Fluctuation of 5-hydroxy-indole compounds in the urine of migrainous patients.

In 14 migrainous patients during different clinical phases the urinary excretion of 5-hydroxy-tryptamine (5-HT) and its main metabolite, 5-hydroxyindoleacetic acid (5-HIAA) were followed. In the course of headache attack a significant increase in 5-HIAA excretion rate was found; at the same time the excretion of 5-HT was not significantly changed. After migraine attack a very pronounced lowering in excretion rate of both 5-hydroxy-indoles occured. The reserpine provocation test was followed by an intensive enhancement of urinary 5-hydroxyindole excretion, but the decrease thereafter was less expressed than after spontaneous attack. These findings lend support to the theory of an abrupt fall in total plasma 5-HT as a trigger mechanism for the painful phase of migraine.