AIM:To investigate the changes in renal function at 12-24 mo in patients following sodium phosphate(NaP) preparation for screening colonoscopy.METHODS:We carried out a retrospective study on the results from patients who received health check-up services as part of an employer-provided wellness program performed between August 2006 and May 2008 and who were followed up for 12-24 mo.Prior to screening colonoscopy,224 patients underwent bowel cleansing with NaP(NaP group) and 113 patients with polyethylene glycol(PEG group).The control group comprised 672 age-matched patients.We compared the changes in the creatinine levels and the glomerular filtration rates(GFRs) from baseline to 12-24 mo between the NaP,PEG,and control groups using two-way repeated measured analysis of variance.In addition,multivariate linear regression analysis was performed to assess the risk factors for a decreased GFR.RESULTS:The baseline mean serum creatinine level in the NaP,PEG,and control groups was 1.12 ± 0.15,1.12 ± 0.16,and 1.12 ± 0.15 mg/dL,which increased to 1.15 ± 0.15,1.15 ± 0.18,and 1.15 ± 0.15 mg/dL,respectively,after 12-24 mo.The baseline mean GFR in the NaP,PEG,and control groups was 69.0 ± 7.7,68.9 ± 8.0,and 69.6 ± 6.7 mL/min per 1.73 m2,which decreased to 66.5 ± 7.8,66.5 ± 8.3,and 67.4 ± 6.4 mL/min per 1.73 m2,respectively,after 12-24 mo.The changes in serum creatinine levels and GFRs were not significantly between the NaP,PEG,and control groups(P = 0.992 and P = 0.233,respectively).Using multivariate linear regression analysis,only the baseline GFR was associated with the change in GFR(P < 0.001).Indeed,the bowel preparations were not associated with the change in GFR(P = 0.297).CONCLUSION:NaP bowel preparation in subjects with normal renal function was not associated with renal injury,and NaP can thus be used safely for screening colonoscopy. AIM: To investigate the changes in renal function at 12-24 mo in patients following sodium phosphate (NaP) preparation for screening colonoscopy. METHODS: We carried out a retrospective study on the results from patients who received health check-up services as part of an employer-provided wellness program performed between August 2006 and May 2008 and who were followed up for 12-24 mo. Prior to screening colonoscopy, 224 patients underwent bowel cleansing with NaP (NaP group) and 113 patients with polyethylene glycol (PEG group) The control group comprised 672 age-matched patients. We compared the changes in the creatinine levels and the glomerular filtration rates (GFRs) from baseline to 12-24 mo between the NaP, PEG, and control groups using two-way repeated measured analysis of variance. In addition, multivariate linear regression analysis was performed to assess the risk factors for a decreased GFR .RESULTS: The baseline mean serum creatinine level in the NaP, PEG, and control groups was 1.12 ± 0. 15,1.12 ± 0.16, and 1.12 ± 0.15 mg / dL, respectively, which increased to 1.15 ± 0.15, 1.15 ± 0.18, and 1.15 ± 0.15 mg / dL, respectively, after 12-24 mo. The baseline mean GFR in the NaP, PEG , and decreased to 66.5 ± 7.8, 66.5 ± 8.3, and 67.4 ± 6.4 mL / min per 1.73 m2, respectively, after 12 -24 mo.The changes in serum creatinine levels and GFRs were not significantly between the NaP, PEG, and control groups (P = 0.992 and P = 0.233, respectively). Using the multivariate linear regression analysis, only the baseline GFR was associated with the change in GFR (P <0.001) .Deed, the bowel preparations were not associated with the change in GFR (P = 0.297) .CONCLUSION: NaP bowel preparation in subjects with normal renal function was not associated with renal injury, and NaP is thus be used safely for screening colonoscopy.