A 9-year-old boy is brought to the emergency department by his parents due to prolonged bleeding following a tooth extraction earlier in the day. Past medical history is noncontributory. Temperature is 37.5°C (99.5°F), pulse is 88/min, respirations are 14/min, and blood pressure is 112/62 mmHg. Physical exam shows gingival bleeding and petechiae. Laboratory testing is obtained, and the results are shown below. Laboratory value Result Hematologic Hemoglobin 12 g/dL Hematocrit 40% Platelet count 95,000/mm 3 Leukocyte count 9,000/mm 3 Coagulation studies Prothrombin time (PT) 12 seconds Activated partial thromboplastin time (aPTT) 29 seconds Bleeding time* 15 minutes *Reference Range: 2-7 minutes Which of the following conditions is the patient at greatest risk of developing?

Bleeding from the sphenopalatine artery

Glanzmann's thrombasthenia

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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 9-year-old boy is brought to the emergency department by his parents due to prolonged bleeding following a tooth extraction earlier in the day. Past medical history is noncontributory. Temperature is 37.5°C (99.5°F), pulse is 88/min, respirations are 14/min, and blood pressure is 112/62 mmHg. Physical exam shows gingival bleeding and petechiae. Laboratory testing is obtained, and the results are shown below.

Laboratory value	Result
Hematologic
Hemoglobin	12 g/dL
Hematocrit	40%
Platelet count	95,000/mm3
Leukocyte count	9,000/mm3
Coagulation studies
Prothrombin time (PT)	12 seconds
Activated partial thromboplastin time (aPTT)	29 seconds
Bleeding time*	15 minutes