NPPB and Nephropathy: Patients in group C with extremely elevated NT-proBNP have a higher risk of concomitant kidney damage, with a shorter survival time Moreover, LVEF was significantly lower in group C compared to groups A and B. In another study, Guglin et al. showed that there was no correlation between age, gender, and high NT-proBNP values (>4000 pg/mL, r = 0.29), but with a significant correlation with serum creatinine values (p < 0.0001).