What can an LH test tell you?
The main reason to measure LH is to check how well the hypothalamus, pituitary gland, and testes are working together. This relationship is also known as the hypothalamic-pituitary-gonadal (HPG) axis.
Your provider may use an LH test to:
Differentiate between primary and secondary hypogonadism. If you have clinically low testosterone, an LH test can help uncover the root of the problem. Low testosterone with elevated LH and FSH may indicate testicular failure (primary), while low testosterone with low or low-normal LH and FSH may suggest hypothalamic or pituitary dysfunction (secondary). Understanding this distinction can guide treatment.
Contextualize fertility concerns. If you’re having trouble conceiving, an LH test may provide helpful context. Abnormally low LH levels may be associated with low sperm count or reduced testosterone, both of which can affect fertility. Support a guideline-based evaluation of low testosterone. The American Urological Association recommends collecting two separate early-morning total testosterone levels and obtaining LH (±FSH) to classify hypogonadism and guide the next steps.
What is being tested?
Luteinizing hormone is a peptide hormone that the pituitary gland releases in pulses. Each pulse stimulates the Leydig cells in the testes to convert cholesterol into testosterone, the key hormone that drives sperm production, muscle and bone strength, and libido. This process depends on a tightly regulated feedback loop, with rising testosterone levels signaling the hypothalamus and pituitary glands to reduce their release of GnRH and LH to maintain balance.
LH secretion follows a pulsatile and circadian rhythm, with higher levels typically seen in the early morning. When this signaling pattern is disrupted — whether by pituitary dysfunction, testicular damage, or altered hypothalamic signaling — testosterone production can decline, affecting reproductive, sexual, and metabolic health. Research on male hypogonadism shows that defects anywhere along this hypothalamic-pituitary-testicular axis can lead to hormone imbalance and related symptoms.
Where is the LH test typically included?
LH is not part of common general health panels, like the comprehensive metabolic panel (CMP). A provider may order it individually or as part of a male fertility or hormone evaluation, alongside testosterone, FSH, and prolactin.
Who should get an LH test?
A provider may recommend LH testing if you have:
Symptoms of low testosterone. Symptoms of low testosterone include low libido, erectile dysfunction, fatigue, decreased muscle mass, and increased body fat.
Abnormal semen parameters. If you have a low sperm count or other semen abnormalities, especially alongside low testosterone, your provider may order an LH test to help identify the cause. Providers typically advise men with low sperm count (<15 million per milliliter) and low testosterone to get their LH levels tested.
Signs of pituitary disease. If your provider suspects a pituitary tumor due to unexplained symptoms like headaches, vision problems, and nausea, they may recommend LH testing alongside other pituitary hormones.
Monitoring of therapy. Testosterone replacement therapy (TRT) can suppress LH production and lower LH levels. When you stop treatment or switch to a fertility-safe option, your provider may check LH to see if sperm production is recovering.
Currently, no U.S. organization recommends routine LH screening in asymptomatic men. Testing is targeted based on symptoms and related lab findings.
