Cardiovascular mortality in subclinicalhyperthyroidism: an ongoing dilemma.

The association of endogenous subclinical hyperthyroidism (SHyper) with cardiovascular mortality is controversial. This may reflect the different causes of endogenous SHyper in the population studied due to differences in iodine intake, and different selection criteria, e.g. sex, age, and race, the cutoff for serum TSH level, the duration of follow-up, and the presence of co-morbidities. A small sample size of SHyper patients could have caused a low statistical power in some of these studies. In other studies, the results were not adjusted for relevant confounders. Importantly, various meta-analyses have also given conflicting results