Session: SAT 199-223-Disorders of Bone & Calcium Homeostasis: Case Reports
Poster Board SAT-214
Clinical case: A 58-year-old man presented with multiple thyroid nodules and enlarged cervical lymph nodes. Fine needle aspiration of the thyroid nodules was consistent with medullary thyroid carcinoma (MTC) and calcitonin level was elevated at 470 ng/L (<13.8). He underwent total thyroidectomy with central and left lateral lymph node dissection. Surgical pathology confirmed MTC. Both inferior parathyroids were removed during the surgery, which was also complicated by thoracic duct injury. On postoperative day 0, serum ionized calcium (iCa) level was 3.9 mg/dL (4.2-5.2) and parathyroid hormone (PTH) was undetectable <3pg/ml (11-80). After receiving 2 ampoules of intravenous (iv) calcium gluconate (186 mg of elemental calcium), he was started on oral calcium carbonate (CaCO3) 3 g, calcitriol 0.5 µg, and vitamin D3 1000 IU daily. Although iCa levels initially responded to oral therapy, on postoperative day 5, he developed symptoms of tetany (peri-oral numbness and Chvostek’s sign), confusion, and dysarthria. Serum iCa was 3.3 mg/dL. He was transferred to intensive care and started on a continuous iv calcium infusion. Oral treatment was titrated to CaCO3 4 g, calcitriol 4 µg, and vitamin D250,000 IU daily. Symptoms of tetany resolved as serum iCa improved but remained 3.7-4.2 mg/dL. In search for a cause of refractory hypocalcemia, it was noted that it was concurrent with a moderate output of chyle from the thoracic duct injury measuring 110 cc every 12 hours. Analysis of the chyle revealed a calcium concentration of 5.4 mg/dL (0.95-1.5). A medium chain fatty acid diet and subcutaneous octreotide were initiated with a subsequent decrease in chyle output and a rise in iCa level to 4.6 mg/dL. As chyle output decreased to <15 cc/day, iCa levels remained stable off of iv calcium.
Clinical lesson: Hypoparathyroidism and a chyle leak are potential complications following total thyroidectomy and left lateral lymph node dissection. This case of refractory hypocalcemia was attributed primarily to the chyle leak, which has an electrolyte composition similar to that of plasma. In patients with extensive neck dissection and chyle leak, calcium levels should be monitored and may need aggressive replacement to prevent hypocalcemia.
Nothing to Disclose: NA, AGP, MO, LC
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