RBC-choline: changes by lithium and relation to prophylactic response.

Red blood cell (RBC)- and plasma-choline levels were measured in patients on lithium (n = 96), antidepressants (n = 32) and neuroleptics (n = 51), and in 25 healthy drug-free controls. Lithium patients exhibited highly increased RBC- and slightly increased plasma-choline levels compared with controls (P less than 0.001 and P less than 0.05, respectively); the choline ratio (RBC-/plasma-choline) was elevated almost to the same extent as RBC-choline (P less than 0.001). With antidepressants RBC-choline and choline ratios were slightly reduced (P less than 0.05), whereas neuroleptics showed no effect on choline levels. 79% of lithium patients were responders (reduction in hospitalizations with lithium), 21% were non-responders (no reduction or increase in hospitalizations). Choline ratio exhibited a significant relation to prophylactic lithium response, but lithium ratio did not. The percentage of non-responders was significantly higher in patients with a choline ratio exceeding 100 than in patients with a choline ratio below this cut-off (P less than 0.01). Thus, the increase of RBC-choline and choline ratios appears to be an effect specific for lithium and might be related to the outcome of lithium prophylaxis.