To assess the renal safety of sodium phosphate used as a boost in colon capsule endoscopy by comparing pre- and post-procedure renal function and electrolytes

We performed a retrospective observational study including consecutive adult patients who underwent colon capsule endoscopy with sodium phosphate used as a boost regimen at a single tertiary care center. Patients were eligible if serum creatinine, estimated glomerular filtration rate (eGFR), sodium and potassium were available within 7 days before and within 1 days after the procedure. Continuous variables were compared using paired statistical tests as appropriate, and statistical significance was set at p < 0.05.

A total of 76 patients were included in the analysis. Mean age was 73 years (SD 16 years). Paired pre–post comparisons showed no significant changes in renal function after sodium phosphate administration. Serum creatinine remained stable (p=0.174), and estimated glomerular filtration rate (eGFR) also showed no significant variation (p=0.111).

Blood urea levels significantly decreased after the procedure (p<0.001), a finding consistent with hemodilution rather than renal impairment.

Electrolyte levels remained largely unchanged. Serum sodium showed no significant pre–post difference (p=0.151). Serum potassium demonstrated a statistically significant decrease (p<0.001), although no clinically relevant hypokalemia was identified.

No patient met KDIGO criteria for acute kidney injury.

Sodium phosphate used as a boost for colon capsule endoscopy was not associated with renal function deterioration. Both creatinine and eGFR remained stable after the procedure, and the observed decrease in blood urea was consistent with hemodilution rather than kidney injury. Electrolyte levels were largely unchanged, and the reduction in serum potassium, although statistically significant, had no clinical relevance. No cases of acute kidney injury were identified.These findings support the renal and metabolic safety of sodium phosphate in this setting.