Tubular markers are associated with decline in kidney function in proteinuric type 2 diabetic patients

Our aim was to investigate u-NGAL, u-KIM1 and p-FGF23 and prediction of decline in kidney function in type 2 diabetic patients with proteinuria.

We performed a follow-up study, follow-up median (range) 3.5 (1-5) years. At baseline u-NGAL, u-KIM1 and p-FGF23 (ELISA) was measured and patients were followed yearly with estimated(e)-GFR (MDRD) and u-albumin.

We included 177 patients (44 women), mean age (SD) 59 (9) years. eGFR 90 (24) ml/min/1.73 m(2) at baseline, u-albumin: median (interquartile range) 104 (39-238) mg/24 h. Patients with levels of u-KIM1 in the highest quartile had a greater decline in eGFR than patients with the lowest quartile 6.0 (5.4) versus 3.2 (5.5) ml/min/1.73 m(2) per year (p=0.02). u-NGAL in the highest versus lowest quartile eGFR decline: 5.1 (4.7) and 2.8 (7.1)ml/min/1.73 m(2) per year (p=0.07). Higher values of u-NGAL and u-KIM1 were associated with enhanced decline in eGFR (R=0.16 and R=0.19, p<0.05), however not after adjustment for progression promoters. p-FGF23 was not predictive of decline in eGFR.

Higher levels of markers of tubular damage are associated with a faster decline in eGFR. However, since this is not independent of known progression promoters, measurement of tubular markers does not give additional prognostic information.