Hypothyroidism Presenting Atypically as an Isolated Pericardial and Pleural Effusion: A Case Report.

Hypothyroidism is an endocrine disorder characterized by low thyroid hormone levels, which commonly presents as fatigue, cold intolerance, constipation, poor memory and/or concentration, and weight gain. Common signs of hypothyroidism include bradycardia, electrocardiograph changes, a lower basal temperature, a slower relaxation phase of deep tendon reflexes, and swelling of the extremities. Hypothyroidism is diagnosed with labs showing high thyroid-stimulating hormone levels and low free thyroxine. Hypothyroidism may present as a pericardial or pleural effusion, with the incidence of each being unknown. The paucity of information regarding the incidence of pericardial and pleural effusions in hypothyroidism may be due to effusions being an atypical complication of a common endocrine disorder. Hypothyroidism, including in cases of pericardial or pleural effusions, is typically treated with thyroid hormone replacement therapy, usually in the form of levothyroxine. Hemodynamic compromise may necessitate pericardiocentesis or pleurocentesis. In this case report, we present an atypical presentation of hypothyroidism that is characterized by an isolated pericardial and pleural effusion in a patient with post-thyroidectomy hypothyroidism who was non-adherent to levothyroxine. We discuss the pathophysiology of pleural and pericardial effusions in thyroid disease, which is thought to involve increased capillary permeability and changes in oncotic pressure related to albumin. We also review treatment strategies regarding pericardial and pleural effusions in hypothyroidism.