title: Loose and frequent stools and PTH levels are positively correlated post-gastric bypass surgery due to less efficient intestinal calcium absorption.
abstract: BACKGROUND
  After Roux-en-Y gastric bypass, calcium and vitamin D deficiencies are frequently reported. In the presence of adequate vitamin D levels, calcium deficiency is caused by a lower efficacy of the intestinal calcium transport.
  
  
  OBJECTIVE
  To investigate whether the use of a simple clinical score quantifying bowel habits (fecal score [FS]) correlates with the degree of secondary hyperparathyroidism that arises to compensate for calcium deficiency postsurgery.
  
  
  METHODS
  Large peripheral hospital.
  
  
  METHODS
  Seventy-five patients supplemented with calcium and vitamin D were prospectively studied before and 6 and 12 months after Roux-en-Y gastric bypass. FS, calcium (mmol/L), phosphate (mmol/L), magnesium (mmol/L), vitamin D (nmol/L), and parathyroid hormone (PTH; pmol/L) were measured in each patient.
  
  
  RESULTS
  Mean body mass index was 44.7±5.4 kg/m2preoperatively and decreased to 34.3±5.0 kg/m2at 6 months and 30.8±4.8 kg/m2at 12 months, corresponding to a total weight loss of 23.2±5.9% and 30.9±8.3% respectively. There were no significant changes in serum calcium levels. Mean PTH levels rose from 3.5 pmol/L at baseline to 4.1 pmol/L at 6 months (P = .01) and to 4.9 pmol/L at 12 months (P<.001). Nine patients (12%) had increased PTH levels at 6 months, and 14 patients (19%) had increased PTH levels at 12 months. A significant positive correlation between FS and PTH at 12 months was found, which persisted after adjusting for vitamin D levels.
  
  
  CONCLUSIONS
  FS is positively correlated with secondary hyperparathyroidism using vitamin D-adjusted PTH levels as a biochemical marker. The present study in humans confirms the relation reported in animal studies. These results emphasize that managing stool habits are important after bariatric surgery.
authors.affiliation: Department of Bariatric Surgery, Rijnstate Hospital, Arnhem, The Netherlands. Electronic address: wschijns@rijnstate.nl.
authors.forename: Wendy
authors.initials: W
authors.lastname: Schijns
authors.affiliation: Department of Bariatric Surgery, Rijnstate Hospital, Arnhem, The Netherlands.
authors.forename: Edo O
authors.initials: EO
authors.lastname: Aarts
authors.affiliation: Department of Bariatric Surgery, Rijnstate Hospital, Arnhem, The Netherlands.
authors.forename: Frits J
authors.initials: FJ
authors.lastname: Berends
authors.affiliation: Department of Bariatric Surgery, Rijnstate Hospital, Arnhem, The Netherlands.
authors.forename: Ignace M C
authors.initials: IM
authors.lastname: Janssen
authors.affiliation: Department of Internal Medicine and Endocrinology, Reinier de Graaf Group of Hospitals, Delft, The Netherlands.
authors.forename: Dave H
authors.initials: DH
authors.lastname: Schweitzer
mesh_terms: D002118:Calcium / Q000172:deficiency / Q000378:metabolism; D002119:Calcium Carbonate / Q000008:administration & dosage; D003672:Defecation / Q000502:physiology; D003967:Diarrhea / Q000209:etiology*; D019587:Dietary Supplements; D005260:Female; D015390:Gastric Bypass; D006801:Humans; D006962:Hyperparathyroidism, Secondary / Q000209:etiology*; D007408:Intestinal Absorption / Q000502:physiology; D008274:Magnesium / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000097:blood / Q000601:surgery; D010281:Parathyroid Hormone / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D011182:Postoperative Care; D011183:Postoperative Complications / Q000209:etiology; D011300:Preoperative Care; D011446:Prospective Studies; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000178:diet therapy
chemical_list: D010281:Parathyroid Hormone; D010710:Phosphates; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D002119:Calcium Carbonate; D008274:Magnesium; D002118:Calcium
keywords: Calcium; Fecal score; Roux-en-Y gastric bypass; Secondary hyperparathyroidism