SAT-319 - Rapid Perioperative Management of Thyrotoxicosis for Urgent Nonthyroid Surgery

Background
The optimal perioperative management for the thyrotoxic patient pending urgent nonthyroidal surgery is not known.

Clinical Case
Here we describe a 57-year-old female with recently diagnosed Grave’s disease who was found to have a right-sided 26 cm liposarcoma with mass effect on the inferior vena cava (IVC), ureter, and intestines. She started methimazole 10mg daily a few weeks prior, but preoperative labs revealed thyroid stimulating hormone (TSH) of < 0.01 (0.27-4.20 ulU/mL), free triiodothyronine (FT3) of 21.1 (2.5-4.3 pg/mL), and free thyroxine (FT4) of 5.61 (0.92-1.68 ng/dL). She was clinically asymptomatic. Surgery was planned within 5 days. Methimazole 40mg three times a day (TID), propranolol 40mg TID, SSKI 250mg TID, prednisone 40mg TID, and cholestyramine 4g four times a day was initiated. On the day of operation, thyroid labs were improving with FT3 6.2 pg/mL and FT4 4.39 ng/dL. The patient underwent en bloc resection of the liposarcoma and right nephrectomy, with 2 liters blood loss. Post-operatively, she was hypertensive requiring nicardipine and esmolol drips with a low-grade temperature of 38C, but there was no evidence of thyroid storm. Her antithyroid drug (ATD) regimen was tapered over a few days. On discharge, FT3 was 3.5 pg/mL and FT4 was 3.52 ng/dL, and she was continued on methimazole 30mg daily and propanolol 20mg TID as needed.

Discussion
Thyroid storm is a feared complication for thyrotoxic patients undergoing surgery. Guidelines recommend patients be euthyroid on thionamides before surgery. SSKI is generally recommended preoperatively for thyroidectomy. However, the optimal preoperative regimen for the hyperthyroid patient pending time-critical non-thyroid surgery is controversial. There is limited data on the incidence of thyroid storm in such patients, with reports ranging from 0% to 14%. No current guidelines exist for pre-operative biochemical or clinical cut-offs. For our patient, due to the risk of rapid tumor growth and compression of the IVC, urgent surgery was necessary before a euthyroid state could be achieved. Our patient was treated using a multimodal approach with methimazole, beta blocker, SSKI, steroids, and cholestyramine. Similar protocols have been described to rapidly control thyrotoxicosis preoperatively. This case demonstrates the safety and efficacy of such protocols, with a clinically significant decrease in T3, as well as reduction in T4 levels, albeit at a slower rate, consistent with prior case reports. Some reports have described patients developing thyroid storm post-operatively, and signs of developing thyroid storm can be masked intraoperatively by anesthetics. Despite this, the rapidity with which ATDs can be tapered postoperatively is not well studied. Given our patient’s transient hypertension and elevated temperature, this case additionally highlights the importance of close post-operative monitoring.

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