What should you know about an LH blood test?

LH changes during the menstrual cycle and is interpreted differently in pregnancy, menopause and people taking hormonal medicines. A result is considered alongside follicle-stimulating hormone, oestrogen, progesterone or testosterone when relevant. An altered LH level can have multiple explanations, including pituitary conditions, ovarian or testicular problems, low energy availability, chronic illness or medicines; it does not identify one cause alone.

Tell the clinician the first day of your last menstrual period, whether your cycles are regular, and whether pregnancy is possible. Mention contraception, fertility treatment, hormone therapy and supplements. Ask whether the sample should be taken on a particular cycle day. Keep the laboratory report because the reference range and timing help make the result useful.

Seek prompt advice for very heavy bleeding, severe pelvic pain, fainting, sudden severe headache or new vision changes. Urgent assessment is needed for collapse, severe weakness or symptoms during a possible pregnancy. A raised or low LH result without an emergency symptom generally needs a planned review rather than immediate treatment.

Ask what your LH result means for your age and cycle stage, which additional hormones are needed, and whether the test should be repeated. Discuss how medicines or contraception may affect the result and what the next step is for your symptoms or fertility plans.