At specific times during a woman’s menstrual cycle (period) to determine whether/when she is ovulating and producing eggs, and sometimes during early pregnancy if symptoms suggest an ectopic or failing pregnancy.
A blood sample taken from a vein in your arm
This test measures the concentration of progesterone in the blood. Progesterone is a hormone whose main role is to help prepare a woman’s body for pregnancy; it works together with several other female hormones.
On a monthly basis, the hormone oestrogen causes the endometrium (the lining of the womb, or uterus) to grow and replenish itself, while a surge in luteinising hormone (LH) leads to the release of an egg from one of the two ovaries. The corpus luteum (a small yellow mass of cells) then forms in the ovary at the site where the egg was released and begins to produce progesterone. This progesterone stops endometrial growth and prepares the uterus for the possible implantation of a fertilised egg. If menstrual cycles are regular and conform to a standard 28 day length, progesterone concentrations will normally peak on approximately day 21 of the cycle (with day 1 being the first day of menstruation).
If fertilisation does not occur, the corpus luteum degenerates, progesterone concentrations fall, and menstrual bleeding begins. If a fertilised egg is implanted 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 relatively large amounts of the hormone throughout the rest of a normal pregnancy.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
How is it used?
Since progesterone concentrations vary predictably throughout the menstrual cycle, multiple measurements can be used to help diagnose infertility problems. Progesterone can be measured to determine whether or not a woman has ovulated (released an egg from the ovary), to determine when ovulation occurred, and to monitor the success of medically induced ovulation.
In early pregnancy, progesterone measurements may sometimes be used, along with human chorionic gonadotropin (hCG) testing, to help diagnose an ectopic pregnancy or failing pregnancy (one leading to miscarriage), although these tests will not differentiate between the two conditions, and hCG is more often used on its’ own for this purpose.
In women who are not pregnant, progesterone concentrations may be used, along with other tests, to help determine the cause of abnormal uterine bleeding.
When is it requested?
Progesterone concentrations may be measured:
- As part of an infertility assessment, when a woman is having trouble getting pregnant and the doctor wants to verify that she is ovulating normally. The timing of sampling will depend on the lenght of the menstrual cycle.
- To determine if and when ovulation has occurred following drug therapy to induce ovulation, as part of fertility treatment.
- When symptoms, such as abdominal pain and spotting, suggest an ectopic pregnancy or threatened miscarriage
- When a non-pregnant woman is experiencing abnormal uterine bleeding
What does the test result mean?
Interpretation of progesterone test results requires accurate knowledge of where a woman is in her menstrual cycle or pregnancy. Progesterone concentrations in the blood usually start to rise when an egg is released from the ovary, continue to rise for several days, and then either continue to rise with early pregnancy or fall to start menstruation.
If progesterone concentrations do not rise and fall on a monthly basis, a woman may not be ovulating or having menstrual periods. If concentrations do not rise normally during an early pregnancy, the pregnancy may be ectopic and/or may be failing.
Levels of progesterone will be naturally higher during pregnancies that involve multiples (twins, triplets, etc.) than those in which there is only one fetus.
Is there anything else I should know?
Taking oestrogen and progesterone supplements may cause inaccurate results.
Some oral contraceptive pills contain progesterone and may also cause inaccurate results.
Are men tested for progesterone?
No. Progesterone measurement does not have an established role in males.
Are there other uses for progesterone?
Yes. Progesterone (in the synthetic form progestogen) is often used in hormone replacement therapy (HRT) for menopausal women. However, the use of combined progestogen and oestrogen therapy has become controversial recently based on the findings of several research studies. For more information, read the NHS Choices pages on HRT. Progesterone is also used in some contraceptive pills.
If I am menopausal and on hormone replacement therapy (HRT), is there ever a need to monitor my progesterone level?
Adequacy of replacement therapy does not correlate well with measured hormone levels. However, if you still have your uterus and are having symptoms, such as unexplained uterine bleeding, your doctor may request a progesterone blood test along with other tests and procedures. If you do not have a uterus (removed during a hysterectomy), your HRT will not include progesterone.