All That Glitters Like Gold Is Not Good: A Rare Constellation of Pericardial Effusion Without Cardiac Tamponade and Biochemical Myopathy in Hypothyroidism.

Severe hypothyroidism can present with a wide range of clinical manifestations, often involving multiple organ systems and mimicking primary cardiac or metabolic disorders. We report the case of a 45-year-old man who presented with chest pain, marked bradycardia, and moderate pericardial effusion, along with bicytopenia and rhabdomyolysis. Initial evaluation raised suspicion for acute coronary syndrome; however, laboratory testing revealed markedly elevated thyroid-stimulating hormone and low free thyroxine levels, confirming the diagnosis of severe primary hypothyroidism. The patient demonstrated gradual clinical improvement with levothyroxine therapy, including resolution of bradycardia, pericardial effusion, and biochemical abnormalities. This case highlights the importance of maintaining a high index of suspicion for hypothyroidism in patients presenting with unexplained cardiovascular or neuromuscular symptoms. Early recognition and appropriate thyroid hormone replacement can prevent potentially life-threatening complications and avoid unnecessary invasive interventions.