Circulating prostacyclin and thromboxane levels in patients with diabetic retinopathy.

Prostacyclin (PGI2) is the most potent endogenous inhibitor of platelet aggregation yet discovered. Thromboxane (TXA2) promotes aggregation and degranulation of platelets. It is hypothesized that an homeostasis exists between these pathways that is protective against vascular damage and is disturbed in several diseases such as diabetes. Circulating levels of PGI2-TXA2 in 35 patients with adult onset diabetes and 15 controls have been assayed. Twenty patients had background retinopathy, and 15 had proliferative retinopathy. Circulating levels of PGI were found to be elevated in 9/15 patients with proliferative diabetic retinopathy, 2/20 diabetic patients with background or no retinopathy, and 0/15 controls. PGI levels may correlate, therefore, with the severity of the retinopathy.