title: Biochemical control of bone loss and stone-forming propensity by potassium-calcium citrate after bariatric surgery.
abstract: BACKGROUND
  Patients undergoing Roux-en-Y gastric bypass (RYGB) surgery are prone to developing bone loss and kidney stones. The goal of the present study was to test the hypothesis that an effervescent formulation of potassium calcium citrate (PCC) would avert metabolic complications by providing bioavailable calcium and alkali.
  
  
  METHODS
  A total of 24 patients with RYGB underwent a 2-phase crossover randomized trial comparing PCC and placebo. During the last 2 days of each 2-week phase, the serum and 24-hour urine samples were analyzed for calcium and bone turnover markers, acid base status, and urinary stone risk factors.
  
  
  RESULTS
  Compared with placebo, PCC marginally reduced the serum parathyroid hormone level and significantly decreased urinary deoxypyridinoline by 12% (P <.001) and serum type 1 collagen C-telopeptide by 22% (P <.01). PCC significantly increased the net gastrointestinal alkali absorption, citrate, and pH and significantly lowered the urinary net acid excretion (P <.001). The urinary saturation of uric acid decreased significantly (P <.001). The supersaturation of calcium oxalate and brushite did not change despite an increase in calcium and pH. In untreated urine samples with citrate concentrations altered to mimic those of placebo and PCC, calcium oxalate agglomeration was significantly inhibited by PCC.
  
  
  CONCLUSIONS
  In RYGB patients, PCC supplementation inhibited bone resorption by providing bioavailable calcium, reduced the urinary saturation of uric acid, and increased the inhibitor activity against calcium oxalate agglomeration by providing alkali that increased urinary pH and citrate.
authors.affiliation: Center from Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical School, Dallas, Texas, USA. khashayar.sakhaee@utsouthwestern.edu
authors.forename: Khashayar
authors.initials: K
authors.lastname: Sakhaee
authors.forename: Carolyn
authors.initials: C
authors.lastname: Griffith
authors.forename: Charles Y C
authors.initials: CY
authors.lastname: Pak
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D001682:Biological Availability; D015415:Biomarkers / Q000032:analysis; D019355:Calcium Citrate / Q000627:therapeutic use*; D018592:Cross-Over Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D015390:Gastric Bypass; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007669:Kidney Calculi / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000601:surgery*; D010024:Osteoporosis / Q000517:prevention & control*; D010919:Placebos; D011183:Postoperative Complications / Q000517:prevention & control*; D019357:Potassium Citrate / Q000627:therapeutic use*; D012307:Risk Factors; D014527:Uric Acid / Q000652:urine
chemical_list: D015415:Biomarkers; D010919:Placebos; D014527:Uric Acid; D019357:Potassium Citrate; D019355:Calcium Citrate