Urinary levels of podocalyxin as a marker for podocytopathy in patients with metabolic syndrome having high body mass index: a diagnostic test accuracy study

Abstract

Aim To assess the adequacy of urinary podocalyxin (PCX) as a biomarker for early detection and disease progression of podocytopathy in high-BMI patients with metabolic syndrome with normal and impaired kidney functions. Patients and methods This is a cross-sectional study where all participants were subjected to full history taking, complete physical examination with assessment of BMI, and laboratory investigation to assess the inclusion and exclusion criteria. Then, a fresh morning urinary sample was obtained to measure both urinary albumin/creatinine ratio (UACR) and urinary PCX, where urinary PCX is measured by using human PCX ELISA kit. Results Urinary PCX showed that it can differentiate between group BI (albuminuric with normal renal functions) and BII (impaired renal functions) at the suggested cutoff point of 285 pg/ml, with 52% sensitivity and 45% specificity with low positive predictive value 48.8% and negative predictive value 48.6% by using receiver operating characteristic analysis, with P value 0.008, but it cannot differentiate between group A (completely normal renal functions) and neither of group BI nor BII. Conclusion Although urinary PCX is more sensitive for the diagnosis of early diabetic nephropathy than UACR and is used as a marker of chronic kidney disease progression in diabetic patients, UACR is still the gold standard for diagnosis and follow-up of diabetic nephropathy. Urinary PCX is nonspecific and cannot be related to BMI in patients with metabolic syndrome.