Tumor necrosis factor alpha as a uremic toxin: correlation with neuropathy, left ventricular hypertrophy, anemia, and...

Tumor necrosis factor alpha (TNF alpha) is usually excreted by the kidney. In dialysis patients, it accumulates. TNF alpha has been implicated in the pathogenesis of malnutrition, diabetic neuropathy, and erythropoietin resistance. We studied TNF alpha plasma levels in 49 stable peritoneal dialysis (PD) patients, with the aim of correlating those levels with the presence and severity of peripheral neuropathy, hypertrophic cardiomyopathy, and anemia. Kt/Vurea' residual renal creatinine clearance (CrC), nutritional markers, and general biochemistry were also determined. The average plasma level of TNF alpha was 67 +/- 32 pg/mL (range: 18.1-156.3 pg/mL; normal value 3-20 pg/mL). No correlation was observed between TNF alpha and KT/Vurea' but a negative correlation with CrC was seen (r: -0.37, p < 0.05). TNF alpha levels were higher in patients with neuropathy as compared to patients with normal results (72.5 +/- 32 pg/mL vs 44 +/- 22 pg/mL, p < 0.05). Patients with neuropathy also showed a lower CrC value (1.5 +/- 1.7 mL/min vs 3.9 +/- 2.6 mL/min, p < 0.01). TNF alpha levels were higher in patients with left ventricular hypertrophy (LVH) with respect to normal individuals (70.4 +/- 32 pg/mL vs 38.5 +/- 20.8 pg/mL, p < 0.05). Patients with severe LVH showed the lowest CrC value. A direct, significant relationship was found between TNF alpha levels and weekly erythropoietin dose (r: 0.41, p < 0.05). Patients with hypertriglyceridemia or taking lipid-lowering agents showed a positive linear correlation between TNF alpha and triglycerides (r = 0.7, n = 14, p < 0.05). These data suggest that accumulation of TNF alpha may contribute to the development or maintenance of some neurologic, hematologic, and cardiac complications of uremic syndrome. Loss of residual renal function conditions an increment in TNF alpha levels. These data continue to add support to the idea that TNF alpha may be considered a uremic toxin.