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Platelet hyperaggregation and increased plasma level of Von Willebrand factor in diabetics with retinopathy
Insights
Platelet hyperaggregation in diabetics with severe retinopathy is linked to platelet membrane factors, not plasma. Proliferative retinopathy shows high von Willebrand factor (VIII VWF) but normal antihemophilic factor (VII AHF).
Area of Science:
- Endocrinology and Metabolism
- Hematology and Coagulation Disorders
- Ophthalmology and Vascular Complications
Background:
- Diabetic retinopathy is a microvascular complication of diabetes mellitus.
- Altered hemostasis and platelet function are observed in diabetes.
- The role of platelet and plasma factors in diabetic retinopathy pathogenesis is not fully understood.
Purpose of the Study:
- To investigate in vitro hemostasis in insulin-dependent diabetics with varying stages of retinopathy.
- To determine the contribution of platelet versus plasma factors to ADP-induced platelet hyperaggregation.
- To assess levels of von Willebrand factor (VIII VWF) and antihemophilic factor (VII AHF) in relation to retinopathy severity.
Main Methods:
- Studied 18 insulin-dependent diabetics (6 without retinopathy, 6 with proliferative retinopathy, 6 treated with hypophysectomy).
- Assessed platelet aggregation using adenosine diphosphate (ADP) and thrombin.
- Measured von Willebrand factor (VIII VWF) via ristocetin-induced platelet aggregation and antihemophilic factor procoagulant activity (VII AHF).
Main Results:
- ADP-induced platelet hyperaggregation in diabetics with severe retinopathy was attributed to a platelet factor, likely involving the platelet plasma membrane.
- Thrombin-induced aggregation results were normal, supporting a specific defect in ADP-mediated pathways.
- Elevated plasma levels of von Willebrand factor (VIII VWF) were found in patients with proliferative retinopathy; VII AHF levels remained normal.
Conclusions:
- Platelet membrane abnormalities contribute to hypercoagulability in diabetic retinopathy.
- Elevated VIII VWF levels correlate with proliferative diabetic retinopathy.
- These findings suggest specific hemostatic alterations in diabetic retinopathy that may influence disease progression.
Abstract:
In 18 insulin-dependent diabetics (6 without retinopathy, 6 with proliferative retinopathy and 6 with proliferative retinopathy treated by hypophysectomy) matched for age and duration of diabetics, in vitro haemostasis was studied using ADP induced platelet aggregation, ristocetin induced platelet aggregation which allows von Willebrand factor (VIII VWF) assay, and determination of antihemophilic factor procoagulant activity (VII AHF). Using gel filtration-isolated platelets, the ADP induced hyperaggregation previously reported in diabetics with severe retinopathy untreated by hypophysectomy appeared to be related to a platelet and not a plasma factor; the normal results of thrombin induced aggregation suggests that the presumed abnormal platelet factor is related to the platelet plasma membrane. High level of plasma VII VWF was observed in diabetics with proliferative retinopathy while the VII AHF level was within normal limits.