Biomarkers of therapeutic response in primary nephrotic syndrome

Abstract

To the Editors,The recent retrospective study from Bennett et al. [1]inwhich they report thatmeasurementof urinary concentrationof NGAL (neutrophil gelatinase-associated lipocalin) ena-bles discrimination of children with steroid-responsive fromsteroid-resistant nephrotic syndrome is potentially of greatvalue in nephrology practice. In general, elevated urinaryexcretion of NGAL indicated the presence of steroid-resistant disease caused by biopsy-confirmed focal segmen-tal glomerulosclerosis (FSGS) in most of the cases. Theauthors claim that their findings represent the first descrip-tion of a simple urine test that could differentiate betweenthese two clinical categories of glomerular disease. Howev-er, over 15 years ago, we described significantly higherurinary nitrite excretion in children with presumed minimalchange nephrotic syndrome (MCNS) (n048) compared tochildren with FSGS (n010) [2]. The higher levels of nitritein the urine were documented in children with MCNSregardless of whether they were in remission or relapse(n010) and were unaffected by concomitant therapy withcorticosteroids or diuretics. These observations suggest thatthere are probably several urinary biomarkers that mayenable distinction between steroid-responsive and steroid-resistant disease in children with new-onset nephrotic syn-drome. No single biomarker is likely to be totally effectivein all patient groups.However, following the lead of Devarajan and others [3]who have pioneered the use of urinary biomarkers in thediagnosis of acute kidney injury, I would suggest that inves-tigators work together to develop a panel of suitable bio-markers that can be combined in an array and testedsimultaneously in a single assay to enhance the sensitivityand specificity of these analytes in patients with new-onsetprimary nephrotic syndrome. Such an approach would be awelcome addition to the management of children and ado-lescents with this important clinical problem.References