Tyramine conjugation test distinguishes unipolar from bipolar depressed patients and controls.

Tyramine sulphate conjugation following oral tyramine administration (the tyramine test) has previously been found to distinguish endogenous unipolar from neurotic depression and appears to be a trait marker. In this study, the test was used in 24 unipolar depressed patients compared with similar sized matched groups of bipolar depressed patients and normal controls. Most of the depressed patients in each group showed endogenous features. The study found that whereas tyramine sulphate conjugation was significantly impaired in unipolar patients, values in the bipolars were similar to those of controls. These results provide further evidence for the biological difference between unipolar and bipolar depression.