vitamin K deficiency
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Etiology
- absent intake of vitamin K with or without antibiotics
- malabsorption syndromes
- warfarin
- ingestion of new 'super warfarins' used in rat poisons
- genetic defects in vitamin K-dependent clotting factors
Pathology
- defect in post-translational modifications of coagulation factors, factor II, factor VII, factor IX & factor X by vitamin-K dependent carboxylase
- functional activity of coagulation factors disappear from plasma in order: factor VII < factor IX < factor X < factor II (increasing 1/2 lives)
- vitamin K stores are limited
Genetics
- associated with defects in VKORC1 gene
Laboratory
- prolonged prothrombin time (PT)
- frequently aPTT is also prolonged
- plasma coagulation factor II activity, factor VII activity, factor IX activity & factor X activity (diminished activities)
- factor V activity is diminished in liver failure, but not vitamin K deficiency (compare with factor VII)
Management
- ingestion of new 'super warfarins' (rat poison)
- 'super warfarins' have very long 1/2 lives (months)
- unresponsive to usual doses of vitamin K
- vitamin K
- 0.5-1.0 mg IV generally corrects coagulation defect
- vitamin K 10 mg SC QD for 3 days is common practice
More general terms
Additional terms
- coagulation factor IX; Christmas factor; plasma thromboplastin component; PTC; contains: coagulation factor IXa light chain; coagulation factor IXa heavy chain (F9)
- coagulation factor VII; proconvertin; serum prothrombin conversion accelerator; SPCA; Eptacog alfa; contains: factor VII light chain; factor VII heavy chain (F7)
- coagulation factor X; Stuart factor; Stuart-Prower factor; contains: factor X light chain; factor X heavy chain; activated factor Xa heavy chain (F10)
- prothrombin; coagulation factor II; contains: activation peptide fragment 1; activation peptide fragment 2; thrombin light chain; thrombin heavy chain (F2)
- vitamin K
References
- ↑ Medical Knowledge Self Assessment Program (MKSAP) 11, 18. American College of Physicians, Philadelphia 1998, 2018.
- ↑ Brenner B, Kuperman AA, Watzka M, Oldenburg J. Vitamin K-dependent coagulation factors deficiency. Semin Thromb Hemost. 2009 Jun;35(4):439-46. Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/19598072