Circulating kidney injury molecule-1 as a biomarker of renal parameters in diabetic kidney disease

Aims/Introduction Urinary kidney injury molecule-1 (KIM-1) has been associated with proximal tubular damage in human and animal studies. Although it has been recognized as a biomarker of acute kidney injury and chronic kidney disease, its significance in the serum remains unclear. Therefore, we examined the relationship of serum and urinary KIM-1 levels with renal parameters in patients with type 2 diabetes. Materials and Methods Serum and urinary KIM-1 levels, together with urinary liver-type fatty acid-binding protein, were measured in 602 patients with type 2 diabetes and an estimated glomerular filtration rate (eGFR) >= 30 mL/min/1.73 m(2). These were then compared with the urinary albumin-to-creatinine ratio and eGFR. Results The serum and urinary KIM-1 levels were significantly different among the three (eGFR >= 60, 45-59, <45 mL/min/1.73 m(2)) groups. These levels were positively associated with the albumin-to-creatinine ratio and negatively associated with eGFR. In a multivariate logistic model, both serum and urinary KIM-1 were associated with an increased albumin-to-creatinine ratio (>30 mg/g Cr), but only the serum KIM-1 was associated with a lower eGFR (<60 mL/min/1.73 m(2)), after adjustment for covariates. Conclusions Renal parameters appear to be strongly associated with serum KIM-1, and not urinary KIM-1, in patients with type 2 diabetes and an eGFR >= 30 mL/min/1.73 m(2).