Detection of an earlier tubulopathy in diabetic nephropathy among children with normoalbuminuria.

Introduction: Diabetic nephropathy is a major cause of morbidity and mortality among young adults with type 1 diabetes mellitus (DM). Albuminuria, the gold standard for early diagnosis, cannot always detect early diabetic nephropathy. We aimed at evaluating the level of urine neutrophil gelatinase-associated lipocalin (NGAL) as a marker of tubulointerstitial damage in children and adolescents with type 1 DM in relation to the level of albuminuria and other parameters.

Materials And Methods: Fifty children with type 1 DM for more than 5 years were included in this study (mean age, 13.8 ± 4.0 years), and 18 healthy children served as controls. Patients with overt albuminuria (> 300 mg/g creatinine) or inflammatory states were excluded. Urine NGAL, microalbuminuria, and urine albumin-creatinine ratio were measured in patients and controls as well as other parameters.

Results: Urine NGAL was significantly higher in microalbuminuric in comparison with normoalbuminuric patients and controls, and correlated positively with urine albumin-creatinine ratio. A positive urine NGAL was observed in 12 of 38 normoalbuminuric patients (31.6%) compared to 9 of 12 microalbuminuric patients (75%). A positive correlation was reported between urine NGAL and both Hemoglobin A1c and duration of DM, but not with estimated glomerular filtration rate or hypertension.

Conclusions: Diabetic children, even some normoalbuminurics, showed increased urine NGAL. This finding may support the hypothesis of a "tubular phase" of diabetic disease preceding overt diabetic nephropathy, and hence, the use of urine NGAL measurement for early evaluation of renal involvement.