Objective: Subclinical hyperthyroidism (SHyper), defined as reduced thyrotropin with free hormones within the reference range, is a common medical finding, in particular in elderly people. In the last years has gained attention due to its health-related conditions, in particular at the cardiovascular level.
Materials and methods: We searched electronic database (PubMed) and search engines (Google Scholar) of articles and reviews using the terms "subclinical hyperthyroidism", "Atrial fibrillation", Ischemic stroke", "Hypertension", Heart failure", and "Mortality".
Results: Subclinical hyperthyroidism was clearly associated with the onset of atrial fibrillation and, consequently, with ischemic stroke. However, the latter association is less clear. The effect on hypertension is doubtful and fair. Subclinical hyperthyroidism could increase the risk of acute heart failure, possibly by increasing heart rhythm. Data on mortality are scanty but seem to suggest a possible association, probably linked to the detrimental effect on the cardiovascular system.
Conclusions: Current findings mainly described possible associations with rhythm alterations, heart failure, and stroke but the effective beneficial effects of the treatment of subclinical hyperthyroidism are still lacking.