Myoinositol--a uremic neurotoxin?

In 28 patients predialysis plasma myoinositol was significantly elevated to 10.8 +/- 2.5 versus 0.75 +/- 0.15 mg/100 ml in normals (mean +/- 1 SD), and was weakly correlated with plasma creatinine concentrations (r = 0.42, p less than 0.05). Dialysis decreased plasma myoinositol concentrations to 3.5 +/- 1.1 mg/100 ml. In 16 patients studied more extensively plasma myoinositol was similarly elevated to 10.6 +/- 3.4 mg/100 ml, and spinal fluid myoinositol was increased to 9.4 +/- 2.3 mg/100 ml (versus 2.7 +/- 0.7 in normals, p less than 0.001). Nerve conduction velocities were reduced in 15 and EEG tracings were abnormal in 12 of the 16 patients. However, neither spinal fluid nor plasma myoinositol showed any correlation with nerve conduction velocities or EEG changes (r = 0.05-0.20, NS) Myoinositol is one of the substances retained in renal insufficiency but no indication was found that it is a toxin causing uremic neurological disturbances.