NGAL distinguishes steroid sensitivity in idiopathic nephrotic syndrome.
BACKGROUND
Idiopathic nephrotic syndrome (NS) is the most common glomerular disorder of childhood. Invasive biopsy remains the diagnostic method of choice for NS. Prognosis correlates with steroid responsiveness, from sensitive (SSNS) to resistant (SRNS). Neutrophil gelatinase-associated lipocalin (NGAL) has been demonstrated to be a powerful risk marker of chronic kidney disease progression. We set out to determine if urine NGAL can distinguish between patients with SRNS, SSNS, and healthy controls.


METHODS
Urine and clinical data were collected from patients at Cincinnati Children's Hospital who were recently diagnosed with active nephrotic syndrome as well as healthy controls. Participants included SRNS (n = 15), SSNS (n = 14), and healthy controls (n = 10). Urinary NGAL was measured by ELISA and normalized to creatinine.


RESULTS
Median NGAL was significantly (p < 0.001) higher in SRNS (172.3 ng/ml, IQR 18.8-789) than both SSNS (6.3 ng/ml, IQR 4.9-9.9) and healthy controls (6.5 ng/ml, IQR 4.2-9.1). The area under the curve (AUC) for NGAL to distinguish SRNS from SSNS was 0.91 (p < 0.0001). NGAL levels demonstrated a significant negative correlation with glomerular filtration rate (r = -0.5, p < 0.001). Results did not change with NGAL corrected for urine creatinine and were independent of the degree of proteinuria.


CONCLUSIONS
NGAL levels differentiate SSNS from SRNS and correlate with disease severity in SRNS.
Division Nephrology and Hypertension, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, ML 7022, Cincinnati, OH 45229, USA. michael.bennett@cchmc.org
Michael R
MR
Bennett
Nuntawan
N
Piyaphanee
Kimberly
K
Czech
Mark
M
Mitsnefes
Prasad
P
Devarajan
D000209:Acute-Phase Proteins / Q000652:urine*; D000293:Adolescent; D019540:Area Under Curve; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000652:urine; D003430:Cross-Sectional Studies; D003937:Diagnosis, Differential; D004351:Drug Resistance; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use; D007677:Kidney Function Tests; D000071068:Lipocalin-2; D054834:Lipocalins / Q000652:urine*; D008297:Male; D009404:Nephrotic Syndrome / Q000188:drug therapy* / Q000652:urine*; D011518:Proto-Oncogene Proteins / Q000652:urine*; D012959:Socioeconomic Factors; D013256:Steroids / Q000627:therapeutic use*; D055815:Young Adult
D000209:Acute-Phase Proteins; D007166:Immunosuppressive Agents; C489506:LCN2 protein, human; D000071068:Lipocalin-2; D054834:Lipocalins; D011518:Proto-Oncogene Proteins; D013256:Steroids; D003404:Creatinine