NPPB and Abnormal renal physiology: Furthermore, peak VO2 was reduced with renal dysfunction (eGFR ≤60 ml/min) (r2 = 0.27; p<0.001), increased BNP or NT-proBNP levels (r2 = 0.14; p = 0.014), or reduced hemoglobin concentration (r2 = 0.14; p = 0.017).