Comparison of the absorption of calcium carbonate and calcium citrate after Roux-en-Y gastric bypass.
BACKGROUND
Roux-en-Y gastric bypass (RYGB) restricts food intake. Consequently, patients consume less calcium. In addition, food no longer passes through the duodenum, the main site of calcium absorption. Therefore, calcium absorption is significantly impaired. The goal of this study is to compare two common calcium supplements in gastric bypass patients.


METHODS
Nineteen patients were enrolled in a randomized, double-blinded, crossover study comparing the absorption of calcium from calcium carbonate and calcium citrate salts. Serum and urine calcium levels were assessed for peak values (C (max)) and cumulative calcium increment (area under the curve [AUC]). Serum PTH was assessed for minimum values (PTH(min)) and cumulative PTH decrement (AUC). Statistical analysis was performed using a repeated analysis of variance model.


RESULTS
Eighteen subjects completed the study. Calcium citrate resulted in a significantly higher serum C (max) (9.4 + 0.4 mg/dl vs. 9.2 + 0.3 mg/dl, p = 0.02) and serum AUC (55 + 2 mg/dl vs. 54 + 2 mg/dl, p = 0.02). Calcium citrate resulted in a significantly lower PTH(min) (24 + 11 pg/ml vs. 30 + 13 pg/ml, p = 0.01) and a higher AUC (-32 + 51 pg/ml vs. -3 + 56 pg/ml, p = 0.04). There was a non-significant trend for higher urinary AUC in the calcium citrate group (76.13 + 36.39 mg/6 h vs. 66.04 + 40.82, p = 0.17).


CONCLUSIONS
Calcium citrate has superior bioavailability than calcium carbonate in RYGB patients.
Department of Internal Medicine, Charles and Jane Pak Center for Mineral Metabolism, UT Southwestern Medical Center, Dallas, TX 75390-8885, USA.
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P
Tondapu
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D
Provost
B
B
Adams-Huet
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T
Sims
C
C
Chang
K
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Sakhaee
D000328:Adult; D019540:Area Under Curve; D002119:Calcium Carbonate / Q000493:pharmacokinetics*; D019355:Calcium Citrate / Q000493:pharmacokinetics*; D018592:Cross-Over Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D015390:Gastric Bypass; D006801:Humans; D007408:Intestinal Absorption; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000378:metabolism* / Q000601:surgery*; D010281:Parathyroid Hormone / Q000097:blood
D010281:Parathyroid Hormone; D002119:Calcium Carbonate; D019355:Calcium Citrate