MLPAO Hematology and Coagulation Advanced Practice Flashcards

What is the clinical significance of fibrin degradation products (FDPs) versus D-dimer?

Answer: FDPs detect degradation of both fibrinogen and fibrin; D-dimer is specific for cross-linked fibrin degradation

FDPs detect degradation products from both fibrinogen and fibrin, while D-dimer specifically detects fragments from cross-linked (Factor XIIIa-stabilized) fibrin. This means D-dimer is more specific for indicating that both clot formation and fibrinolysis have occurred, making it more useful for thromboembolism exclusion.

Which hereditary condition causes increased osmotic fragility of red blood cells?

Answer: Hereditary spherocytosis

Hereditary spherocytosis causes increased osmotic fragility because the spherical red blood cells have decreased surface-area-to-volume ratio and cannot swell as much before lysing in hypotonic solutions. The osmotic fragility test and eosin-5-maleimide (EMA) binding test are used to confirm the diagnosis.

What does an immature platelet fraction (IPF) help assess?

Answer: The rate of platelet production by the bone marrow

The immature platelet fraction measures the percentage of newly released (reticulated) platelets, analogous to the reticulocyte count for red blood cells. An elevated IPF with thrombocytopenia indicates increased platelet destruction (ITP, DIC), while a low IPF suggests decreased bone marrow production.

Which cytochemical stain is positive in acute myeloid leukemia but negative in acute lymphoblastic leukemia?

Answer: Myeloperoxidase (MPO)

Myeloperoxidase (MPO) is present in the primary granules of myeloid cells and is positive in most AML subtypes but negative in ALL. It is one of the key cytochemical markers used to distinguish myeloid from lymphoid lineage in acute leukemia, along with Sudan black B and specific esterase.

What is the difference between type 1, type 2, and type 3 von Willebrand disease?

Answer: Type 1 is quantitative decrease; type 2 is qualitative defect; type 3 is complete absence

Type 1 vWD (most common, ~70-80%) involves a partial quantitative decrease in vWF. Type 2 involves qualitative vWF defects (subtypes 2A, 2B, 2M, 2N have different functional abnormalities). Type 3 (rarest, most severe) involves complete or near-complete absence of vWF. Treatment varies by type.

Which test is used to assess platelet function?

Answer: Platelet aggregation studies using light transmission aggregometry

Light transmission aggregometry (LTA) is the gold standard for assessing platelet function. Platelet-rich plasma is stimulated with various agonists (ADP, collagen, epinephrine, arachidonic acid, ristocetin) and the change in light transmission is measured as platelets aggregate. Abnormal patterns help diagnose platelet function disorders.