Haematology Flashcards
What is primary haemostasis?
Through platelet adhesion, aggregation and activation (release granules that promote coagulation and trigger cascade)
What is the intrinsic factor activated by?
Activated by collagen and activated platelets
What factors are involved in intrinsic pathway?
12 12a
11 11a
9 9a
8 8a common pathway
What factor if important to factor 8?
Note, factor 8 activated by thrombin and needs to be bound to vWF factor or will deplete
What pathways do APTT and PT measure?
APTT- intrinsic (plays table tennis- indoors)
PT- extrinsic (plays tennis- outdoors, needs tissues , 7x world champion)
What is the extrinsic pathway activated by?
Tissue factor from damaged endothelial tissue
What factors are involved in extrinsic pathway?
Factor 7
What can prolong PT?
So obviously: deficiency in factors involved which are 7, 10, 5, 2, 1 and 13
Vitamin K related:
Vitamin K antagonists ie Warfarin
Haemorrhagic disease of the newborn (secondary to low Vit K which affects 2, 7 and 10)
Intestinal reabsorption disorders
Vit K deficiency
Liver failure- production issue
Fibrinolysis
DIC (consumptive)
Clotted samples
Very high doses of heparin
** NOTE: Factor 7 lower in healthy newborns vs older kids** Also applies to other Vit K dependant factors
What can prolong APTT?
Deficiency in factors involved: 12, 11, 9, 8, 10, 5, 2, 1, 13
Presence of inhibitors – lupus inhibitors/specific factor inhibitors. Lupus anticoagulant common prolongator post infection
Heparin therapy/accidental contamination (inactivate Xa and thrombin)
LMWH can affect APTT at higher doses
Presence of para protein ie IgA myeloma due to interference with fibrin polymerisation
Clotted sample due to consumption of fibrinogen
Haemophilia
What is Haemophilia A? Name route of inheritance and presentation
Factor VIII deficiency- most severe and most common
8 is in intrinsic pathway so affects APTT
X-linked recessive
Easy bruising (ecchymosis), haematomas, haemarthrosis
What is a side effect of factor replacement?
Can develop inhibitory alloantibodies, usually after 50-100 doses
Diagnosed by inability of pooled plasma to correct prolonged APTT of patient’s plasma
What is Haemophilia B? And mode of inheritance?
Deficiency in factor 9, X- linked reccessive
What is Haemophilia C? Mode of inheritance?
Factor 11 def. Autosomal and commonly seen in Ashkenazi Jews
What is a rare cause of delayed bleeding from umbilical stump?
Factor 13 deficiency, autosomal recessive. Very rare.
What is VWF and VWB disease?
VWF is a carrier for Factor 8 and in vWB disease, there is a deficiency which means factor 8 is consumed faster
What are the types of VWD?
Type 1: QUANTITATIVE def in 70%
Type 2: QUALITATIVE def
Type 3: Total def – like Haemophilia A. Autosomal recessive and can prolong APTT.
Ristocretin sign of qualitative measure
Treatment for VWB disease?
Treatment: DDAVP. Releases vWB from granules but finite resource
THis medication is also used for diabetes insipidis.
Whats the most common cause of prolonged APTT post viral illness?
Lupus anticoagulant
What are causes of congnital thrombocytopenia with SMALL platelets?
Wiskott Aldrich syndrome and X-linked thrombocytopenia. (x-linked essentially has less severe eczema)
Where does haematopoeisis first commence and what is the time period?
Yolk sac, on day 10-12 and then until weeks 10-12. Liver takes over post.
When does hepatic haematopoeisis commence and what is the time frame?
6-8 weeks and continues all through pregnancy but starts to diminish around second trimester as myeloid begins
When does haematopoeisis begin in the BM?
Around 4 months (20-24 weeks) and this is the predominant form in third trimester
When does neutrophil production commence?
10-11 weeks and becomes the primary granolucyte after 14 weeks. Neutrophils are low until the third trimester.
What are granulocytes?
Anything that ends in phil ie basophil, neutrophil, eosinophils
Post-birth, where is EPO produced and when is the peak response?
90% kidney, 10% liver. Responds within minutes to hours, peaking at 24 hours
Where is EPO produced in the foetus?
Usually in liver in first and second trimester, and then kidney takes over
How many globin meoities bind to form a hmaebologin molecule?
4
What is HbA?
a2b2
What is HbF?
a2y2- (alpha and gamma) predominates from 8 weeks gestation and peak at 24 weeks (6 months.) 70% of Hb at birth and slowly drops to 2% by 6 months
Foetal- alphabetical FG- gamma
Where is folate absorbed?
Proximal small intestine, as methyltetrahydrofolate
What common antiepileptics cause malabs of folate?
Phenytoin and phenobarbital
F for folate, F for Fenytoin and Fenobarbitoil
What is the main function of B12?
B12/Colbalmin = Coverts homocystiene to methionine (H&M)
What is the criticial function of folate?
For DNA synthesis
How are B12 and folate related?
B12 is a co-factor for folate absorption so reduces utilisation of folate.
What is the treatment dose for iron?
6mg/kg/day for 3 months
What is the limit for cows milk inake in kids ?6 months
600mls.
What are the factors that increase Hb oxygen affinity?
INCREASED AFFINITY so LEFT SHIFT because for the same CONCENTRATION its REDUCED saturations. Decreased temp, decreased 2-3 DPG, Decreased H+, carbon monoxide and increased fetal Hb
What factors reduce oxygen affinity?
REDUCED affinity so RIGHT shift as MORE saturations for SAME oxygen conc. Increased H+, increased temperate, increased 2-3DPG (technically CO2 as it causes acidosis)
What and where is the protein defect in hereditary spheocytosis?
cytoskeletal protein defects in Ankyrin- protein 3.
What is the mode of transmission for spherocytosis?
Autosomal dominant, most common in northern european
What can trigger an aplastic crisis in spherocytosis?
Parvovirus
What is the treatment for spherocytosis?
Severe: transfusion, folic acid (1mg) and spleenectomy if transfusion dependant, FTT or gallstones
Hereditary elliptocytosis- protein defect?
Spectrin, protein 4.1
What are common triggers for G6PD? (4)
Fava beans, napthalene exposure, anti-malarials, sulfamethoxazole (sulfur containing drugs). Triggered by oxidative stress
What is the inheritance for G6PD?
X-linked recessive
What is seen on the film for G6PD?
Heinz body (REMEMBER FAVA HEINZ BEANS)
What is in the red pulp for spleen?
splenic cords and venous sinus. Essentially removes foriegn materia+erythrocytes and stores iron, RBC and platelets.
What does the white pulp of the spleen contain?
25% of bodies’ lymphocytes and initiates responses to blood bourne antigens. Consists of periarterioral lymphoid sheath (PALS), follicles and marignal zone
What does the white pulp of the spleen contain?
25% of bodies’ lymphocytes and initiates responses to blood bourne antigens. Consists of periarterioral lymphoid sheath (PALS), follicles and marignal zone
What is seen on the blood film for hyposplenism?
howell jolly bodies
What is TEC?
Transient erythroblastopaenia of childhood. Diagnosis of exclusion- essentially subacute pallor and becoming unwell. Normocytic, normochromic anaemia, low retics and erythroblasts in marrow. Usually recovers in 2-8 weeks.
What can trigger TEC?
(transient erythroblastopenia of childhood)
Viral illness, drugs, malignancy, genetic (diamond-blackfan)