Serum indoxyl sulfate levels in patients with diabetic nephropathy: Relation to renal function

Aims: To investigate the relationship between serum level of indoxyl sulfate, a tissue damaging factor, and renal function in type 2 diabetic patients. Methods: One hundred and sixty-three patients with type 2 diabetes and serum creatinine of 1.5 mg/dL or below were studied. Serum indoxyl sulfate levels were measured, and general laboratory parameters and patient background were investigated. The relationship between serum indoxyl sulfate level and renal function was analyzed. Results: A strong negative correlation was observed between serum indoxyl sulfate level and renal function (estimated glomerular filtration rate) (r = -0.4355, p < 0.001). Serum indoxyl sulfate also showed a significant positive correlation with serum creatinine and urea nitrogen, and a negative correlation with hematocrit and hemoglobin. When the patients were stratified by the estimated glomerular filtration rate, serum indoxyl sulfate was elevated in groups with estimated glomerular filtration rates of 60-89 mL/min/1.73 m(2) and below. Conclusion: The present results demonstrate a clear correlation between serum indoxyl sulfate level and renal function, suggesting that the removal of indoxyl sulfate may be needed from the early stage of diabetic nephropathy. (C) 2008 Elsevier Ireland Ltd. All rights reserved.