Screening and treatment for subclinical thyroid disease.

Abstract

To the Editor: In their Scientific Review and Clinical Applications article about subclinical thyroid disease, Dr Surks and colleagues stated that numerous small studies reveal subtle decreases in myocardial contractility in patients with subclinical hypothyroidism. Although the authors cited our review article in making this claim, they did not mention that we found diastolic dysfunction to be the most consistent cardiac abnormality in this disease. Furthermore, we reported that it tends to regress with replacement of thyroid hormone. This finding has been independently reported elsewhere. Furthermore, diastolic dysfunction has been reported not only in patients with thyroid-stimulating hormone (TSH) levels greater than 10 mU/L but also in those with TSH values between 4.5 and 10 mU/L. In contrast to this pattern with diastolic dysfunction, Surks et al reported that whereas lipid profiles are frequently abnormal when TSH levels are greater than 10 mU/L, they are seldom so in the lower TSH range. Thus, there appears to be a different target organ sensitivity to thyroid hormone deficiency, which may become clinically relevant depending on the patient’s thyroid function set-point. Collectively, these observations suggest that the decision to treat, rather than being based on a cutoff TSH threshold, should depend on the patient’s overall condition. We recommend that in the presence of a background of cardiovascular risk, replacement treatment should be considered regardless of the TSH concentration. On the other hand, simple clinical follow-up may be warranted in patients without cardiovascular risk and no other indications for thyroid hormone replacement.