The significance of elevated levels of parathyroid hormone in patients with morbid obesity before and after bariatric surgery

Abstract

Hypothesis The risk of hyperparathyroidism after the duodenal switch operation is related to the length of the common channel. Design A retrospective analysis of patients following the duodenal switch operation from october 2, 2000, through february 1, 2002. Setting Academic tertiary referral hospital. Patients One hundred sixty-five consecutive patients underwent the duodenal switch operation, performed for morbid obesity, with common channel lengths of 75 cm (n = 103 [group a]) and 100 cm (n = 62 [group b]). Main outcome measures Weight loss and parathyroid hormone, corrected calcium, and 25-hydroxyvitamin d (25-oh d) levels were compared between groups a and b. values were determined preoperatively, early postoperatively (3-6 months), and late postoperatively (9-18 months). Results Both groups exhibited a slight reduction in serum calcium concentration, with one quarter decreasing below the normal range. hyperparathyroidism was more common in group a than group b preoperatively (38.9% vs 14.9%), reflecting the higher body mass index of patients in group a. hyperparathyroidism was also more frequent in the early (54.9% vs 30.9%) and late (49.4% vs 20.5%) postoperative periods in group a vs group b. new-onset hyperparathyroidism was also more common in group a than group b (42.0% vs 13.3%). after 1 year, subnormal 25-oh d levels were found in 17.0% of the patients in group a and in 10.0% of the patients in group b. median 25-oh d levels increased in both groups, but tended to be higher in group b. Conclusions Patients with shorter common channels had a higher risk of developing hyperparathyroidism. this may be related to limited 25-oh d absorption.