Sodium-dependent lithium efflux from red cells in affective disorders

Steady state red blood cell/plasma lithium concentration ratios were determined simultaneously with the in vitro sodium-dependent downhill lithium efflux from red cells during maintenance lithium treatment in 22 bipolar depressed patients, 17 unipolar depressed patients, and 28 psychiatric control patients. The values of the sodium-dependent lithium efflux were significantly correlated with the steady-state lithium levels in red blood cells and plasma. A profound difference in sodium-dependent lithium efflux from red cells was found between controls and bipolar patients and to a lesser degree between controls and unipolar patients.