Urinary neutrophil gelatinase-associated lipocalin (NGAL) as a marker of diabetic nephropathy in type 1 diabetic patients

Abstract

Background: Glomerular and tubulointerstitial damage plays a role in renal function failure in diabetic patients. While both serum and urine levels of neutrophil gelatinase-associated lipocalin (NGAL) show significantly increased levels in acute renal pathologies, the NGAL increase in active phase indicates a reversible condition in chronic cases.

Materials and methods: 52 type 1 diabetic patients and 30 healthy volunteers participated in the study. The diabetic participants were separated into two groups as follows: a normoalbuminuria group consisting of those with an albumin/creatinine ratio less than 30 mg/g and an albuminuria group consisting of those with an albumin/creatinine ratio equal or greater than 30 mg/g. Albumin, creatinine and NGAL were measured in all participants.

Results: Urinary NGAL median level was 21.1 ng/mL for diabetic patients and 11.9 ng/mL for healthy controls, and the difference between the two groups was statistically significant. When diabetic patients were compared as those with and without albuminuria, the median urinary NGAL levels of normoalbuminuria and albuminuria were 24.7 and 16.1 ng/mL, respectively, but the difference was not statistically significant. Statistically similar results were obtained through evaluation of the ratio of urinary NGAL excretion to creatinine excretion. The NGAL/Cr ratio was significantly higher in diabetic patients than in healthy controls, but no statistically significant difference was found between the diabetic patients with and without albuminuria.

Conclusions: Urinary NGAL excretion in type 1 diabetic patients is found to be increased over a wide range, but it does not correlate with urinary albumin excretion. In this regard, urinary NGAL excretion should not be used as an alternative to microalbuminuria in detecting diabetic nephropathy. The greater amount of NGAL excretion among diabetic patients may be due to diabetic nephropathy with possible tubulointerstitial damage pathologies.