RESUMO
The objective of this study was to determine the diagnostic cutoff value of N-terminal-pro B-type natriuretic peptide (NT-pro BNP) as a marker of left ventricular (LV) dysfunction in children with end-stage renal disease (ESRD) on regular hemodialysis (HD). The study was carried out on thirty children with ESRD on regular HD and thirty healthy controls. Echocardiographic studies were done, including a conventional mode for ejection fraction, fractional shortening, tissue Doppler imaging, and longitudinal global strain by speckle tracking. Serum levels of NT-pro BNP were measured in venous blood samples before and about 30 min after HD by ELISA. Volume status was assessed by calculating interdialytic weight gain %. There were significant higher serum NT-pro BNP levels before HD (mean: 702.3 ± 274.3 ng/L) compared to controls (mean: 365.55 ± 76.5 ng/L) (P <0.001) and these levels decreased significantly after the HD session (mean: 625.1 ± 117.69 ng/L) (P = 0.031). Echocardiographic studies showed a significant impairment of LV function of the patients compared to controls. Patients with LV dysfunction had significant higher serum concentrations of NT-pro BNP compared to patients without dysfunction both before (P = 0.003) and after dialysis (P <0.001). Receiver operating curve demonstrated better prediction of LV dysfunction by NT-pro BNP levels after HD compared to its levels before HD (area under the curve was 0.9 and 0.73, respectively). Using a cutoff value of 630 ng/L, serum NT-pro BNP levels after dialysis were a diagnostic predictor of LV dysfunction with a sensitivity of 86.6%, specificity of 93.3%, positive predictive value of 92.8%, and negative predictive value of 87.5%. Serum NT-pro BNP levels were strongly correlated with the parameters of LV dysfunction in children with ESRD on regular HD. A postdialysis cutoff value of 630 ng/L could serve as a biochemical marker of LV dysfunction in those children regardless of chronic fluid overload.
