Yield of hypothyroidism in symptomatic primary care patients

Symptoms suggestive of hypothyroidism are common in primary care practice, but the yield of this disorder from symptom-based testing has not been adequately evaluated. We attempted to determine this yield and examine the effect of various patient factors on its magnitude. The records of 982 consecutive primary care health maintenance organization patients who had a thyroid-stimulating hormone (TSH) determination for suspicion of hypothyroidism were reviewed. Forty-two (4.3%) had an increased TSH concentration on initial testing, but only 17 (1.7%) had a TSH level 5 mU/L or more above normal. Abnormal thyroid examination results and white vs black race were independently associated with a TSH concentration 5 mU/L or more above normal. Female sex and age did not significantly affect the odds of an elevated TSH concentration. The yield of hypothyroidism from symptom-based testing in this setting was quite low. Although increasing age and female sex are both strong determinants of the risk of hypothyroidism in the general population, neither factor permitted risk stratification in symptom-based testing. The strong racial association noted was not anticipated and requires confirmation.