New-Onset Heart Failure in the Setting of T4-Conversion Disorder.

Thyroid hormone is essential in accomplishing the appropriate metabolism of the body. Achieving euthyroidism is of importance due to the deadly ramifications of being hypothyroid, such as multiple organ failure, profound decrease in mentation and even death. We present a case of an 80-year-old female with a history of hypertension, coronary artery disease, chronic kidney disease, hypothyroidism due to total thyroidectomy, and a cerebral vascular accident who presented with slurred speech, decreased appetite, dizziness and lethargy with new-onset weakness. She was adherent to all her medications. Her labs were significant for elevated thyroid-stimulating hormone, elevated free thyroxine, and low total triiodothyronine. Brain MRI revealed no acute pathology. She was given her home dose of Levothyroxine and was admitted to the telemetry unit for evaluation of her symptoms and abnormal thyroid panel. During her hospital course, she was found to have an abnormal rhythm and worsening lethargy. Subsequent electrocardiogram and laboratory values revealed new T-wave inversions and elevated troponin. An echocardiogram revealed a new severely reduced left ventricular function with severe global hypokinesis of the left ventricle and an ejection fraction of 30%. It was only after initiating combination therapy of levothyroxine and liothyronine that her symptoms and abnormal cardiac rhythm resolved. With this careful titration of the patient's medication, we concluded that combination therapy was essential to the patient being euthyroid. This phenomenon was also cited in multiple literature, which warrants an investigation of a certain population's inability to convert T4 to T3. By sharing this case, we aim to aid providers with their differential diagnoses and bring to light a potential area of further investigation. Ultimately, by optimizing and tailoring these medications, we hope to improve their quality of life.