SAT-596 Hypothyroidism with Recurrent Pericardial Effusion Due to Medication Noncompliance

Introduction: Pericardial effusions have been associated with primary hypothyroidism, but are clinically asymptomatic and difficult to detect. It is a very rare cause of cardiac tamponade. We describe a patient with primary hypothyroidism presenting with recurrent pericardial effusions due to medication non-compliance. Clinical Case: A 67-year-old male was admitted to the hospital on two occasions with large pericardial effusion related to severe hypothyroidism, that was incidentally discovered on CT scan. His initial presentation was at age 63; when he was worked up with a CT abdomen for abdominal pain and was diagnosed with primary hypothyroidism with a TSH of 46.88 uIU/ml (reference range 0.35-4.94) and FT4 <0.40 ng/dl (reference range 0.70-1.48). A large pericardial effusion was noted as an incidental finding on the CT scan. Subsequent cardiac echocardiography (ECHO) reported a large predominately posterior cardiac effusion with no evidence of cardiac dysfunction or hemodynamic compromise. He was started on levothyroxine which was titrated over three months to 175mcg daily. Repeat cardiac ECHO, done with TSH: 6.09 uIU/ml and FT4: 0.77 ng/dl showed resolution of the pericardial effusion. He was lost to follow-up till 2015, when he as readmitted for severe abdominal pain and underwent sigmoidocolectomy for a colonic mass that was diagnosed as adenocarcinoma of colon. He was followed by oncology till his cancer was in remission. He had no follow up thyroid tests and had stopped taking levothyroxine for two years. In 2018, he had a CT chest/abdomen/pelvis for cancer surveillance that showed an unusually large pericardial effusion that was not present on prior CT scan in 2016. He had a follow up cardiac ECHO with a large, generalized pericardial effusion without evidence of cardiac tamponade. He was asymptomatic with a TSH: 60.74 uIU/ml and FT4: <0.40 ng/dl. Levothyroxine replacement was restarted, and he was followed in endocrine clinic, and the dose of levothyroxine titrated over three months based on labs till TSH was 3.74 uIU/ml and FT4: 1.26 ng/dl on full replacement dose of levothyroxine at 200mcg daily. Repeat cardiac ECHO showed a small, generalized pericardial effusion with no evidence of tamponade Conclusions: In conclusion, this case demonstrates one of the many cardiovascular manifestations of hypothyroidism including pericardial effusion. It highlights the importance of recognizing and treating it appropriately with thyroid hormone replacement and not by needle or surgical decompression, thus resulting in near complete resolution of the pericardial effusion. It also illustrates the importance of monitoring compliance of levothyroxine therapy. The pericardial effusions secondary to hypothyroidism can present as a diagnostic challenge when seen incidentally during work up of other underlying disorders.