Upper limit of the normal range for thyrotropin-stimulating hormone is higher with increasing age [Corrigendum]

Correspondence: Oscar MP Jolobe 1 Philip Godlee Lodge, 842 Wilmslow Road, Manchester M20 2DS, UK Tel +44 16 1448 9034 Email [email protected] To the editor The assertion that aging is associated with a decreasing concentration of thyrotropin-stimulating hormone (TSH) in healthy elderly humans appears to be at odds with the observation that “TSH distribution shifts towards higher concentrations with age.” The latter conclusion was based on a study that analyzed the age-specific distribution of serum TSH in 14,376 disease-free subjects with negative thyroid antibody tests. In that study, the percentage of TSH measurements in the 2.5–4.5 mIU/L range progressively increased with age from approximately 6.5% in the 20–29-year age group to 23.9% in the 80 years and older age group. Likewise, the percentage of TSH measurements in the .4.5 mIU/L category progressively increased from 2.0% in the 20–29-year age group to 12% in the 80 years and older age group. According to the authors of the study, a corollary of these findings is that “the currently accepted high prevalence of subclinical hypothyroidism in older people, based on the current upper limit of the reference range, 4.5 mIU/L, may be an overestimate.” Extreme longevity also appears to be associated with an increase in TSH levels, at least in Ashkenazi Jews. In the latter study, TSH levels were compared in 232 Ashkenazi subjects of median age 97.7 years versus their younger, unrelated counterparts, consisting of 95 females of median age 69.7 years and 95 males of median age 72.3 years. All subjects were free of thyroid disease and also free of acute or debilitating medical conditions. The principal finding was that serum TSH was significantly (P , 0.001) higher in the older age group (consisting of 232 subjects) than in their younger counterparts (consisting of 190 subjects) in spite of the fact that the serum thyroxine levels were similar. Further analysis revealed that the percentage of subjects with TSH . 2.5 mIU/L was 35.2% in the older subjects versus 15.4% in the younger subjects.