Fractional excretion of TNF receptor 1 and 2 in patients with type 2 diabetes and normal renal function.

AIMS/INTRODUCTION Increased concentrations of serum tumor necrosis factor (TNF) receptors (TNFRs; TNFR1 and TNFR2) are positively associated with the urinary albumin-to-creatinine ratio (ACR) and negatively associated with the estimated glomerular filtration rate (eGFR) in patients with type 2 diabetes. However, the mechanism underlying this increase and the relationship between TNFRs in serum and urine and kidney measures (ACR and eGFR) are unclear. MATERIALS AND METHODS This was a cross-sectional study that included 499 patients with type 2 diabetes and eGFR ≥60 mL/min/1.73 m2 . The concentrations of TNFRs in serum and urine and their respective fractional excretion (FE) were measured. RESULTS Serum and urinary TNFR levels were positively associated with the ACR and negatively associated with the eGFR. The FE of TNFRs did not differ between patients with an eGFR ≥90 and those with an eGFR 60 to 89 mL/min/1.73 m2 and also did not correlate with eGFR. After adjustment for relevant covariates, the serum TNFRs were associated with a lower eGFR (60-89 mL/min/1.73 m2 ) and an increased ACR (≥30 mg/gCr), but urinary TNFRs were associated with an increased ACR (≥30 mg/gCr) alone, in the multivariate logistic model. CONCLUSIONS The pattern of FE TNFRs demonstrated that an increase in serum TNFRs may result from their increased systemic production, including in the kidney, rather than being a simple reflection of GFR decline. Kidney measures appear to be strongly associated with serum TNFRs rather than urinary TNFRs in patients with type 2 diabetes and normal renal function.