Effect of N-acetylcysteine on serum creatinine and kidney function: results of a randomized controlled trial

Background: Evidence for a protective effect of N-acetylcysteine (NAC) on acute and chronic kidney disease is equivocal, and controversy persists about whether NAC affects creatinine level independently of actual kidney function. Study objectives are to investigate whether NAC affects serum creatinine level independently of alterations in other measures of kidney function.

Study design: Double-blind randomized controlled trial.

Setting & participants: Patients with stage 3 chronic kidney disease (n = 60), Canada, 2007-2008.

Intervention: Participants were randomly allocated to receive 4 doses of oral NAC (each 1,200 mg) or placebo, administered at 12-hour intervals.

Outcome: The primary outcome was change in serum creatinine level between baseline and 4 hours after the last treatment dose. In addition, changes in other parameters of kidney function were measured between baseline and 4, 24, or 48 hours after the last treatment dose.

Measurements: Serum creatinine, cystatin C, 24-hour urine protein and creatinine excretion, and creatinine clearance.

Results: 60 patients, mean age of 70 years, 75% men, 50% had diabetes, with mean creatinine clearance of 43.7 ± 18.8 (SD) mL/min were enrolled. Between baseline and 4 hours posttreatment, serum creatinine level decreased by 0.044 ± 0.15 mg/dL in the NAC group and 0.040 ± 0.18 mg/dL in the placebo group (95% CI for difference, -0.09 to 0.08; P = 0.9). No significant differences between groups were observed for change in serum creatinine, cystatin C, urine protein, urine creatinine, or creatinine clearance values at any time.

Limitations: Blinding patients to orally administered liquid NAC is difficult and it is possible that patients receiving NAC were not sufficiently blinded. Effects of NAC beyond 48 hours of treatment were not evaluated.

Conclusions: In this randomized controlled trial, NAC had no short-term effect on creatinine level and did not decrease urine protein excretion within 48 hours of treatment.