Urinary alkalinisation with oral sodium bicarbonate for patients at risk of contrast-induced nephropathy

Background: Intravenous sodium bicarbonate is used to reduce the risk of contrast-induced nephropathy (CIN). Intravenous sodium bicarbonate is inconvenient and requires inpatient hospital resources, while oral sodium bicarbonate is less costly and easy-to-use. Aim: To determine whether oral sodium bicarbonate has a similar effect on urinary pH as intravenous sodium bicarbonate in patients at risk of CIN. Method: This sequential crossover study was conducted in patients from the cardiology and renal units scheduled for a non-emergency contrast-enhanced procedure. Participants received intravenous sodium bicarbonate 150 mmol/L at 3 mL/ kg/h, 1 hour prior, then 1 mL/kg/h during and for 6 hours after the procedure. Participants returned to the hospital 2 to 3 weeks after their procedure to receive oral sodium bicarbonate capsules (16 x 840 mg, 160 mmol) over 7 hours with 1 L of water. Urinary pH was measured before and after the administration of intravenous and oral sodium bicarbonate. Results: 9 participants completed the study. Mean urinary pH after oral sodium bicarbonate was 6.6 (SD 0.6) versus 6.9 (SD 0.5) for intravenous sodium bicarbonate. The mean change in urinary pH was 0.9 (SD 0.7) with oral sodium bicarbonate versus 0.8 (SD 0.5) for intravenous sodium bicarbonate. The difference in change in urinary pH was not statistically significant (p = 0.5). Conclusion: Oral sodium bicarbonate has a similar effect on urinary pH as intravenous sodium bicarbonate in patients at risk of CIN.