Background: Thyroid hormone deficiency is associated with increased cardiovascular morbidity, which cannot be fully explained by the atherogenic changes in lipid profile observed in these patients. Hyperhomocysteinemia could help to explain the increased risk for arteriosclerotic coronary artery disease in hypothyroidism because is an important and independent risk factor for cardiovascular disease. Hypothyroidism decreases hepatic levels of enzymes involved in the remethylation pathway of homocysteine.
Aim: Hypothyroid (TSH>10 mIU/l, low fT4 and fT3) were compared with hyperthyroid patients and euthyroid control to examine the relationship among homocysteine serum levels and thyroid hormonal status.
Material: Of 99 patients with hypothyroidism (2759 years of age): 44 with autoimmune thyroiditis and 54 after thyroidectomy for thyroid multinodular goiter or carcinoma. 63 patients with hypothyroidism (2361 years of age): 28 with toxic nodular goiter and 35 with Graves disease. Control group was consisted of 30 healthy volunteers.
Methods: Homocysteine serum concentration was measured by fluorimetric HPLC.
Results: Serum homocysteine levels were significantly higher in patients with hypothyroidism in comparison with those of healthy controls (19.1±8.4 vs 10.2±2.7 μmol/l, P<0.05). Homocysteine levels were positively related to TSH blood concentrations and inversely related to folates. Thyroid hormone replacement significantly decreased homocysteine serum levels. There were no differences in homocysteine levels between patients with hyperthyroidism and healthy controls.
Conclusion: We found an increase in serum homocysteine during hypothyroidism. The increase in serum homocysteine concentration may confer increased cardiovascular risk in hypothyroid patients.