen causes the endometrium (the lining of the uterus) to rebuild and thicken, while a surge of luteinising hormone (LH) causes an egg to be released from one of the two ovaries. The corpus luteum (a yellow mass of cells) then forms at the site where the egg was released and starts producing progesterone. This hormone stops the endometrium from growing and prepares the uterus for the implantation of a fertilised egg.
If fertilisation does not occur, the corpus luteum breaks down, progesterone levels fall and menstrual bleeding begins. If a fertilised egg implants in the uterus, the corpus luteum continues to produce progesterone. After several weeks, the placenta replaces the corpus luteum as the main source of progesterone, producing large amounts for the rest of the pregnancy.

How is the sample collected for testing?
A blood sample is obtained by drawing blood from a vein in the arm (cubital vein).

1. How is it used?
2. When is it requested?
3. What does the result mean?
4. Is there anything else I should know?

1. How is it used?
Because progesterone levels vary predictably throughout the menstrual cycle, repeated measurements over time can be used to help diagnose fertility problems. Progesterone can be measured to determine whether a woman has ovulated (whether an egg has been released from the ovaries), to determine when ovulation occurred and to monitor the success of induced ovulation.
In early pregnancy, measurements of progesterone and human chorionic gonadotrophin (hCG) can be used to help diagnose an ectopic pregnancy or a failing pregnancy (which may end in miscarriage), although these tests do not distinguish between the two conditions. Progesterone levels may be measured during a high-risk pregnancy to help assess the health of the placenta and fetus.
Progesterone levels may be monitored in women who have difficulty carrying a pregnancy to term, as low hormone levels can cause miscarriage. Hormone levels may be monitored regularly in a woman in early pregnancy who is receiving progesterone supplements, to assess the effectiveness of that treatment.
In women who are not pregnant, progesterone levels may be used, together with other tests, to determine the cause of abnormal uterine bleeding.

2. When is it requested?
Progesterone levels are measured:

• as part of an infertility assessment, when a woman is having difficulty becoming pregnant and the doctor wants to check whether she is ovulating normally
• to determine whether and when ovulation has occurred after it has been induced with medication
• when symptoms such as abdominal pain and light dark bleeding (spotting) suggest an ectopic pregnancy or a threatened miscarriage
• to monitor the effectiveness of treatment in a woman who needs progesterone supplements to carry her pregnancy to term
• to monitor the health of the placenta and fetus during a high-risk pregnancy
• when a woman who is not pregnant has had abnormal uterine bleeding

3. What does the test result mean?
To interpret progesterone results, it is necessary to know at what point in her menstrual cycle or pregnancy a woman is. Progesterone levels usually start to rise when an egg is released from the ovary and continue to rise for several days, then either fall again with menstruation or continue to rise with pregnancy.
If progesterone levels do not rise and fall on a monthly basis, a woman may not be ovulating or having periods. If progesterone does not rise normally in the first weeks of pregnancy, there may be a risk of ectopic pregnancy or miscarriage. If progesterone levels do not rise over time, there may be problems with the placenta and the fetus.
Progesterone levels will naturally be higher in a twin pregnancy than in a single pregnancy.
Raised progesterone levels may occasionally occur with luteal ovarian cysts, hydatidiform mole (molar pregnancy) and a rare form of ovarian cancer, or because of overproduction of progesterone by the adrenal glands.
In pregnancy, low progesterone levels may be associated with toxaemia (pre-eclampsia or gestosis).

4. Is there anything else I should know?
Taking oestrogen and progesterone supplements can produce inaccurate results.

1. Is the test performed in men?
2. Are there other uses for progesterone?
3. If I am menopausal and taking hormone replacement therapy (HRT), do I still need my progesterone level monitored?

1. Is the test performed in men?
No. Progesterone has no defined role in men.

2. Are there other uses for progesterone?
Yes. Progesterone (in synthetic form, or progestogens) is often used in hormone replacement therapy (HRT) for menopausal women. Recently, however, on the basis of numerous clinical studies, the use of progestogens combined with oestrogen therapy has become controversial. Progesterone is also used in some contraceptive pills.

3. If I am menopausal and taking hormone replacement therapy (HRT), do I still need my progesterone level monitored?
Sometimes. If you still have your uterus and have certain symptoms, such as uterine bleeding, your doctor may request a progesterone test together with other tests. If you no longer have a uterus (removed during a hysterectomy), HRT will not include progesterone and it will not need to be monitored.