- Progesterone is used as a marker of ovulation in the investigation of infertility. Failure to ovulate is a reason for infertility in about 20% of cases. Failure of progesterone levels to increase in the latter phase of the menstrual cycle indicates an anovulatory cycle or corpus luteum inadequacy.
- A progesterone level of greater than 30nmol/L should be seen as a guideline to ovulation rather than an absolute measure. If the progesterone level is above 30nmol/L, further hormone levels are unnecessary and other causes of infertility must be explored.
- Take samples 7 days before the next predicted menstruation (e.g. day 21 of a 28 days cycle).
- If patient on high dose biotin therapy (>5mg/day) collect sample at least 8 hours after the last dose.
For adults, 5 ml of blood taken into a narrow gold top gel tube (or rust top for the Acute Unit)
Send at ambient temperature to the laboratory on the day of sample collection.
Relevant clinical details including day of menstrual cycle, cycle length and reason for request.
The assays are run throughout the day and night. The in-lab turnaround time is less than 24 hours.
Reference ranges are not given for progesterone results however, a serum progesterone of 30nmol/L or greater when measured 7 days before the next predicted menstruation (e.g. day 21 of a 28 day cycle) is good evidence of ovulation. Lower progesterone levels do not exclude the possibility of an ovulatory cycle.
(Ref: Hargreaves, T. B. & Mills, J. A. (1998) Investigating and managing infertility in general practice. BMJ 316; 1438-1441).