Severe Symptomatic Hypocalcemia Following Total Thyroidectomy and Roux‐en‐Y Gastric Bypass

Patients who undergo Roux-en-Y gastric bypass (RYGB) procedures are at moderate risk for calcium and vitamin D deficiency. Those who subsequently undergo thyroid or parathyroid surgery are at high risk for developing severe symptomatic hypocalcemia if not monitored and prophylactically treated adequately. We present a morbidly obese patient who underwent Roux-en-Y gastric bypass six months prior to the discovery of metastatic papillary thyroid carcinoma. He subsequently underwent total thyroidectomy with central and bilateral neck dissection. Following surgery, he developed severe symptomatic hypocalcemia that reached a nadir of 6.0 mg/dL. He required aggressive oral and intravenous repletion therapy with calcium, vitamin D, and magnesium for ten days before hospital discharge. Providers should institute careful preoperative screening, patient counseling, and prophylactic calcium and vitamin D therapy for all RYGB patients who subsequently require thyroid surgery to prevent the development of severe and lifethreatening hypocalcemia. To date, only four reports have focused on the dangers of thyroid and parathyroid surgery in post gastric bypass surgery. We report this case to add to the growing body of literature for this patient population. CASE REPORT 40-year-old white male referred for evaluation of 5-cm neck mass, later determined to be metastatic papillary thyroid carcinoma 6 months prior, he had undergone RYGB for treatment of morbid obesity Preoperative calcium and TSH levels were within normal limits & preoperative medications included calcium citrate plus vitamin D He underwent total thyroidectomy with bilateral and central compartment lymph node excision, with autotransplantation of one parathyroid gland due to devascularization Following surgery, he was started on CaCO3 liquid suspension, elemental calcium, and cholecalciferol Over the first 24h his calcium dropped from 8.8 to 6.9 mg/dl and he remained asymptomatic. However, the following day he developed perioral numbness and a positive Chvostek’s sign, with calcium ranging from 6.7 to 7.3 mg/dl PICC access was obtained and he was treated symptomatically On POD 4, cholecalciferol was discontinued and ergocalciferol was started. CaCO3 was replaced with calcium citrate, HCTZ was initiated to decrease urinary calcium loss, and calcitriol was also started On POD 5-10, PTH increased from undetectable to 111 pg/mL, and calcium gradually improved from 6.6 to 8.3 mg/dL On POD ten, no signs or symptoms of hypocalcemia persisted, so the PICC line was removed and calcium citrate and ergocalciferol were continued PO Signs & symptoms of hypocalcemia were covered with the patient, and instructions were provided to return to the ED if symptoms returned At his three-week follow up appointment, calcium level was 8.2 mg/dL and he was experiencing no symptoms of hypocalcemia His current regimen includes ergocalciferol, calcium citrate, HCTZ, & calcitriol CONCLUSIONS  Patients undergoing thyroid or parathyroid surgery should be screened for a history of bariatric surgery. If positive, these patients should be counseled on the risk of developing severe hypocalcemia and pre-surgical prophylactic treatment with calcium and vitamin D should be instituted.  In the five reviewed reports of post-thyroidectomy hypocalcemia, all nine patients required intravenous calcium infusion to stabilize calcium levels. It follows, then, that precautionary PICC line placement should be acquired at the time of surgery for such patients.  Maximal replacement with oral calcium citrate, ergocalciferol, and calcitriol should be administered. We reserve intravenous calcium for symptomatic patients, in which case calcium gluconate should be considered.  Nursing staff should perform evaluations for symptomatic hypocalcemia q2h, including testing for Chvostek’s and Trousseau’s signs, as well as questioning about perioral and limb paresthesias.  Although not studied in this population, intramuscular teriparatide (recombinant PTH) injection may prove to be a useful drug in shortening hospital stay, and should be studied in the future.