Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are two key hormones released by the pituitary gland. They regulate the growth of follicles (eggs), stimulate estrogen production and play a key role in ovulation. Gynecologists and fertility specialists use these hormones to assess your ovarian reserve and the timing of
What is Follicle Stimulating Hormone (FSH)?
FSH induces the growth of follicles (containing immature eggs) early in your menstrual cycle. The higher the FSH levels early in a woman’s menstrual cycle, the harder the brain is working to stimulate the ovaries to mature an egg. This usually indicates a low follicle count and lower ovarian reserve. When women reach menopause (no menstrual bleeding for 12 months), FSH levels will remain high.
What could a high FSH mean?
You are menopausal or peri-menopausal (the period leading up to menopause)
You have PCOS
Rarely you can have a genetic abnormality (i.e. Turner’s syndrome)
What is Luteinizing Hormone (LH)?
LH is a hormone released by the pituitary gland. LH levels increase in what is commonly known as the “LH Surge” 36 hours prior to the release of an egg. Many over-the-counter ovulation kits measure LH hormone to predict ovulation
What is a ‘Basic Day 3 Hormone Panel’?
Your gynecologist or family doctor can order a ‘Day 3’ panel to assess ovarian reserve. A ‘Basic Day 3’ Panel includes Estradiol, FSH and LH.
‘Day 1’ is the 1st full of menstrual flow (this means not counting days when you have light spotting as Day 1. ‘Day 2’ is the day after ‘Day 1’. ‘Day 3’ is the day after ‘Day 2’ and is when you should go into the lab for testing. Normal results within a Day 3 panel generally indicate a normal ovarian reserve. There can be many other factors in assessing your fertility. This can provide a doctor with important information with respect to your reproductive potential.
What is an ‘Advanced Day 3 Hormone Panel’?
An Advanced Day 3 Hormone panel is ordered by some specialists to rule out other causes of infertility. This includes additional testing for Prolactin and Thyroid Stimulating Hormone (TSH). Abnormalities with these values can indicate other hormonal issues which might affect ovulation. An AMH level is often added-on to an Advanced Day 3 Panel.
When should I not do this testing?
If you are taking hormonal birth control (pill, patch intrauterine device) it will artificially impact the levels of day 3 hormones. The results will be more accurate if performed at least 1 month after you are off your contraception.
There are general guidelines doctors follow in determining the time to follow up with a specialist. In women aged < 35 without medical conditions, it is normal for it to take up to 12 months to conceive. We often see many patients worried about not conceiving after 4 or 5 months and advise that infertility investigations are not routinely necessary.
Age
When to see a specialist
< 35 Years
Have not conceived after 12 months
35-39
Have not conceived after 6 months
40
Immediate Referral
What is a ‘Day 21 Progesterone test?
In women with an average cycle length of 28 days, a progesterone level is drawn on day 21 to determine if they have successfully ovulated. A low progesterone level usually indicates you are not ovulating and a high progesterone level indicates successful ovulation. The timing of ‘Day 21’ can change based on the length of your cycle. Usually progesterone peaks 7 days after ovulation. Please reference the table below to determine your equivalent ‘Day 21’, if your cycles are longer or shorter than 28 days.
Cycle length may vary from month to month. Use the average of your cycle lengths across several months to determine the time of day to complete this test. If your cycles vary considerably (e.g. 28 days then 60 days), it is likely that you are not ovulating every month. You can schedule this test for day 21 after your current bleed. If you do not have a bleed, a random blood level will be less helpful and you can seek care from a gynecologist or fertility specialist to proceed with testing.
*Cycle Length = the total number of days from the start of your period to the start of your next period.
Average Cycle Length (Days)
Which day to complete the ‘Day 21 Progesterone’ Test
26
19
27
20
28
21
29
22
30
23
31
24
32
25
33
26
34
27
35
28
References
Lindsay TJ, Vitrikas KR. Evaluation and treatment of infertility. Am Fam Physician. 2015 Mar 1;91(5):308-14. Erratum in: Am Fam Physician. 2015 Sep 15;92 (6):437. PMID: 25822387.
