Superior calcium bioavailability of effervescent potassium calcium citrate over tablet formulation of calcium citrate after Roux-en-Y gastric bypass

Background: Calcium supplementation is commonly recommended for patients after Roux-en-Y gastric bypass to avert bone loss. To test the hypothesis that effervescent (liquid) potassium-calcium-citrate (PCC) might be more bioavailable than a tablet formulation of calcium citrate (Citracal Petite), the present study compared a single dose response of the 2 compounds. The present study was conducted at the University of Texas Southwestern Medical School at Dallas. Methods: A total of 15 patients who had undergone Roux-en-Y gastric bypass were included in a 2-phase, crossover, randomized study comparing the single-dose bioavailability of PCC versus Citracal Petite. After following a restricted diet for 1 week, the participants ingested either a single dose of 400 mg elemental calcium as PCC or Citracal Petite. Sequential serum and urine samples were collected for a 6-hour period after the dose and analyzed for calcium, parathyroid hormone, and acid-base parameters. Results: Compared with citracal petite, PCC significantly increased the serum calcium concentrations at 2, 3, and 4 hours after the oral load. The peak to baseline variation and increment in serum calcium (area under the curve) were significantly greater after PCC (P =.015 and P =.002, respectively). Concurrently, the baseline to nadir variation and decrement in serum parathyroid hormone (area over the curve) were significantly greater after PCC (P =.004 and P =.005, respectively). Moreover, compared with Citracal Petite, PCC caused a significantly greater increment in urinary citrate (P <.0001) and potassium (P =.0004) and a significantly lower increase in urinary ammonium (P =.045). Conclusion: In patients who have undergone Roux-en-Y gastric bypass, PCC was superior to Citracal Petite in conferring bioavailable calcium and suppressing parathyroid hormone secretion. PCC also provided an alkali load.