LH and FSH in men: what these tests show about low testosterone

LH and FSH are pituitary hormones that tell the testicles what to do. When testosterone comes back low, they help show where the problem starts.

FSH and LH

LH and FSH on one order. They are read together, so the paired test fits most questions.

$59

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What the tests measure

Luteinizing hormone (LH) is made by the pituitary gland. In men it signals the testicles to produce testosterone, which supports sperm production (MedlinePlus, LH). Follicle-stimulating hormone (FSH) helps control how much sperm the testicles make and how healthy it is (MedlinePlus, FSH).

Why they help explain low testosterone

The Endocrine Society’s guideline recommends that men with hypogonadism have LH and FSH measured to distinguish primary hypogonadism (a testicular problem) from secondary hypogonadism (a pituitary or hypothalamic problem). It also suggests further evaluation of the cause afterward (Bhasin et al., 2018).

The guideline places this step after low testosterone has been confirmed. If you have not had a testosterone test yet, start there. The testosterone test guide explains how.

Who might consider it

MedlinePlus says providers may order LH or FSH when a man has been unable to get a partner pregnant after 12 months of trying, has a low sperm count, has less interest in sex than usual, or has lost muscle or body hair. They are also used when a pituitary or hypothalamus disorder is suspected. The two tests are often paired.

Which order to place

LH and FSH are interpreted together, and the seller offers them both as a pair and LH alone. The seller’s page says the LH-only test does not include FSH. For most questions the pair fits better than LH alone. The LH-only test makes sense only if your order names LH alone.

• LHLH only. Results are usually read with FSH $49 See this test at HealthLabs

Sold by HealthLabs. Prices checked October 2026. Not available in ND, RI, NY, NJ, MD and HI. We earn a commission on sales.

How to prepare

MedlinePlus says the test is a blood draw from an arm vein, and that you may need to stop certain medicines or supplements before an LH test. The seller’s page says fasting is not required, but that wording is shared across the seller’s single-test pages. Follow the instructions on your lab order.

Tell the person drawing your blood about all medicines and supplements. The Endocrine Society guideline notes that biotin can interfere with these assays and says clinicians should stop biotin supplements for at least 72 hours before testing. Ask your clinician or the lab before you stop a supplement. Don’t stop any prescription medicine unless your provider tells you to.

What a result can and can’t tell you

Labs set their own ranges. MedlinePlus gives no reference ranges for either test, so use the range on your report.

• High LH or FSH often points to a problem in the testicles that keeps them from making normal levels of sex hormones. MedlinePlus lists mumps, testicular injury, Klinefelter syndrome, a germ cell tumor, and damage from autoimmune disease, radiation or chemotherapy.
• Low LH or FSH in an adult is often a sign of a problem with the pituitary gland or hypothalamus.

What these tests can’t do: they don’t diagnose low testosterone and they don’t give a final cause. Results are read with your age, symptoms, medical history and testosterone results. Take them to a clinician. If you were told your testosterone is low, ask whether LH and FSH have been checked.