# A Rare Case of Moderate Pericardial Effusion Uncovering Severe Hypothyroidism

## TL;DR

A 64-year-old woman with severe hypothyroidism showed moderate pericardial effusion, which resolved with hormone therapy, highlighting the link between thyroid issues and heart complications.

## Contribution

This case highlights the rare but reversible cardiovascular complication of pericardial effusion in severe hypothyroidism.

## Key findings

- Severe hypothyroidism was diagnosed in a patient with nonspecific symptoms and moderate pericardial effusion.
- Pericardial effusion resolved with levothyroxine therapy without the need for invasive procedures.
- The case emphasizes the importance of considering hypothyroidism in patients with unexplained systemic symptoms.

## Abstract

Severe hypothyroidism can manifest with various cardiovascular complications, including bradycardia, diastolic dysfunction, and, less commonly, pericardial effusion, due to thyroid hormone’s regulatory effects on cardiac function. While small pericardial effusions may be seen in clinical practice, large effusions and tamponade are rare. We present a case of a 64-year-old female patient with obesity who was initially admitted for bilateral lower extremity cellulitis. During her hospitalization, clinical signs such as lethargy, puffy facies, and slow speech raised concern for hypothyroidism, prompting thyroid function testing, which revealed severe hypothyroidism (thyroid-stimulating hormone 58.3 mIU/L, free T4 0.51 ng/dL). A transthoracic echocardiogram, obtained as part of further evaluation, demonstrated a moderate circumferential pericardial effusion without tamponade physiology. She was managed conservatively with oral levothyroxine, and cardiology advised against pericardiocentesis due to hemodynamic stability. Pericardial effusion in hypothyroidism typically resolves with hormone-replacement therapy. This case underscores the importance of considering hypothyroidism in patients with nonspecific systemic symptoms and highlights its potential to cause clinically significant but reversible cardiovascular complications.