Letters Section Editor: Robert M. Golub,
MD, Senior Editor.
In Reply: Dr Caraccio and colleagues1 raise important issues concerning risks of cardiovascular
disease in subclinical hypothyroidism. Although a strong case can be made
for recommending levothyroxine treatment for patients with serum TSH levels
of more than 10 mIU/L, data supporting cardiovascular benefits of treatment
when TSH level is minimally increased (>4.5 to ≤10 mIU/L) are weak and
conflicting. The latter group constitutes about 80% of patients with subclinical
hypothyroidism, representing millions of mainly older people, many of whom
already have heart disease or have risk factors for heart disease. Studies
of subclinical hypothyroidism are challenging because the magnitude of change
and response to treatment of different parameters would likely be small and
difficult to distinguish from controls. Also, large numbers of patients with
serum TSH levels between 4.5 and 10 mIU/L are hard to find and maintain during
lengthy treatment with levothyroxine.
Surks MI. Subclinical Thyroid Disease and Cardiovascular Disease—Reply. JAMA. 2005;293(9):1059-1060. doi:10.1001/jama.293.9.1060-a