Urinary heme oxygenase-1 as a new and early marker of diabetic nephropathy

Abstract

Introduction Microalbuminuria is considered an early marker of glomerular injury in patients with diabetes, but tubular injury can precede glomerular injury and cannot be detected by microalbumin. We need a new and early marker of kidney injury in normoalbuminuric diabetic patients. Urinary heme oxygenase-1 (uHO-1) is an enzyme that is produced in tubules in response to oxidative stress and can be a marker of tubular injury. Aim To investigate the clinical implication of uHO-1 as an early diagnostic marker in diabetic nephropathy (DN). Patients and methods A total of 65 diabetic patients, comprising 20 microalbuminuric patients and 45 normoalbuminuric patients, and 20 healthy participants as a control group were included in this study. Level of uHO-1 was detected by enzyme-linked immunosorbent assay. Results uHO-1 was highly significantly elevated (P<0.000) in microalbuminuric group compared with normoalbuminuric group and control group, respectively. Normoalbuminuric group was highly significantly elevated (P<0.000) in uHO-1 compared with the control group. uHO-1 was positively correlated with albumin–creatinine ratio but was not correlated with estimated glomerular filtration rate. Receiver operating characteristic curve analysis of uHO-1 levels for early diagnosis of DN revealed that the cutoff value of uHO-1 was 5.8 ng/ml (sensitivity 80% and specificity 71%) for early diagnosis of DN. Conclusion The findings of this study indicate that elevated levels of uHO-1 can be detected in normoalbuminuric diabetic patients and revealed renal tubular damage. uHO-1 may be used as an early biomarker for DN.

Keywords

• diabetic nephropathy
• heme oxygenase-1
• oxidative stress
• renal tubular injury