The lithium excretion test: I. Clinical application and interpretation.

The clinical and research applications of the Lithium Excretion Test (L.E.T.) are described. With a 4-hour test it is possible to differentiate manic patients who respond to lithium from those who do not. Significant applications for a small but important group of patients with personality disorders are discussed, as well as the findings in depression and schizophrenia.