Massive pleural and pericardial effusion due to hypothyroidism in a patient with a surgically treated thyroid-stimulating hormone-producing pituitary adenoma.

Hypothyroidism is relatively rare etiology of serositis with effusion, but massive pleural effusion is very unusual. This is a report of massive pleural effusion in patient taking methimazole after surgical resection of thyroid-stimulating hormone (TSH)-producing pituitary adenoma (TSHoma). The patient was clinically and biochemically hypothyroid and responded well to discontinuation of methimazole and thyroid hormone replacement therapy. When assessing patients with pleural effusion, we should not rely on laboratory test results alone, as a detailed medical history and thorough physical examination could be more useful.