Evaluation of children and adolescents with type 1 diabetes for early findings of renal injury: Can neutrophil gelatinase-associated lipocalin be a marker?

Objective: Biomarkers other than microalbuminuria are needed to detect early kidney injury in children with type 1 diabetes. Here, we aimed to determine the place of neutrophil-gelatinase associated lipocalin (NGAL) in detecting diabetic kidney injury in normoalbuminuric and normotensive adolescents with type 1 diabetes and to assess the relationship between NGAL and clinical and laboratory variables.Methods: Forty six adolescents with type 1 diabetes [M/F: 24/22; median age 14.5 years (12.2-16), diabetes duration 4.8 years (2.6-6.7), HbA1c 7.9% (7.2-9.2)] and 21 control cases [M/F: 7/14; median age 14.8 years (13.6-15.5)] were compared regarding clinical, laboratory (including urine and plasma NGAL), and ambulatory blood pressure monitoring (ABPM) variables. According to risk factors including high-normal albuminuria, long-term HbA1c>8.2%, diabetes duration ?5 years, hypertension detected by ABPM, and nondipping, type 1 diabetics were divided into subgroups allowing further assessment of association of NGAL levels with study variables.Results: Median blood and urine glucose, HbA1c, spot urine NGAL/creatinine ratio [13.2 (8.3-43.1) vs. 4.8 (2.9-20.2), p=0.015], and daytime systolic and diastolic blood pressure (BP) SD score and BP loads were found higher in diabetics. Urine NGAL levels were found to be correlated with albumin/creatinine ratio (r=0.452, p=0.002) while plasma NGAL levels were correlated with nighttime systolic BP load (r=0.309, p=0.037). Subgroup analyses showed similar NGAL levels except higher median urine NGAL levels [48.7 ng/mL (27.9-149.1) vs. 11.2 ng/mL (6-23.4), p=0.004] and urine NGAL/creatinine ratio [39.3 ng/mg (21.1-126.3) vs. 11.8 ng/mg (6.3-40.9), p=0.03] in diabetics with high-normal albuminuria (n=6) compared to those of patients with low-normal albuminuria (n=40).Conclusion: Urine NGAL levels indicate early kidney injury in normoalbuminuric and normotensive adolescents with type 1 diabetes. The importance of elevated NGAL levels needs to be evaluated for future development of diabetic complications.