title: Hypoparathyroidism after total thyroidectomy in patients with previous gastric bypass.
abstract: OBJECTIVE
  Case reports suggest that patients with previous gastric bypass have an increased risk of severe hypocalcemia after total thyroidectomy, but there are no population-based studies. The prevalence of gastric bypass before thyroidectomy and the risk of hypocalcemia after thyroidectomy in patients with previous gastric bypass were investigated.
  
  
  METHODS
  By cross-linking The Scandinavian Quality Registry for Thyroid, Parathyroid and Adrenal Surgery with the Scandinavian Obesity Surgery Registry patients operated with total thyroidectomy without concurrent or previous surgery for hyperparathyroidism were identified and grouped according to previous gastric bypass. The risk of treatment with intravenous calcium during hospital stay, and with oral calcium and vitamin D at 6 weeks and 6 months postoperatively was calculated by using multiple logistic regression in the overall cohort and in a 1:1 nested case-control analysis.
  
  
  RESULTS
  We identified 6115 patients treated with total thyroidectomy. Out of these, 25 (0.4 %) had undergone previous gastric bypass surgery. In logistic regression, previous gastric bypass was not associated with treatment with i.v. calcium (OR 2.05, 95 % CI 0.48-8.74), or calcium and/or vitamin D at 6 weeks (1.14 (0.39-3.35), 1.31 (0.39-4.42)) or 6 months after total thyroidectomy (1.71 (0.40-7.32), 2.28 (0.53-9.75)). In the nested case-control analysis, rates of treatment for hypocalcemia were similar in patients with and without previous gastric bypass.
  
  
  CONCLUSIONS
  Previous gastric bypass surgery was infrequent in patients undergoing total thyroidectomy and was not associated with an increased risk of postoperative hypocalcemia.
authors: Sten Tibblin Fellow, Dept. of Surgery, Skane University Hospital, Lund, Sweden.
authors: Raoul A
authors: RA
authors: Droeser
authors: Dept. of Surgery, Faculty of Medicine and Health, Örebro University, Örebro, Sweden.
authors: Johan
authors: J
authors: Ottosson
authors: Dept. of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors: Andreas
authors: A
authors: Muth
authors: Dept. of Surgery, Akademiska Hospital, Uppsala, Sweden.
authors: Hella
authors: H
authors: Hultin
authors: Dept. of Surgery, Gävle County Hospital, Gävle, Sweden.
authors: Karin
authors: K
authors: Lindwall-Åhlander
authors: Dept. of Surgery, Skane University Hospital, S-221 85, Lund, Sweden.
authors: Anders
authors: A
authors: Bergenfelz
authors: Dept. of Surgery, Skane University Hospital, S-221 85, Lund, Sweden. martin.almquist@med.lu.se.|Lund University, S-221 85, Lund, Sweden. martin.almquist@med.lu.se.
authors: Martin
authors: M
authors: Almquist
mesh_terms: D000328:Adult; D005260:Female; D015390:Gastric Bypass; D006801:Humans; D006996:Hypocalcemia / Q000453:epidemiology*; D007011:Hypoparathyroidism / Q000453:epidemiology*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology*; D012042:Registries; D012189:Retrospective Studies; D013959:Thyroid Diseases / Q000473:pathology / Q000601:surgery*; D013965:Thyroidectomy / Q000009:adverse effects*
keywords: Cohort study; Gastric bypass; Postoperative hypoparathyroidism; Total thyroidectomy