SUN-492 Treatment of Uncontrolled Graves’ Disease Reveals Underlying Thyroiditis

Thyrotoxicosis is a life-threatening condition that may result from poor adherence to medical therapy. We describe the case of a patient with Graves’ disease and a history of medication non-compliance who presented with tachyarrhythmia and heart failure (HF). His protracted course after weeks of inpatient treatment with thionamides, iodine, resin and beta-blockers, was followed by a dramatic improvement within days of adding steroids, suggesting the presence of concurrent untreated thyroiditis. Case Description: A 38-year-old man with an 18-month history of known Graves’ disease presented to the endocrinology clinic requesting thyroidectomy. He complained of 3 weeks of worsening palpitations, shortness of breath, bilateral lower extremity edema, and frequent loose stools. History revealed frequent interruption of thionamide and recent discontinuation of propranolol due to patient’s perceived lack of improvement. Physical exam showed a thin male with a large goiter. He was in moderate distress due to tachypnea. He had atrial fibrillation with rapid ventricular rate (A Fib with RVR) but was not in pulmonary edema. Laboratories showed a suppressed TSH (<0.02 mIU/L [0.45 - 4.70 mIU/L]), a free T4 above the level of detection (>6.99 ng/dL [0.78 - 2.20 ng/dL], and a total T3 level of above 781 pg/mL (97.0 - 170.0 ng/dL). Methimazole 30 mg BID and propranolol 40 mg TID were started, followed within a few hours with potassium iodine (SSKI) 3 drops TID. Although the patient’s HF improved and there was down-trending of free T4, he continued to have A fib with RVR. SSKI and propranolol were increased; diltiazem 90 mg QID and cholestyramine 2g BID were later added. Despite aggressive treatment, the patient continued to have intermittent tachyarrhythmia, postponing his planned thyroidectomy for weeks. Dexamethasone 2mg Q8H was then started aiming to further decrease T4 to T3 conversion. Interestingly, within 48 hours of the start of steroid therapy, his free T4 level markedly decreased and was well within the normal range several days later when he underwent a successful thyroidectomy, with no further tachyarrhythmia recurrence. Discussion: Thyrotoxicosis is aggressively treated given its high mortality rate. Treatment algorithms guide physicians to categorize hyperthyroidism either as the type associated with increased hormone synthesis and secretion or that which results from increased hormone release due to gland destruction. This thought process may lead, as in our case, to a delay in appropriate therapy and an increased risk of disease complications. Furthermore, providers should not assume that the lack of treatment response in a patient with Graves’ disease is the result of medication non-adherence. The possibility of coexisting thyroiditis and the absence of a treatment regimen that effectively addresses both underlying processes may be the actual cause for the lack of clinical improvement.