Primary Hyperparathyroidism After Roux-en-Y Gastric Bypass

Primary hyperparathyroidism (PHPT) in the setting of previous roux-en-Y gastric bypass (RYGBP) is not well described. The diagnosis can be difficult, as secondary hyperparathyroidism (SHPT) commonly occurs in patients after RYGBP due to calcium malabsorption and vitamin D deficiency.

All patients from 2000 to 2012 who underwent cervical exploration for diagnosis of primary hyperparathyroidism with history of preceding RYGBP were identified and analyzed retrospectively.

Ten patients were identified. The average age was 58.4 and all patients were female. Time interval between RYGBP and cervical exploration was 67 months with median follow-up of 19 months. Average preoperative calcium was 10.8 mg/dL, PTH 155 pg/mL, and 25-vitamin-D 32 ng/mL. Eighty percent of patients presented with symptoms and 90 % underwent preoperative imaging. Seventy percent underwent initial focused parathyroidectomy with 20 % being converted to four-gland exploration. Seventy percent of patients had a single adenoma with two patients having multi-gland disease. Intraoperative PTH was used in seven patients with successful drop to 50 % of baseline in all. Ninety percent of patients had greater then 6-month follow-up without evidence of persistent or recurrent PHPT. Average 6-month calcium was 9.3 mg/dL, PTH 73 pg/mL, and 25-vitamin-D 44 ng/ML. Four patients had evidence of persistently elevated PTH despite normalization of calcium.

PHPT after RYGBP is rare but surgery with either a focused approach following successful localization or four-gland exploration is indicated when the biochemical diagnosis holds true. The presence of SHPT can make diagnosis and follow-up difficult and may predispose them to severe post-operative hypocalcemia.