Thyroid Dysfunction Testing/Screening
Theresa Rohr-Kirchgraber, MD Eskenazi Women’s Center of Excellence
Melissa Cavaghan, MD Endocrine
For many women the symptoms of thyroid dysfunction are so familiar that it seems that everyone has at least one of the complaints. Fatigue, poor sleep, constipation, weight gain/loss, irregular menses, hair loss, and depression seem to be a part of daily life especially for women as they age. As a primary care physician, when should we screen for thyroid dysfunction and which test is the best screening test in a non-pregnant woman?
In the NHANES study which looked at over 13,000 asymptomatic people, about 5.9% had thyroid dysfunction. Thyroid dysfunction is at least five to eight times more common in women than men, and hypothyroidism is more common in women with small body size at birth and during childhood. Thyroid dysfunction increases with age as well so perhaps screening with a TSH is appropriate any patients who have any of the above complaints and/or coarse hair, myalgia, cold intolerance, or dry skin.
To screen, a high sensitivity TSH is the most cost effective and reliable test except in the uncommon case of pituitary disease. TSH with reflex T4 (T4 is measured by the laboratory only when the TSH is abnormal) is an alternative. Measurement of T3 is not needed as a screen and should not be used. Some do recommend both a TSH and T4 for screening, but a baseline TSH with a reflex test for T4 is considered the most cost effective.
Biotin, a common supplement for hair and nails, can interfere with the T4 assay so patients should remain off of biotin for three days prior to testing. Pregnancy, race, and obesity can be a factor in TSH results and a T4 can help to delineate the need for further action.
Screening for thyroid dysfunction, especially in women, can be useful and should be considered as part of the annual health exam.