Effects of folic acid plus levothyroxine on serum homocysteine level in hypothyroidism

Background: Rise in serum homocysteine level may be associated with higher prevalence of cardiovascular diseases in hypothyroidism. Levothyroxine can partly diminish serum homocysteine level. Folic acid participates in homocysteine metabolic cycle in the human body. The effect of concomitant administration of folic acid and levothyroxine on serum homocysteine level was evaluated in the present study. Methods: Sixty patients with hypothyroidism participated in this double-blinded clinical trial study. They were divided into two equal groups Group A received oral levothyroxine 50-100 µg daily. Group B took oral folic acid 1 mg on a daily basis in addition to levothyroxine with similar schedule to group A. The patients were followed up for two months. The serum homocysteine levels of these two groups were measured before and after the study. This study was registered in Iranian Registry of clinical trial (IRCT number: 201112077723N1). Results: Mean serum homocysteine level fell from 11.5±4.2 to 9.9±3.5 mol/lit and from 11.2±3.1 to 6.9±1.9 mol/lit in group A and B, respectively (p<0.001). The mean reduction in serum homocysteine levels were 1.6±1.2 mol/lit and 4.3±1.4 mol/lit in group A and B, respectively (p<0.001). Conclusion: Levothyroxine can decrease serum homocysteine level partly still its combination with folic acid empowers the effect. Combination therapy declines serum homocysteine level more successfully.