Metabolism and menstrual cycle rhythmicity of serotonin in primary headaches.

We investigated the platelet and plasma levels of serotonin and its metabolite, 5-hydroxyindoleacetic acid, in patients suffering from episodic tension-type headache and migraine with and without aura, during headache-free period. In female subjects, blood samples were drawn during the follicular, ovulatory, and late luteal phases of the menstrual cycle. In tension headache and migraine with aura, the group mean values of serotonin and 5-hydroxyindoleacetic acid in platelets and plasma were significantly increased, but migraine without aura patients' levels were normal. The pattern of menstrual cycle-related fluctuations in platelet serotonin levels were similar in female patients with tension headache and in controls, with a maximum value in the follicular phase. In both migraine groups, in contrast, the peak occurred in the ovulatory phase. The results are discussed in view of whether these aberrations in peripheral markers of the metabolism and menstrual cycle-related rhythmicity of serotonin may reflect similar alterations in the central nervous system.