Enhancing Diagnosis: The Role of Point-of-Care Ultrasound in Early Detection of Pericardial Effusion in Post-Radioactive Iodine Hypothyroidism.

Pericardial effusion is a relatively common classical pericardial syndrome that poses a diagnostic challenge for clinicians. There are varying clinical presentations of pericardial effusion, ranging from asymptomatic incidental findings on chest X-ray (CXR) or point-of-care ultrasound (POCUS) to hemodynamic instability in cardiac tamponade. Pericardial effusion is a notable cardiac manifestation of severe and long-standing hypothyroidism. We report the case of a 57-year-old female with a previous history of Graves' disease treated with radioactive iodine (RAI) more than 30 years prior but who had never been followed up on post-RAI. Admission CXR depicted a water bottle-shaped cardiomegaly. POCUS portrayed a massive pericardial effusion with no echocardiographic evidence of cardiac tamponade. Laboratory investigations showed raised thyroid-stimulating hormone and low free thyroxine. The pericardial effusion gradually subsided during the surveillance echocardiogram after initiation of thyroid hormone replacement therapy. Early POCUS assessments in this case expedite the diagnosis and management of hypothyroidism-induced pericardial effusion. With timely and adequate thyroid hormone replacement therapy, pericardial effusion can be reversed, thereby averting the fatal complications of cardiac tamponade.