Erythrocyte lithium transport variables as a marker for manic-depressive disorder.

This study examines whether variability in the efflux of lithium from erythrocytes may be a marker for manic-depressive disorder in related individuals. The subjects of the study were 73 individuals from 12 families in which there was more than one bipolar manic-depressive member. Using an in vitro procedure, we subjected erythrocytes to four conditions which are believed to inhibit lithium efflux. Only phloretin, an inhibitor of Na+-Li+ countertransport, produced significant inhibition. Variability in this inhibition was not related to the presence or absence of manic-depressive disorder, although it was related to family membership. The implications of these findings are discussed.