Glanzmann's thrombasthenia

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Summary of Glanzmann's thrombasthenia

Glanzmann's thrombasthenia is an abnormality of the platelets. It is an extremely rare coagulopathy in which the platelets contain defective or low levels of glycoprotein IIb/IIIa, which is a receptor for fibrinogen. As a result, no fibrinogen bridging of platelets to other platelets can occur, and the bleeding time is significantly prolonged.

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Glanzmann's thrombasthenia

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Chapter 56 Platelet Disorders SIGNS & SYMPTOMS ▪ Mucocutaneous bleeding ▫ Epistaxis; gingival bleeding; petechiae, purpura (coalesced petechiae); GI bleeding; genitourinary bleeding (e.g. hematuria); menorrhagia ▪ Excessive bruising/bleeding after minor trauma; bruises linger ▪ Immediate, excessive bleeding with invasive procedures ▪ Asymptomatic until adulthood DIAGNOSIS LAB RESULTS ▪ CBC ▫ Low platelet count ▪ Peripheral blood smear analysis ▫ Giant platelets (accelerated platelet turnover) ▪ Clotting studies ▫ Bleeding time prolonged (PT, aPTT normal) ▪ Flow cytometry ▫ Deﬁcient/absent GPIb-IX-V complex OTHER DIAGNOSTICS ▪ Physical examination ▫ Purpura ▫ Ecchymoses TREATMENT MEDICATIONS ▪ Avoid antiplatelet medications ▪ Anti-ﬁbrinolytic therapy (e.g. tranexamic acid) OTHER INTERVENTIONS ▪ Platelet transfusions (e.g. prophylaxis before invasive procedures) ▫ HLA matching/leukocyte reduced platelets reduces risk of allo-antibody formation GLANZMANN'S THROMBASTHENIA (GT) osms.it/glanzmanns-thrombasthenia PATHOLOGY & CAUSES ▪ Inherited bleeding disorder, defect in platelet surface receptor αIIbβ3 ▪ Platelet-mediated hemostasis ▫ Binding of platelets to exposed components of injured endothelium through glycoprotein (GP) receptors on platelet surface (e.g. GPIb/IX, GPIa/IIa, integrin αIIbβ3) ▪ Integrin αIIbβ3 defect → impaired platelet clot retraction, altered hemostasis CAUSES ▪ Autosomal recessive inheritance pattern ▪ Rarely, allo-/auto-antibodies to platelet αIIbβ3 produced by autoimmune conditions (e.g. systemic lupus erythematosus, immune thrombocytopenia, myelodysplastic syndrome) during pregnancy/with use of platelet integrin αIIbβ3 antagonists (abciximab, eptiﬁbatide) RISK FACTORS ▪ Slightly more common in individuals who are biologically female ▪ Children of parents who are close relatives OSMOSIS.ORG 445

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Glanzmann's thrombasthenia

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A 4-year-old girl is brought to the pediatrician's office by her grandmother because of multiple ecchymotic patches over both shoulders. Her medical history is relevant for multiple hospital admissions when she was born. Physical exam shows swollen gums, poor dental hygiene, and a petechial rash over her face. Her temperature is 36.4°C ( 97.52°F), pulse is 101/min, respirations are 17/min, blood pressure is 120/70 mmHg. Laboratory studies show prolonged bleeding time, but platelet count and coagulation tests are normal. Which of the following is the most likely cause of this patient's condition?

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