Diurnal variation of urinary MHPG in unipolar and bipolar depressives

In eight bipolar depressives, 11 unipolar depressives, and 15 healthy controls urinary excretion of MHPG was measured at 3-h intervals over one 24-h period. Bipolars excreted smaller amounts of MHPG than unipolars and controls, especially at night. MHPG excretion was significantly dependent on time of day in the control group only. In the patients maximum excretion showed a tendency to occur earlier in the day than in controls. Minima were unaffected. There were indications that tricyclic antidepressants advance MHPG phases.