Annals of the Rheumatic DiseuWes 1989; 48: 586-589 Platelet serotonin in systemic sclerosis

SUMMARY Platelet serotonin concentrations were measured in 43 patients with systemic sclerosis, in 11 patients with primary Raynaud's phenomenon, and in 38 normal controls. Patients with the CREST variant (calcinosis, Raynaud's phenomenon, oesophageal dysmotility, sclerodactyly, telangiectasia) had significantly lower platelet serotonin concentrations than normal controls. Patients with diffuse systemic sclerosis had normal platelet serotonin concentra-tions. In patients with CREST treatment with ketanserin, a specific serotonin antagonist, normal-ised platelet serotonin concentrations. These data provide further evidence suggesting that in systemic sclerosis, particularly the CREST variant, there is widespread platelet activation. Microvascular disease is a major feature of systemic sclerosis, with Raynaud's phenomenon occurring in most of the patients. The episodic nature of the ischaemia is suggestive of active vasoconstriction, though structural vessel wall changes have been clearly shown.' Several observations have implicated serotonin a