Brief Article
Copyright ©2009 The WJG Press and Baishideng. All rights reserved.
World J Gastroenterol. Dec 21, 2009; 15(47): 5960-5965
Published online Dec 21, 2009. doi: 10.3748/wjg.15.5960
Hyperphosphatemia after sodium phosphate laxatives in low risk patients: Prospective study
Marcela Noemi Casais, Guillermo Rosa-Diez, Susana Pérez, Elina Noemi Mansilla, Susana Bravo, Francisco Carlos Bonofiglio
Marcela Noemi Casais, Susana Pérez, Elina Noemi Mansilla, Susana Bravo, Francisco Carlos Bonofiglio, Department of Anesthesia, Preoperative Evaluation Section, Hospital Italiano de Buenos Aires, Rivadavia 4965, 9C, Buenos Aires, Argentina
Guillermo Rosa-Diez, Department of Nephrology, Preoperative Evaluation Section, Hospital Italiano de Buenos Aires, Rivadavia 4965, 9C, Buenos Aires, Argentina
Author contributions: Casais MN, Pérez S and Bonofiglio FC designed the research; Casais MN, Mansilla EN and Bravo S performed the research; Rosa-Diez G, Pérez S and Casais MN analyzed the data; Casais MN wrote the paper; Bonofiglio FC and Rosa-Diez G critically revised the paper.
Correspondence to: Marcela Noemi Casais, MD, Department of Anesthesia, Preoperative Evaluation Section, Hospital Italiano de Buenos Aires, Rivadavia 4965, 9C, Buenos Aires, Argentina. marcela.casais@hospitalitaliano.org.ar
Telephone: +54-11-49018829 Fax: +54-11-49018829
Received: July 13, 2009
Revised: August 7, 2009
Accepted: August 14, 2009
Published online: December 21, 2009
Abstract

AIM: To establish the frequency of hyperphosphatemia following the administration of sodium phosphate laxatives in low-risk patients.

METHODS: One hundred consecutive ASA I-II individuals aged 35-74 years, who were undergoing colonic cleansing with oral sodium phosphate (OSP) before colonoscopy were recruited for this prospective study. Exclusion criteria: congestive heart failure, chronic kidney disease, diabetes, liver cirrhosis, intestinal obstruction, decreased bowel motility, increased bowel permeability, and hyperparathyroidism. The day before colonoscopy, all the participants entered a 24-h period of diet that consisted of 4 L of clear fluids with sugar or honey and 90 mL (60 g) of OSP in two 45-mL doses, 5 h apart. Serum phosphate was measured before and after the administration of the laxative.

RESULTS: The main demographic data (mean ± SD) were: age, 58.9 ± 8.4 years; height, 163.8 ± 8.6 cm; weight, 71 ± 13 kg; body mass index, 26 ± 4; women, 66%. Serum phosphate increased from 3.74 ± 0.56 to 5.58 ± 1.1 mg/dL, which surpassed the normal value (2.5-4.5 mg/dL) in 87% of the patients. The highest serum phosphate was 9.6 mg/dL. Urea and creatinine remained within normal limits. Post-treatment OSP serum phosphate concentration correlated inversely with glomerular filtration rate (P < 0.007, R2 = 0.0755), total body water (P < 0.001, R2 = 0.156) and weight (P < 0.013, R2 = 0.0635).

CONCLUSION: In low-risk, well-hydrated patients, the standard dose of OSP-laxative-induced hyperphosphatemia is related to body weight.

Keywords: Bowel preparation; Colonic cleansing; Colonoscopy; Hyperphosphatemia; Laxatives; Sodium phosphate; Preoperative evaluation; Dehydration