FSH is often used in conjunction with other tests (LH, testosterone, estradiol, and progesterone) in the workup of infertility in both men and women. FSH 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 or precocious (early) puberty.

In women and men, FSH and LH are ordered as part of the workup of infertility and pituitary disorders. FSH may also be ordered to determine if a woman has reached menopause. FSH levels also help to determine the reason a man has a low sperm count. In children, FSH and LH 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, FSH and LH levels can help to differentiate between primary ovarian failure (failure of the ovaries themselves) and secondary ovarian failure (failure of the ovaries due to disorders of either the pituitary or the hypothalamus). Increased levels of FSH and LH are consistent with 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, FSH levels will rise.

Low levels of FSH and LH are consistent with secondary ovarian failure due to a pituitary or hypothalamic problem.

In men, high FSH levels are due to primary testicular failure. This can be due to developmental defects in testicular growth or to testicular injury, as indicated 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 FSH and LH 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.

FSH results can be increased with use of cimetidine, clomiphene, digitalis, and levodopa. FSH results can decrease with oral contraceptives, phenothiazines, and hormone treatments.