Study of serum Neprilysin level in chronic kidney disease patients

Chronic kidney disease (CKD) is defined by a gradual decline in the glomerular filtration rate (GFR) over time, progressing toward more advanced stages. The study aimed to investigate serum Neprilysin (NEP) levels in patients at different stages of CKD to evaluate its role in diagnosis and progression of CKD. A cross-sectional pilot, study included 75 CKD patients classified according to KDIGO into five stages (stages 1–5) and 20 healthy controls. Participants underwent clinical assessment, laboratory tests (complete blood count, blood urea, serum creatinine, urine albumin to creatinine ratio, liver function tests, blood glucose, HbA1c and lipid profile, estimation of GFR [eGFR]) and serum NEP measurement by ELISA. NEP levels were significantly elevated in CKD patients relative to the normal control group (p1 = 0.002, p2 and p5 < 0.001), also it was found increased in advanced than early stage of CKD with significant elevation in stages 3–5 than stage 1 (p7 = 0.009, p8 = 0,003, p9 = 0.005). It is directly correlated with blood urea, serum creatinine, and albumin creatinine ratio (ACR), and negatively correlated with hemoglobin (Hb), white blood cells, and eGFR. NEP differentiates normal individuals from stage 1 CKD patients at a cut-off of > 168.0 and distinguished between patients with eGFR < 60 and ≥ 60 at ˃248.5 with 80% accuracy. Serum NEP were significantly higher in patients with CKD compared with controls and were associated with markers of renal dysfunction so, it could be a complementary biomarker in CKD. However, stage-wise differences should be interpreted cautiously after correction for multiple comparisons.