Lithium and electrolytes plasma/RBC ratio and paradoxical lithium neurotoxicity.

1. Although lithium neurotoxicity and EEG disturbances are known to be associated with toxic plasma lithium levels, it may also be paradoxically manifested when plasma lithium levels are within the therapeutic range. 2. Plasma and RBC lithium and electrolytes levels were measured in 50 patients with affective disorders during the course of lithium therapy. Seventeen of them suffered from lithium neurotoxicity. 3. It is suggested that in the course of lithium treatment, in the manic and depressed phases as well as during prophylaxis, lithium ratio is a better correlate of lithium neurotoxicity than plasma lithium alone, even when the plasma lithium levels are within the therapeutic range. 4. In addition, an increase in the intra-erythrocyte sodium/potassium ratio was observed in toxic patients in comparison to non-toxic patients.