PLATELETS, SEROTONIN, MIGRAINE, AND IMMUNE-COMPLEX DISEASE
StR,—Damasio’ and Damasio and Beckhave shown that migraine may be associated with some forms of thrombocytopenia. Of 296 patients with various forms of thrombocytopenia whom they studied, 14 had migraine or migraine-like headaches; and of these 14, 11 had idiopathic thrombocytopenia (I.T.P.) and 3 systemic lupus erythematosus (S.L.E.). None of the 282 with other causes for thrombocytopenia had migraine,4and the association of migraine with S.L.E. has been recorded.3 Damasio and Beck relate the migraine to attacks of
a fall in total available blood-serotonin, associated with the fall in platelet count. During migraine attacks a fall in intraplatelet serotonin with a normal platelet count has been reported.5 We have measured the intraplatelet and free plasma serotonin in 33 patients with S.L.E., and in 3 patients with I.T.P. in relapse. All 3 patients with I.T.P. and 2 of the patients with S.L.E. had depressed platelet counts (< 150 x 109/1). In normal individuals the plasma-serotonin was 26-38 ng/ml (geometric mean±s.E.M.) and was raised to 71-113 ng/ml in patients with S.L.E. In the three patients with active I.T.P. it was 212, 72, and 268 ng/ml. The normal platelet serotonin of 224±26 (s.E.M.) ng/109 platelets was reduced in the patients with S.L.E. to 38±12 ng/109. In 5 of these patients with S.L.E., and in all 3 patients with active I.T.P., there was no detectable intraplatelet serotonin (