Hormone Test
Luteinizing Hormone (LH) Test
A comprehensive guide to the Luteinizing Hormone (LH) test, explaining its critical role in ovulation, sperm production, and diagnosing fertility issues in both men and women.
Test Overview
Luteinizing Hormone (LH) checks the functioning of ovaries in women and testes in men. It is released by the pituitary gland.
Key Timing
For fertility investigations, the test is preferably done on Day 3 of the menstrual cycle. Results from Day 2 to Day 4 are typically acceptable.
1. Purpose and Uses of the LH Test
The LH test is usually performed alongside FSH and other hormones to check sexual function and reproductive potential.
In Women
- Find the reason for infertility (struggling to conceive after 12 months).
- Predict the time of ovulation.
- Check the functioning of ovaries and ovarian reserves.
- Investigate irregular or absent periods (amenorrhea).
- Confirm the onset of perimenopause or menopause.
In Men
- Diagnose infertility or low sperm count.
- Find the reason for low sex drive.
- Check the functioning of testicles.
2. Procedure and Timing
This is a standard blood test drawn from a vein in the arm. In rare cases, it can be tested via urine.
When to Test?
For women, the timing is crucial. The test is preferably done on Day 3 of the menstrual cycle. At this time, your body must produce more LH if your ovarian reserves are low or fertility is declining.
Important Preparation
Medication Check: If you are taking birth control or other hormone pills, you may be asked to stop them at least four weeks before the test, as they can lower natural LH levels. Always consult your doctor before stopping medication.
3. How LH Works
The Luteinizing hormone is regulated by the hypothalamic-pituitary-gonadal axis. The Hypothalamus releases GnRH, which stimulates the pituitary to release LH.
- In Women: LH signals the ovaries to produce estradiol in the follicular phase. A mid-cycle LH Surge causes the mature follicle to release an egg (ovulation).
- In Men: LH stimulates the Leydig cells in the testes to produce testosterone, which regulates spermatogenesis (sperm production).
4. Normal Levels
LH values vary significantly depending on the phase of your cycle. The following are general reference ranges:
| Phase / Group | Normal Range (mIU/mL) |
|---|---|
| Follicular Phase (Day 1-14) | 1.37 – 9.0 |
| Midcycle Peak (Ovulation) | 6.17 – 17.2 |
| Luteal Phase (Day 14-28) | 1.09 – 9.2 |
| Postmenopausal | 19.3 – 58.0 |
| Men | 1.42 – 15.4 |
5. Interpreting Results
High LH Levels
- PCOS: High LH (especially if higher than FSH) is a common indicator of Polycystic Ovarian Syndrome.
- Ovarian Failure: High levels may indicate age-related infertility or menopause.
- Testicular Issues: High LH can indicate testicle damage or Klinefelter’s syndrome.
Low LH Levels
- Pituitary Dysfunction: Indicates a problem with the pituitary or hypothalamus.
- Malnutrition: Eating disorders can suppress LH production.
- Delayed Puberty: Very low LH in children may require evaluation.
6. LH Surge and IVF
For IVF cycles, optimal Day 3 LH levels are generally between 2.4 and 12.6 mIU/mL.
- Premature Surge: High LH can cause premature ovulation and affect egg quality.
- The LH Surge: Before ovulation, LH spikes (often around 45 mIU/mL).
- Timing: Used for timing IUI or intercourse.
Understanding your LH levels helps determine the best treatment protocol.