Lutenizing hormone (LH) is a key part of the hypothalamic-pituitary-gonadal axis. It works in conjunction with follicle-stimulating hormone (FSH) to control reproductive function.
LH production is driven by gonadotropin-releasing hormone (GnRH).
LH release is controlled by the hypothalamus via gonadotropin-releasing hormone (GnRH) in a pulsatile manner.
LH is essential for reproductive health in both males and females:
Females: Triggers ovulation (the release of an egg) and stimulates the development of the corpus luteum.
Males: Stimulates Leydig cells in the testes to produce testosterone. Promotes maturation of primordial germ cells.
In males:
Stimulates Leydig cells in the testes to produce testosterone Supports sperm production indirectly (through testosterone)
In boys, LH stimulates testicular Leydig cells to produce and release testosterone and insulin-like3.
In Women: They trigger the release of estrogen and progesterone, which are vital for the menstrual cycle, ovulation, and pregnancy.
In girls, LH stimulates ovarian theta cells to produce androgens, which enter adjacent granulosa cells and FSH induced aromatization in these cells results in estradiol production. Stimulates formation of the corpus luteum, which produces progesterone Works with follicle-stimulating hormone (FSH) to regulate the menstrual cycle
LH in the menstrual cycle: LH levels are usually low during most of the cycle sharp “LH surge” mid-cycle triggers ovulation
The activation of hypothalamic-pituitary-gonadal axis in puberty is proceeded by two early periods of hormonal activity, the first during fetal life, the second during infancy (puberty).
Luteinizing hormone (LH) is a hormone produced by the anterior pituitary gland that is essential for human reproduction.
In women, an LH surge triggers ovulation, while in men, it stimulates testosterone production.
Normal LH levels fluctuate with the menstrual cycle, but abnormal levels can indicate pituitary disorders, infertility, PCOS, or pubertal issues.
LH levels fluctuate based on the menstrual cycle stage, age, and sex, often measured in international units per liter (IU/L).
Adult Women (Follicular phase): ~1-12 IU/L. Adult Women (Mid-cycle surge): ~16-104 IU/L. Adult Women (Luteal phase): ~1-12 IU/L. Adult Men: ~1-8 IU/L.
Symptoms of High LH Levels
High levels may indicate premature ovarian failure, Turner syndrome, or PCOS in women, and Klinefelter syndrome or testis dysfunction in men.
Symptoms include:
Infertility or trouble conceiving. Irregular or absent menstrual periods. Irregular vaginal discharge Low sex drive.
Symptoms of Low LH Levels Low LH, often indicating pituitary or hypothalamic issues, may cause secondary hypogonadism.
Women: Irregular/absent periods and infertility. Men: Low testosterone levels, low sperm count, and low libido. Children: Delayed puberty.
Clinical relevance
Abnormal LH levels can indicate:
High LH Polycystic Ovary Syndrome Primary ovarian failure Testicular failure
Low LH Pituitary or hypothalamic dysfunction Chronic illness, stress, or excessive exercise