Abnormal circulating unsaturated fatty acid concentration Abnormal circulating eicosanoid concentration The icosanoids include the prostaglandins, prostacyclins, thromboxanes, leukotrienes, and epoxyeicosatrienoic acids. Icosanoids have various roles in processes that regulate inflammation, fever, blood pressure, blood clotting, immune system function, reproductive processes and tissue growth, and the sleep/wake cycle.