Section 9: Disorders of Secondary Hemo Factor Def Flashcards
Hemophilia A is what factor deficiency?
FVIII:C
describe Hemophilia A
how common
inheritance
- most common factor deficiency in USA
- X-linked recessive expressed almost exclusively in males
- female carriers generally asymptomatic and produce ~50% of normal VIII
hemophilia A mechanism
- injury to blood vessel -> bleeding
- vessel constricts and clotting factors activate
- lack of VIII causes weak platelet plug to form
- incomplete and/or delayed fibrin clot allows bleeding to continue
hemophilia A VIII activity ref range
50-150%
hemophilia A mild, moderate, and severe VIII activity
mild 5-30% activity
moderate 1-5% activity
severe < 1% activity
hemophilia A lab findings
- bleeding time or PFA normal bc VIII not involved in plt function
- PT normal
- APTT prolonged bc VIII intrinsic
- confirm with factor VIII assay
acquired VIII deficiency causes
- DIC bc VIII gets used up
- liver disease bc not making VIII
hemophilia B factor deficiency
IX
hemophilia B
history and stats
- royal disease
- 2nd most common factor deficiency in the USA
- X-linked recessive almost expressed exclusively in males. Female carriers may have some bleeding problems
hemophilia B clinical bleeding
- varying degrees of severity
- less severe than hemophilia A
hemophilia B lab findings
- PFA normal
- PT normal
- APTT prolonged
- confirm with factor IX assay
acquired factor IX deficiency causes
- DIC
- liver disease
- vit K deficiency (IX one of magic 4)
- oral anticoags (arrest vit K)
fibrinogen disorder list
- afibrinogenemia
- hypofibrinogoenemia
- dysfibrinogenemia
afibrinogenemia
- absence or very low fibrinogen
- hereditary deficiency
- bleeding
hypofibrinogenemia
- fibrinogen < 100 mg/dl
- bleeding but depends how low it gets
dysfibrinogenemia
- functionally abnormal
- bleeding if defective clot formation
- thrombosis if defective fibrinolysis
acquired fibrinogen deficiency causes
- DIC
- fibrinogenolysis
- liver disease
hyperfibrinogenemia
- physiologic stresses cause fibrinogen to increase bc it’s an APP (trauma, pregnancy, tissue inflammation)
- can lead to thrombosis
prothrombin deficiency (Factor II)
- rarest of congenital factor deficiencies
- heterozygotes generally asymptomatic but homozygotes bleed
acquired prothrombin deficiency causes
- DIC
- liver disease
- vit K deficiency
- oral anticoags
Factor V deficiency
- 1/million population
- autosomal recessive
- only homozygotes bleed
- DIC and liver disease -> acquired
Factor VII deficiency
- autosomal recessive
- only homozygotes bleed
- DIC/liver disease/vit K def/oral anticoag -> acquired
factor X deficiency
- autosomal recessive
- heterozygotes mild bleeding
- homozygotes more severe bleeding
- DIC/ liver disease/vit K def/ oral anticoag/amyloidosis
explain amyloidosis in context of factor X deficiency
amyloid plaques can adsorb/sequester factor X from being used
factor XII deficiency
- relatively common
- autosomal recessive
- DIC/liver disease -> acquired
factor XII deficiency lab tests
- APTT will be increased but no bleeding problems bc intrinsic pathway affected. Thrombin can go back to activate XI
- tend to thrombose bc XII involved in plasmin formation
prekallekrein deficiency
- rare: mostly in black fams
- autosomal recessive and dominant
- APTT increased but no bleeding problems
- may lead to thrombosis -> anti-thrombotic therapy
High Molecular Weight Kininogen (HMWK) deficiency
- autosomal recessive
- APTT increased, most asymptomatic
- may lead to thrombosis and need anti-thrombotic therapy
factor XIII deficiency
- very rare
- normal PT and APTT results
- test with urea solubility (clot lysis)
factor XIII deficiency symptoms
- umbilical stump bleeding
- poor wound healing
- bruises resolve slowly
- excessive scar formation
- cranial hemorrhage
what is assumed in disseminated intravascular coagulation (DIC)?
resultant secondary fibrinolysis
DIC mechanism
- trigger leads to increased clotting, which consumes platelets and clotting factors
- overactivates fibrinolysis -> too much bleeding and thrombosis
primary fibrinolysis lab diagnosis
- PT, APTT, TT, CTT all prolonged
- FDP positive
- fibrinogen low
- D-dimer neg
- plt count normal
- peripheral smear normal
Why is CTT prolonged in primary fibrinolysis?
bc FDPs inhibit thrombin
secondary fibrinolysis lab diagnosis
- PT, APTT, TT, CTT all prolonged
- FDP positive
- fibrinogen low
- D-dimer positive
- plt count low
- peripheral smear schistocytes
which lab tests help distinguish btwn primary and secondary fibrinolysis?
D-dimer
plt count
peripheral smear
FDP assay
chronic DIC (aka compensated)
- cirrhosis and metastatic cancer
- less critical bleeding and more diffuse thrombosis
- proceeds more slowly -> body compensates for loss of factors and plts better
liver disease
- liver makes all coag factors, plasminogen, antithrombin, and alpha-2-antiplasmin
- results in deficiency/dysfunction/impaired clearance of factors/inhibitors
- accumulate plasminogen activators -> DIC
- bleeding or thrombosis
renal disease
- thrombosis and bleeding
- nephrotic syndromes (lose some factors, AT, Protein C in urine; uremia pt have decreased plt/impaired plt function)
- in DIC fibrin deposition results in renal damage
vit K deficiency
- factors II, VII, IX, and X vit K dependent
- Protein C also vit K dependent
massive transfusions
- storage of labile factors lose V and VIII which affect screening tests but seldom cause bleeding problems
- citrate toxicity rarely a problem except in newborns or big transfusions
- thrombocytopenia -> plt lose viability in stored blood
