Hypothyroidism is a well-known cause of pericardial effusion (with an incidence of 3%–37%) and can cause cardiac tamponade in severe cases. In this review, we present the current knowledge on the epidemiology of hypothyroid-induced pericardial diseases, the mechanism through which low thyroid hormone levels affect the pericardium, the associated clinical manifestations, diagnostic tests and management options. Hypothyroidism causes pericardial effusion through increased permeability of the epicardial vessels and decreased lymphatic drainage of albumin, resulting in accumulation of fluid in the pericardial space. Interestingly, autoimmunity does not seem to play a major role in the pathophysiology, and a majority of effusions are asymptomatic due to slow fluid accumulation. The diagnosis is generally made when the pericardial disease is associated with an elevated thyroid-stimulating hormone level, and other secondary causes are excluded. Management consists of thyroid replacement therapy, along with pericardial drainage in case of tamponade.
In conclusion, hypothyroidism-induced pericardial diseases are underdiagnosed. Initiating treatment early in the disease process and preventing complications relies on early diagnosis through systematic screening per guidelines.