Influence of renal function on serum and urinary heart fatty acid-binding protein levels

Serum heart fatty acid-binding protein (H-FABP) has been reported to be a sensitive and early indicator of myocardial damage. However, circulating H-FABP may be cleared considerably from kidney, similar to that found for myoglobin. Therefore, the possibility exists that any change in renal function affects serum H-FABP concentration, and thus leads to erroneous interpretation. To evaluate the influence of renal function on H-FABP levels, we conducted a prospective study.

Nineteen patients undergoing isolated primary coronary artery bypass grafting were enrolled in this study. The patients were classified by the preoperative creatinine clearance into two groups: the control group (n=12); patients with creatinine clearance of 40 mL/min or greater, and the renal dysfunction group (n=7); patients with creatinine clearance of less than 40 mL/min. Serum H-FABP, CK-MB, troponin-T and urinary H-FABP levels were measured perioperatively.

None of the patients had perioperative myocardial infarction. No significant differences were found in CK-MB and troponin-T levels between the groups. The renal dysfunction group resulted in significantly (p<0.05) higher serum H-FABP levels and lower urinary H-FABP levels than those in the control group, postoperatively. The creatinine clearance correlated inversely with the peak levels of serum H-FABP (r=-0.75, p=0.0001) and correlated with the peak levels of urinary H-FABP (r=0.64, p=0.003).

The results indicate that the kidneys play an important role in the clearance of serum H-FABP. Thus, caution must be taken in interpreting this marker for myocardial damage during cardiac surgery in patients with renal dysfunction.