Platelet Aggregation in Patients Susceptible to Malignant Hyperthermia

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Abstract
The laboratory diagnosis of malignant hyperthermia (MH) is made by assessing the response of biopsied skeletal muscle to halothane and caffeine. Platelet aggregation might be abnormal in MH patients and might be a less invasive test for MH susceptibility than muscle biopsy. The soluble aggregating agents ADP and epinephrine were used to assess platelet aggregation and 14C-serotonin release in 5 unrelated patients (4 males, 1 female) who had clinical evidence of MH. MH was confirmed by testing of biopsied skeletal muscle for response to halothane and/or caffeine. Aggregation was quantified by measuring light transmission following incubation of platelet-rich plasma with aggregating agents for 10 min. Serotonin release was quantitated simultaneously in each aliquot. Irreversible aggregation was observed in platelets challenged by ADP and epinephrine and confirmed by serotonin release in all 5 patients. Except for 1 patient, an 18-yr-old man, whose platelets were hypersensitive to epinephrine, aggregation and serotonin release thresholds corresponded closely with those previously reported in 23 normal random donors. Routine measurement of platelet reactivity cannot be used as a screening method for MH susceptibility.