How to prepare
No fasting is required. Eat and drink normally beforehand.
Cycle timing can be important depending on what is being investigated. For baseline assessment of pituitary function and PCOS, LH is typically tested early in the cycle (day 2 to 4). To detect the LH surge associated with ovulation, testing is done mid-cycle around day 12 to 14 (earlier or later for non-28-day cycles). Your practitioner will specify when to test based on your situation.
If you are not menstruating or are post-menopausal, timing is less critical. A healthcare professional will take a blood sample from a vein in your arm.
After the test
Share your results with your GP, gynaecologist, endocrinologist, or fertility specialist. LH is most informative when interpreted as part of a panel. If you are investigating PCOS, your practitioner will typically look at LH and FSH together. For fertility assessment, AMH and oestradiol usually accompany LH.
If LH results suggest a pituitary abnormality, further investigation including additional pituitary hormones and imaging may be recommended.
Your test results will be available in your private dashboard. If there are any urgent issues, we'll let you know so you can follow up with your health professional.
Understanding results
Results are reported in International Units per litre (IU/L). Reference ranges are specific to sex, age, and cycle phase — your result report will include the applicable range.
In women of reproductive age, early-cycle LH provides a baseline. An elevated LH-to-FSH ratio (greater than 2:1) in the early follicular phase is associated with PCOS. An LH surge (a rapid 2- to 3-fold rise) mid-cycle signals imminent ovulation. After menopause, LH is persistently elevated.
In men, low LH can point to a pituitary cause of low testosterone (secondary hypogonadism), while normal or high LH with low testosterone may indicate a testicular cause (primary hypogonadism).
Your practitioner will interpret LH alongside FSH, oestradiol, AMH, and other relevant markers.
