LH is often used in conjunction with other tests (FSH, testosterone, estradiol and progesterone) in the workup of infertility in both men and women. LH levels are also useful in the investigation of menstrual irregularities and to aid in the diagnosis of pituitary disorders. In children, FSH and LH are used to diagnose delayed and precocious (early) puberty.

In women and men, LH (along with FSH) is ordered as part of the workup of infertility and pituitary disorders.

LH and FSH may be ordered when a boy or girl does not appear to be entering puberty at an appropriate age (either too late or too soon).

In women, LH and FSH levels can help to differentiate between primary ovarian failure (failure of the ovaries themselves or lack of ovarian development) and secondary ovarian failure (failure of the ovaries due to disorders of either the pituitary or the hypothalamus). Increased levels of LH and FSH are seen in primary ovarian failure. Some causes of primary ovarian failure are listed below.

Developmental defects:

• Ovarian agenesis (failure to develop ovaries) 
• Chromosomal abnormality, such as Turner’s syndrome
• Ovarian steroidogenesis defect such as 17 alpha hydroxylase deficiency

Premature ovarian failure due to:

• Radiation 
• Chemotherapy 
• Autoimmune disease

Chronic anovulation (failure to ovulate) due to: 

• Polycystic ovary syndrome (PCOS)
• Adrenal disease 
• Thyroid disease 
• Ovarian tumor

When a woman enters menopause and her ovaries stop working, LH levels will rise.

Low levels of LH and FSH are seen in secondary ovarian failure and indicate a problem with the pituitary or hypothalamus.

In men, high LH levels indicate primary testicular failure. This can be due to developmental defects in testicular growth or to testicular injury, as described below.

Developmental defects: 

• Gonadal agenesis 
• Chromosomal abnormality, such as Klinefelters syndrome

Testicular failure: 

• Viral infection (mumps) 
• Trauma 
• Radiation 
• Chemotherapy 
• Autoimmune disease 
• Germ cell tumor

Low levels are consistent with pituitary or hypothalamic disorders.

In young children, high levels of LH and FSH and development of secondary sexual characteristics at an unusually young age are an indication of precocious puberty. This is much more common in girls than in boys.

PLEASE NOTE: Numerically reported test results are interpreted according to the test's reference range, which may vary by the patient's age, sex, as well as the instrumentation or kit used to perform the test. A specific result within the reference (normal) range – for any test – does not ensure health just as a result outside the reference range may not indicate disease. To learn more about reference ranges, please see the article, Reference Ranges and What They Mean. To learn the reference range for your test, consult your doctor or laboratorian. Lab Tests Online recommends you consult your physician to discuss your test results as a part of a complete medical examination.

Some drugs can cause LH to increase, such as anticonvulsants, clomiphene, and naloxone, while others cause LH to decrease, such as digoxin, oral contraceptives, and hormone treatments.