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.