4.3 Strengths and limitations
Our study has several limitations. First, it was not possible to reliably assess the time of SCH and OH evolution. Longer evolution of the disease could translate into more changes in the carotid intima-media; however, all baseline characteristics in the study groups were similar, and patients themselves were the control when levothyroxine was used. Also, no follow-up monitoring was provided to SCH patients to evaluate a possible decrease or increase in the TSH level without treatment. The strengths of the study include a population with no cardiovascular risk factors or established cardiovascular disease. Carotid intima-media thickness is an atherosclerosis marker that has been evaluated in the prediction of cardiovascular risk. We had no losses to follow-up, and the ultrasound measurements were very reliable.
Conclusion
There is an association between an increase in the carotid intima-media thickness in patients with SCH and HC, even in SCH with TSH <10 µIU/mL; although that appears to be directly proportional to the TSH level. The increase was reversed with levothyroxine therapy at 6 months. We also found a weak positive association of carotid intima-media thickness with the anti-TPO level. Its association with important cardiovascular outcomes remains uncertain and should be studied in future studies.