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Hemolytic uremic syndrome in children: platelet aggregation and membrane glycoproteins
B Sassetti1, M I Vizcargüénaga, N L Zanaro
1Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Argentina.
Insights
Platelet alterations in hemolytic uremic syndrome (HUS) involve functional decreases and structural membrane changes, particularly with the GPIIbIIIa complex, persisting throughout the initial disease weeks.
Area of Science:
- Hematology
- Pediatric Nephrology
- Thrombosis Research
Background:
- Hemolytic uremic syndrome (HUS) involves microcirculation thrombosis.
- Proposed mechanisms for HUS-related thrombosis lack complete understanding.
- Platelet structure and function are critical in HUS pathogenesis.
Purpose of the Study:
- Investigate platelet structure and function during the initial 4 weeks of HUS.
- Elucidate the mechanisms behind platelet alterations in HUS.
- Understand the role of membrane glycoproteins in HUS platelet dysfunction.
Main Methods:
- Studied coagulation parameters, platelet counts, and aggregation in 49 children with HUS.
- Assessed membrane glycoproteins (GPs) in 20 HUS patients.
- Sequential platelet aggregation and GP analysis during the first 4 weeks of HUS evolution.
Main Results:
- No evidence of disseminated intravascular coagulation in patients with persistent thrombocytopenia.
- All HUS patients exhibited a functional decrease in platelet aggregation during the acute phase.
- Platelet GPs GPIb, GPIIbIIIa, GPIIb, and GPIIIa were evaluated; GPIIbIIIa remained low and subnormal for 4 weeks.
Conclusions:
- Platelet alterations in HUS likely stem from multiple factors.
- Potential mechanisms include platelet 'exhaustion' and structural membrane damage.
- Diminished or nonfunctional GPIb and GPIIbIIIa complexes contribute to HUS pathophysiology.
Purpose:
Several mechanisms have been proposed to explain the fibrin-platelet thrombosis at the microcirculation level in the different clinical conditions of hemolytic uremic syndrome (HUS). The relationships between platelet structure and function during the first 4 weeks of evolution of the disease were studied to understand the mechanism of platelet alteration.
Patients And Methods:
Coagulation parameters, platelet counts, and aggregation were studied in 49 children, and membrane glycoproteins (GPs) in 20 of the 49 children (mean age, 17 months) with HUS (Group 2) were studied during the first 4 weeks of evolution of the disease.
Results:
No disseminated intravascular coagulation was found in patients with recurrent or persistent thrombocytopenia. Platelet aggregation was sequentially performed during the first weeks of evolution. All patients had a functional decrease in the acute period of HUS. Platelet GPs GPIb, GPIIbIIIa, GPIIb, and GPIIIa were evaluated. GPIIbIIIa complex presented low level and never reached normal values during the first 4 weeks of disease.
Conclusions:
Platelet alterations are probably caused by multiple mechanisms: "exhausted" platelets, structural membrane alterations caused by arginine-glycine-aspartic peptide blockade, or diminished or nonfunctional membrane GPIb and GPIIbIIIa complexes.