Luteinizing Hormone (LH) – Interstitial Cell Stimulating Hormone

The Luteinizing Hormone (LH) test measures the level of LH in the blood. LH is a key reproductive hormone produced by the pituitary gland. In females, LH helps regulate the menstrual cycle and ovulation. In males, LH stimulates the production of testosterone by the testes (interstitial cells), which is why it is also known as interstitial cell stimulating hormone.

1. What Is LH?

• LH is a gonadotropin hormone released by the anterior pituitary gland.

• In women, LH surges mid-cycle and triggers ovulation and the release of an egg from the ovary.

• In men, LH stimulates Leydig (interstitial) cells in the testes to produce testosterone.

2. Why Is the LH Test Performed?

This test is used to:

• Evaluate fertility and reproductive function in both men and women.

• Diagnose disorders of the ovaries or testes.

• Help determine the cause of menstrual irregularities, early or delayed puberty.

• Monitor ovulation in fertility treatments or assess pituitary function.

3. LH Reference Ranges (May Vary by Lab)

• Women (follicular phase): 1.9 – 12.5 IU/L

• Women (ovulatory peak): 8.7 – 76.3 IU/L

• Women (luteal phase): 0.5 – 16.9 IU/L

• Postmenopausal women: 15.9 – 54.0 IU/L

• Men: 1.5 – 9.3 IU/L

4. Interpreting LH Results

🔹 Elevated LH:

• In women: May suggest PCOS (polycystic ovary syndrome), menopause, or ovulation.

• In men: May indicate testicular failure or androgen resistance.

🔹 Low LH:

• May suggest pituitary or hypothalamic dysfunction, anorexia, or secondary hypogonadism.

• In women, can cause absent or irregular periods; in men, low testosterone production.

5. What Can Affect LH Levels?

• Time in the menstrual cycle (LH levels fluctuate in women)

• Hormonal medications, birth control pills, or fertility drugs

• Stress, weight changes, or exercise intensity

• Pituitary or hypothalamic disorders

6. How Is the Test Performed?

• A blood sample is drawn from a vein, usually in the morning.

• Timing during the menstrual cycle is important for women and should be noted.

7. When to See a Doctor

🚨 Consult your healthcare provider if you:

• Are experiencing irregular periods, infertility, or early/delayed puberty.

• Are undergoing fertility treatment or hormone therapy.

• Have symptoms of hormone imbalance (e.g., fatigue, low libido, abnormal hair growth).

🔹 Key Takeaways

✅ LH plays a crucial role in reproductive health and fertility for both sexes.

✅ Test results help diagnose hormonal, pituitary, or gonadal conditions.

✅ Proper timing and interpretation are key, especially in women.