Report of an association between race and thyroid stimulating hormone level.

We examined the association between race and thyroid stimulating hormone (TSH) level in 809 consecutive Black or White adults tested for mild suspicion of hypothyroidism with a normal TSH result. The mean TSH level of Blacks was 0.4 (SE .053) mU/L lower than that for Whites after age and sex adjustment, race explaining 6.5 percent of the variation in TSH levels. A validation sample yield similar results. This finding supports the possibility that differences in thyroid function and/or regulation may be associated with race.