Luteinising hormone (LH)

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What is LH?
Where is LH produced?
Function of LH
The LH surge and ovulation
LH ovulation kits
Normal LH levels
Causes of high LH
Causes of low LH
LH in men
When and how to test LH
LH in traditional Chinese medicine
Acupuncture and LH
Chinese herbal medicine and LH
Diet, supplements and lifestyle
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1. What is LH?

Luteinising hormone (LH) is a glycoprotein hormone produced by the anterior pituitary gland. Together with FSH, it is one of the two gonadotrophins that drive reproduction in women and men. In women, LH triggers ovulation and supports the corpus luteum's production of progesterone. In men, LH stimulates the Leydig cells in the testes to produce testosterone.

Reference ranges vary from country to country and between laboratories. Always interpret your own result against the reference range provided by the laboratory that performed your test.

2. Where is LH produced?

LH is produced by gonadotroph cells in the anterior pituitary gland. The hypothalamus releases gonadotrophin-releasing hormone (GnRH) in pulses, and a faster pulse frequency favours LH release over FSH. LH is released during the daytime more than at night, and its secretion is controlled by feedback from oestrogens, progesterone and the rising follicle.

3. Function of LH

In women, LH:

Triggers ovulation through the mid-cycle LH surge.
Supports the final maturation of the dominant follicle and its rupture to release the egg into the fallopian tube.
Maintains the corpus luteum (the empty follicle sac) after ovulation, supporting its production of progesterone.
Stimulates the production of androgens by the theca cells of the ovary, which are then converted to oestrogens in the granulosa cells.

In men, LH stimulates the Leydig cells in the testes to produce testosterone.

4. The LH surge and ovulation

The LH surge is the dramatic increase in LH that triggers ovulation. As the dominant follicle matures, it produces increasingly high levels of oestradiol. When oestradiol crosses a threshold, it switches the pituitary's response from negative to positive feedback, causing a sudden rise in LH. The LH surge typically begins 34–36 hours before ovulation and peaks 10–12 hours before the egg is released. LH levels during the surge can rise to between 21.9 and 56.6 IU/mL, then fall rapidly.

The pituitary releases LH as a pulse rather than continuously, so LH levels during the surge fluctuate considerably. This pulsatile release is the reason why ovulation kits sometimes give false-negative results — the test may be performed during a trough between pulses.

5. LH ovulation kits

Home ovulation kits work by detecting the rise in urinary LH that accompanies the LH surge. They can be useful for timing intercourse, but have limitations:

The pulsatile nature of LH means tests can miss the surge between pulses.
Women with PCOS have chronically elevated LH and often get persistent positive results.
The surge does not always result in ovulation — luteinised unruptured follicle syndrome can occur.
Monitoring your own body — particularly cervical mucus, mid-cycle twinges, increased libido and a slight rise in basal body temperature — is often more reliable and less stressful.

6. Normal LH levels

The normal level of LH on day 2–3 of the menstrual cycle is approximately 2.1–12.6 IU/mL. During the LH surge, levels typically rise to 21.9–56.6 IU/mL. Reference ranges vary from country to country and between laboratories.

7. Causes of high LH

High LH (out of context of the surge) is most commonly seen in:

PCOS — the classical hormonal pattern is an LH:FSH ratio greater than 2:1, with both LH and total testosterone elevated.
Premature ovarian failure and menopause — both LH and FSH rise as the ovaries fail.
Removal or absence of the ovaries.

8. Causes of low LH

Low LH is seen in:

Hypothalamic amenorrhoea — caused by stress, low body fat or excessive exercise. Fasting and undereating reduce LH and can prevent ovulation entirely.
Hyperprolactinaemia.
Pituitary disease.
Use of GnRH agonists or oral contraceptives.

9. LH in men

In men, LH stimulates the Leydig cells of the testes to produce testosterone. Elevated LH in a man with low testosterone indicates testicular failure (primary hypogonadism), while low LH in a man with low testosterone points to a problem at the hypothalamus or pituitary (secondary hypogonadism).

10. When and how to test LH

Like FSH, baseline LH should be tested on day 2 or 3 of the menstrual cycle. The LH:FSH ratio at this time can help in the diagnosis of PCOS. The mid-cycle LH surge can be detected through urinary ovulation kits or through serial blood tests, although the pulsatile nature of LH means a single result can be misleading.

Reference ranges vary from country to country. Always interpret your own result against the laboratory's reference range and discuss it with your doctor.

11. LH in traditional Chinese medicine

In traditional Chinese medicine, the LH surge corresponds to the moment of yang activation that triggers ovulation. Disturbances of the LH surge — whether absent, weak or excessive — reflect imbalance in the Kidney Yang, Liver Qi or both. The chronically elevated LH of PCOS is most commonly seen as a pattern of Damp-Phlegm with Liver Qi stagnation and underlying Kidney deficiency.

12. Acupuncture and LH

Research has shown that acupuncture can regulate LH levels in women with PCOS, reducing the chronically elevated LH that drives androgen excess. Acupuncture has also been shown to support a healthy LH surge in women with luteal phase defect or weak ovulation. Treatment is individualised and typically given weekly for at least three menstrual cycles.

13. Chinese herbal medicine and LH

Chinese herbal formulae such as Bu Shen Tiao Chong Tang, Wen Jing Tang and Bu Zhong Yi Qi Tang are commonly used to support healthy LH function. Where the underlying pattern is Damp-Phlegm with Liver Qi stagnation (as in many PCOS patients), formulae such as Cang Fu Dao Tan Tang are used.

14. Diet, supplements and lifestyle

To support healthy LH function:

Avoid prolonged fasting or extreme dieting — both reduce LH and can stop ovulation.
Maintain a body fat percentage of at least 22%.
Consider maca root in higher doses (50 g per day) for low LH levels — research suggests it can increase LH in women.
For high LH (as in PCOS) — reduce refined sugar, gluten and dairy; address insulin resistance with diet, exercise and myo-inositol.
Sleep before 10 p.m. and aim for seven to eight hours per night.
Reduce psychological stress.