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Coagulation

Coagulation laboratory tests

High molecular weight kininogen assay


Reviewers: Julie Gober-Wilcox, M.D., Resident, University of New Mexico; Kendall Crookston, M.D., Ph.D., University of New Mexico (see Reviewers page)
Revised: 26 July 2011, last major update July 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.

Definition
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● High molecular weight kininogen deficiency is a congenital disorder that is inherited as an autosomal recessive trait and is not associated with a bleeding diathesis
● It is typically discovered in individuals with an isolated prolonged PTT

Terminology
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● High molecular weight kininogen is also known as Fitzgerald factor, Williams factor and Flaujeac factor

Epidemiology
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● Rare

Pathophysiology
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● High molecular weight kininogen is a protein produced by the liver (with no inherent catalytic activity) that is involved in the early steps of the intrinsic coagulation pathway; it functions as a cofactor and binds with prekallikrein and factor XI to help facilitate their activation by factor XIIa
● The kininogens (low and high molecular weight) are also involved in the kinin-kallikrein system and function to inhibit thrombin activation of platelets and stimulate liberation of nitric oxide, prostacyclin and tissue plasminogen activator

Etiology
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● Deficiency is inherited in an autosomal recessive pattern

Clinical features
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● Not associated with bleeding

Laboratory
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● Isolated prolonged PTT
● Negative lupus anticoagulant
● Specific assay to test for deficiency uses high molecular weight kininogen deficient plasma mixed with patient plasma; a PTT is performed and is compared to a standard curve of high molecular weight kininogen vs. PTT
● Interference occurs in these assays if patient is on heparin, hirudin or argatroban, possibly danaparoid
● Lower levels in newborns, increase to adult levels by age 6 months

Case reports
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● High molecular weight kininogen deficiency in a cardiac surgery patient (Thromb Haemost 2001;85:195)

Differential diagnosis
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● Lupus anticoagulant
● Factor XII deficiency

Additional references
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Consultative Hemostasis and Thrombosis (2007)

End of Coagulation > Coagulation laboratory tests > High molecular weight kininogen assay


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