Typically, normal luteinizing hormone levels in fluctuate throughout the month. They also vary according to age and gender. Measuring these levels can predict ovulation in women, evaluate sperm counts in men and check for the presence of diseases or conditions, such as pituitary gland disorders.
Luteinizing hormone (LH) is produced by the anterior pituitary gland. It is called a gonadotropin, because it affects the ovaries in women and testes, or gonads, in men. LH stimulates both male and female gonads to produce testosterone, which is then converted to estrogen in females. Gonadotropin releasing hormone (GnRH) stimulates the production of luteinizing hormone. Once the hormones estrogen and testosterone have been produced, their levels inhibit the production of GnRH, and thus the production of LH.
In males who have entered puberty, normal luteinizing hormone levels range from 4 to 12 international units per milliliter. Females who have just entered puberty have levels that range from 2 to 14. These numbers will vary slightly form lab to lab. Testing luteinizing hormone in children can help diagnose early or delayed puberty, which may be caused by tumors or a pituitary gland disorder.
Normal luteinizing hormone levels in women of childbearing age range from 5 to 25 international units per liter, while those who have passed menopause range from 19 to 100. This value will typically be highest around the time of ovulation. A level that is higher than normal may indicate ovarian failure, menopause, polycystic ovary disease, or a missing or incomplete X chromosome. Lower than normal luteinizing hormone may point to a pituitary disorder.
Adult males have normal luteinizing hormone levels ranging from 1 to 15 international units per milliliter. Lower than normal luteinizing hormone levels in men can mean pituitary gland disorder. Higher than normal levels can mean absent testicles or testicular failure or an extra X chromosome.
Men and women who have higher or lower than normal luteinizing hormone are not fertile, and a blood test for LH is often ordered as part of a series of tests to find a cause for infertility. Both genders with primary infertility, which is caused by a problem with the gonads, will have high luteinizing hormone levels. Typically, those with secondary infertility, caused by problems with the secretion of LH, will have low numbers. Children who have entered puberty early due to a disorder will have higher than normal levels.