• The distribution of RBC lithium ratios in vitro in a recently hospitalized psychiatric population was found to be multimodal. Psychotic patients who had an antipsychotic response during open trials of lithium carbonate alone were identified with high sensitivity (89%), but low specificity (51%) before drug treatment, by lithium ratios that were in the extreme modes of the distribution (<0.30 or >0.38). Diagnostic efficiency of the test was 61%. The DSM-III diagnosis of schizophreniform disorder demonstrated 90% diagnostic efficiency in predicting response/nonresponse during treatment with lithium carbonate alone. A subgroup of the psychotic disorders was similar to affective disorders with respect to course of illness, biological characteristics, and response to lithium carbonate.
Garver DL, Hitzemann R, Hirschowitz J. Lithium Ratio In VitroDiagnosis and Lithium Carbonate Response in Psychotic Patients. Arch Gen Psychiatry. 1984;41(5):497-505. doi:10.1001/archpsyc.1984.01790160083011