Letters Section Editor: Robert M. Golub,
MD, Senior Editor.
In Reply: To Dr Shavit and colleagues, we state
that our primary end point was defined by percent change in serum creatinine.
Percent change in GFR was a secondary observation. As noted in our methods
section, we estimated the primary and secondary end points using the modified
rather than the original Levey formula.1 The
Modification of Diet in Renal Disease Study Group estimates GFR by multiplying:
186 × creatinine−1.154 × age−0.203. If the patient is African American, the product is multiplied by 1.21.
If the patient is female, the product is multiplied by 0.742. If the patient
is both African American and female, the product is multiplied by 1.21 and
0.742. This formula does not use serum albumin or BUN to calculate GFR. Thus,
better expansion of extracellular volume by NaHCO3 with subsequent
dilution of serum albumin or BUN can not account for our findings. Moreover,
previous investigators have reported that 500 mL of 0.154 mol/L NaCl actually
provides better volume expansion and renin suppression than 750 mL of 0.154
mol/L NaHCO3.2,3 We
did not collect serum albumin or BUN values as part of our study, and therefore
can not provide these data to Shavit et al, but we do not believe that differences
in volume expansion account for better protection from contrast-induced nephropathy
Burgess WP, Merten GJ, Kennedy TP. Prevention of Contrast-Induced Nephropathy With Sodium Bicarbonate—Reply. JAMA. 2004;292(12):1428-1429. doi:10.1001/jama.292.12.1428-c