A Rare Case of Massive Pericardial Effusion as the First Presentation of Hashimoto’s Hypothyroidism With Complete Resolution With Levothyroxine Treatment - A Case Report

Introduction: Hypothyroidism is a common endocrine disorder with multi-system involvement, with prevalence rate of 4.6% among the U.S. population. Clinical manifestations of hypothyroidism can vary widely from subclinical condition to multi-organ failure. One of the rare but serious complications of hypothyroidism is pericardial effusion (PE). To our knowledge, there are few case reports of PE secondary to hypothyroidism. We report a case of massive PE without tamponade secondary to hypothyroidism. Case Presentation: 52 year old obese male presented to the hospital with worsening dyspnea, dry cough, chest discomfort and lower extremity edema for 2 months. He was in mild respiratory distress, and afebrile. He had myxedematous facies, with dry skin. Thyroid gland was palpable. He was noted to have distant heart sounds and bradycardia with lower extremity edema and delayed deep tendon reflexes. Chest X-ray showed marked cardiomegaly suggestive of pericardial effusion. Laboratory testing was noted for elevated thyroid stimulating Hormone 55.9 mU/L, Low T4F <0.07 mU/L, low T3F 1.0 mU/L, and elevated Thyroid peroxidase antibodies of 520 IU/ml. Troponin-I, BNP, and D-Dimer were normal. Echocardiography showed left ventricular ejection fraction of 50%, and a large, free-flowing pericardial effusion >2 cm with focal strands. Patient was given intravenous Levothyroxine 100 mcg once, then was started on oral Levothyroxine 75 mcg daily. No pericardiocentesis was done. Patient was discharged and followed up after 6 month of treatment with resolution of his symptoms, facies, and pericardial effusion. Discussion: Hypothyroidism is predominant worldwide with reported prevalence rates of 5–10% in women and 1–3% in men. Common symptoms include: fatigue, cold intolerance, and constipation. Cardiovascular involvement is less common. Small PE has been reported in 10-30% of cases. Severe PE -with or without tamponade- is a very rare complication and is only linked to severe degrees of myxedema. A recent study evaluating 70 newly diagnosed adult hypothyroid patients showed mild PE prevalence of 17%, with moderate PE seen in only 1 patient (0.01%). Severe PE or tamponade was not observed in this cohort. The development of PE secondary to hypothyroidism is not well understood. Increased systemic capillary permeability and decreased lymphatic drainage of albumin which leads to increased pericardial colloid pressure are proposed mechanisms for hypothyroid PE. Most of hypothyroidism clinical symptoms can be reversed with thyroid hormone replacement within 1-15 months. Pericardiocentesis is reserved for symptomatic patients despite treatment, patients with tamponade or with persistent PE for more than 3 months. Our case sheds light on a rare, yet, serious complication of hypothyroidism, most likely explained by low socio-economic status. Hence the importance of patient education and proper follow up.