CSF enkephalins in diabetic neuropathy

CSF methionine and leucine enkephalins were measured by high performance liquid chromatography and radioimmunoassay in diabetic patients with painful neuropathy (n = 22) and painless neuropathy (n = 5), and non-diabetic subjects with low back pain (n = 11). Wide variations in CSF enkephalin levels were found and they were often below the limit of detection (less than 0.1 pmol/l) in the diabetic and non-diabetic groups. The origin of CSF enkephalins is unknown and CSF levels may not reflect tissue concentrations. In conclusion, CSF enkephalin levels are difficult to interpret and do not provide useful information on the function of enkephalinergic pathways.