Urinary low-molecular-weight protein excretion in pediatric idiopathic nephrotic syndrome

Pediatr Nephrol. 2013 Dec;28(12):2299-306. doi: 10.1007/s00467-013-2569-6. Epub 2013 Aug 15.

Abstract

Background: Minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) are the most common causes of idiopathic nephrotic syndrome (INS). We have evaluated the reliability of urinary neutrophil-gelatinase-associated lipocalin (uNGAL), urinary alpha1-microglobulin (uα1M) and urinary N-acetyl-beta-D-glucosaminidase (uβNAG) as markers for differentiating MCD from FSGS. We have also evaluated whether these proteins are associated to INS relapses or to glomerular filtration rate (GFR).

Methods: The patient cohort comprised 35 children with MCD and nine with FSGS; 19 healthy age-matched children were included in the study as controls. Of the 35 patients, 28 were in remission (21 MCD, 7 FSGS) and 16 were in relapse (14 MCD, 2 FSGS). The prognostic accuracies of these proteins were assessed by receiver operating characteristic (ROC) curve analyses.

Results: The level of uNGAL, indexed or not to urinary creatinine (uCreat), was significantly different between children with INS and healthy children (p = 0.02), between healthy children and those with FSGS (p = 0.007) and between children with MCD and those with FSGS (p = 0.01). It was not significantly correlated to proteinuria or GFR levels. The ROC curve analysis showed that a cut-off value of 17 ng/mg for the uNGAL/uCreat ratio could be used to distinguish MCD from FSGS with a sensitivity of 0.77 and specificity of 0.78. uβNAG was not significantly different in patients with MCD and those with FSGS (p = 0.86). Only uα1M, indexed or not to uCreat, was significantly (p < 0.001) higher for patients in relapse compared to those in remission.

Conclusions: Our results indicate that in our patient cohort uNGAL was a reliable biomarker for differentiating MCD from FSGS independently of proteinuria or GFR levels.

Publication types

  • Evaluation Study

MeSH terms

  • Acetylglucosaminidase / urine
  • Acute-Phase Proteins / urine*
  • Adolescent
  • Age Factors
  • Alpha-Globulins / urine
  • Biomarkers / urine
  • Case-Control Studies
  • Child
  • Child, Preschool
  • Creatinine / urine
  • Cross-Sectional Studies
  • Glomerular Filtration Rate
  • Glomerulosclerosis, Focal Segmental / complications*
  • Glomerulosclerosis, Focal Segmental / diagnosis
  • Glomerulosclerosis, Focal Segmental / physiopathology
  • Humans
  • Kidney / physiopathology
  • Lipocalin-2
  • Lipocalins / urine*
  • Molecular Weight
  • Nephrosis, Lipoid / complications*
  • Nephrosis, Lipoid / diagnosis
  • Nephrosis, Lipoid / physiopathology
  • Nephrotic Syndrome / diagnosis
  • Nephrotic Syndrome / etiology*
  • Nephrotic Syndrome / physiopathology
  • Predictive Value of Tests
  • Prospective Studies
  • Proteinuria / diagnosis
  • Proteinuria / etiology*
  • Proteinuria / physiopathology
  • Proto-Oncogene Proteins / urine*
  • ROC Curve
  • Recurrence

Substances

  • Acute-Phase Proteins
  • Alpha-Globulins
  • Biomarkers
  • LCN2 protein, human
  • Lipocalin-2
  • Lipocalins
  • Proto-Oncogene Proteins
  • alpha-1-microglobulin
  • Creatinine
  • Acetylglucosaminidase

Supplementary concepts

  • Nephrosis, congenital