LH
Also known as: Luteinizing Hormone
What Does LH Measure?
Luteinizing Hormone (LH) is a gonadotropin hormone produced and released by the pituitary gland, a small gland located at the base of the brain. A blood test for LH measures the concentration of this hormone circulating in the bloodstream, typically expressed in International Units per Liter (IU/L). LH plays a central role in regulating the reproductive system in both males and females by acting on the gonads — the ovaries in women and the testes in men.
Why Does LH Matter?
In women, LH is best known for triggering ovulation. Midway through the menstrual cycle, a sharp surge in LH — called the 'LH surge' — signals the ovary to release a mature egg, making it the key hormonal event in fertility. LH also stimulates the production of estrogen and progesterone throughout the cycle. In men, LH stimulates cells in the testes called Leydig cells to produce testosterone, which is essential for sperm production, muscle mass, bone density, and overall male health. Abnormal LH levels can indicate conditions ranging from polycystic ovary syndrome (PCOS) and premature ovarian failure in women, to hypogonadism and pituitary disorders in both sexes, making it a critical marker for evaluating fertility, hormonal balance, and reproductive health.
Normal Ranges
Males
Adult males: 1.7–8.6 IU/L
Females
Follicular phase: 2.4–12.6 IU/L; Ovulatory surge: 14–96 IU/L; Luteal phase: 1.0–11.4 IU/L; Postmenopause: 7.7–58.5 IU/L
Children
Prepubertal: 0.02–0.3 IU/L; values rise significantly during puberty
Causes of High Levels
- Primary hypogonadism (ovarian or testicular failure) — the pituitary overproduces LH in an attempt to stimulate non-functional gonads
- Polycystic ovary syndrome (PCOS) — often characterized by an elevated LH-to-FSH ratio (≥2:1), disrupting normal ovulation
- Menopause or premature ovarian insufficiency — loss of ovarian function removes negative feedback, causing LH to rise sharply
- Pituitary adenoma (LH-secreting tumor) — rare benign tumors can autonomously overproduce LH
- Klinefelter syndrome — a chromosomal condition in males (XXY) associated with testicular failure and elevated gonadotropins
- Normal ovulatory LH surge — a transient physiological spike around day 14 of the menstrual cycle is entirely normal
Causes of Low Levels
- Hypothalamic or pituitary dysfunction (secondary hypogonadism) — damage or disease affecting the hypothalamus or pituitary reduces LH secretion
- Kallmann syndrome — a genetic condition causing GnRH deficiency, leading to low LH and delayed or absent puberty
How to Improve Your LH
Diet
- Maintain a balanced, calorie-sufficient diet rich in whole foods to support healthy hypothalamic signaling — severe caloric deficits suppress LH
- Include adequate healthy fats (avocados, olive oil, nuts, fatty fish) as cholesterol is a precursor to sex hormones and supports LH-driven hormone production
- Eat zinc-rich foods such as oysters, beef, pumpkin seeds, and lentils, as zinc is essential for pituitary function and LH release
- Limit processed foods and refined sugars to reduce insulin resistance, which is linked to elevated LH levels in PCOS
- Ensure adequate intake of antioxidant-rich fruits and vegetables (berries, leafy greens) to reduce oxidative stress that can impair pituitary function
Supplements
- Zinc: 15–30 mg/day — supports gonadotropin synthesis and can help normalize LH levels in deficient individuals
- Vitamin D: 1,000–4,000 IU/day — vitamin D receptors are present in the pituitary and ovaries; deficiency is linked to disrupted LH signaling
- Myo-inositol: 2,000–4,000 mg/day — particularly for women with PCOS, shown in studies to help normalize the LH:FSH ratio and restore ovulation
- Ashwagandha (Withania somnifera): 300–600 mg/day — an adaptogen that may help reduce stress-related suppression of LH in both men and women
Related Biomarkers
Frequently Asked Questions
What is a normal LH level for ovulation, and how do I know if I'm ovulating?
During a normal menstrual cycle, LH surges dramatically — typically rising to 14–96 IU/L — about 24–36 hours before ovulation. This is the event that triggers the release of a mature egg. At-home ovulation predictor kits (OPKs) detect this LH surge in urine. A blood LH test taken at the right time of your cycle can confirm whether a surge is occurring. If your LH never surges or remains consistently low, it may indicate anovulation (lack of ovulation), which a doctor can investigate.
What does a high LH-to-FSH ratio mean?
In women of reproductive age, a high LH:FSH ratio — typically greater than 2:1 or 3:1 — is a classic finding in polycystic ovary syndrome (PCOS). Normally, LH and FSH levels are roughly similar in the early follicular phase. When LH is disproportionately elevated, it can interfere with normal follicle development and prevent ovulation. This ratio is just one diagnostic clue and must be interpreted alongside symptoms, ultrasound findings, and other hormone tests.
Can stress affect LH levels?
Yes, significantly. Chronic psychological or physical stress causes the adrenal glands to release cortisol, which directly suppresses the hypothalamus from releasing GnRH (gonadotropin-releasing hormone). Since GnRH is the signal that tells the pituitary to release LH, chronically elevated cortisol can reduce LH pulses and disrupt the entire reproductive axis. This is why conditions like hypothalamic amenorrhea — often seen in athletes, people under extreme stress, or those with eating disorders — result in low LH and loss of periods.