Restoration of euthyroidism does not improve cardiovascular risk factors in patients with subclinical hypothyroidism in the short term.

Subclinical hypothyroidism (SH) is being accepted as a condition that is associated with increased risk of cardiovascular disease. Restoration of euthyroidism might be involved in prevention of cardiovascular disease. Thus, we evaluated biochemical risk factors of 75 patients with SH without evidence of any other diseases before and after restoration of euthyroidism and compared to 27 healthy controls. Before and a mean of 18.2+/-4.4 weeks after restoration of euthyroidism, serum total and LDL cholesterol, lipoprotein (Lp) (a), total homocysteine (t-Hyc) and highly sensitive C-reactive protein (hsCRP) levels were analyzed. Pre-treatment levels of TSH (10.04+/-5.36 vs 1.74+/-1.1 mIU/l, p<0.05), total cholesterol (204+/-68 vs 179+/-26 mg/dl, p<0.05) and LDL cholesterol (129+/-50 vs 106+/-16 mg/dl, p<0.05) were significantly higher than controls while Lp (a), t-Hyc, and hsCRP levels were not different. None of these biochemical risk factors have improved after euthyroidism in patients with SH with average dose of 85+/-30 microg/day, when compared to pre-treatment levels. Only in a subgroup of patients (no. 30) with higher TSH levels (>10 mIU/l), did serum LDL cholesterol levels decrease significantly (139+/-38 vs 112+/-35 mg/dl, p<0.05). Lp (a), t-Hyc and hsCRP levels were not significantly different after treatment with levothyroxine therapy even in this subgroup of patients. We conclude that clinical management of SH does not contribute to prevention of cardiovascular disease in the short term, and monitoring risk factors of cardiovascular disease does not offer additional benefits for treating patients with SH.