Effect of erythropoietin therapy on polyneuropathy in predialytic patients

Peripheral neuropathy commonly develops in patients with advanced chronic renal failure. The uremic neuropathy is often subclinical and detectable only by electrophysiological studies. Receptors to erythropoietin (EPO) have been described on non-hematopoietic cells including neuronal cells.

In order to evaluate the effect of five months' EPO therapy on polyneuropathy in predialytic patients, nerve conduction studies (NCS) were done in 46 anemic predialytic patients without neurological complaints. In 22 (twelve non-diabetic and ten diabetic) neuropathy was detected and these patients were included in the study. After five months of subcutaneous EPO therapy NCSs were repeated.

Hemoglobin increased significantly (p=0.0001) with no significant increase in plasma creatinine. Motor nerve conduction velocity (MNCV) and compound muscle action potentials (CMAP) of the ulnar nerve were normal before EPO therapy and at the end of the study. MNCV of the median, peroneal and tibial nerves improved significantly (p<0.05). CMAP of the median nerve rose significantly, to the normal range (p=0.01). Sensory nerve conduction velocity (SNCV ) and sensory nerve action potentials (SNAP) were reduced in all sensory nerves and did not improve. The improvement in non-diabetic patients was better than in diabetic patients. No significant correlation was found between the increase in hemoglobin and the improvement in MNCV.

Subcutaneous EPO therapy improved motor polyneuropathy in uremic patients, especially non-diabetic individuals. The improvement in MNCV may reflect remyelination. This non-hematopoietic effect may be related to some direct action through EPO receptors on peripheral neuronal cells.