Luteinizing Hormone, Serum

Luteinizing Hormone, Serum (LH Test)

What it is

The Luteinizing Hormone (LH), Serum test measures the level of luteinizing hormone in the blood. LH is a hormone produced by the pituitary gland that plays a vital role in regulating the reproductive system. In women, LH helps trigger ovulation and supports ovarian hormone production, while in men it stimulates the testes to produce testosterone.

Uses

This test is used to evaluate fertility issues, diagnose reproductive disorders, and monitor hormonal imbalances. In women, it helps assess ovulation, irregular menstrual cycles, or causes of infertility. In men, it helps diagnose low testosterone, reduced sperm count, or pituitary gland disorders. It may also be ordered in children with early or delayed puberty.

Symptoms That May Lead to the Test

Doctors may recommend this test if you experience irregular or absent periods, difficulty conceiving, symptoms of menopause, decreased libido, erectile dysfunction, low energy, or delayed/precocious puberty in children. It may also be part of a hormonal workup alongside FSH, prolactin, and testosterone/estrogen tests.

Abnormal Results

High LH Levels: In women, may indicate menopause, polycystic ovary syndrome (PCOS), or ovarian failure. In men, high levels can suggest testicular damage. Elevated LH in children may indicate early puberty.

Low LH Levels: May point to pituitary gland dysfunction, hypothalamic disorders, malnutrition, excessive exercise, or certain chronic illnesses. In men, it may indicate secondary hypogonadism.

Risks

The test requires a routine blood draw, which carries minimal risks such as mild pain, bruising, or dizziness at the puncture site. These effects are temporary and generally harmless.