PATH LAB Flashcards
During primary homeostasis, what occurs in these stages:
- adhesion
- activation
- aggregation
- adhesion: platelets adhere to subendothelium via vWF
- activation - platelets activated resulting in shape change, release of ADP and thromboxane A2
- aggregation - more platelets recruited to form haemostatic plug
What does PT and APTT measure? and what does it mean if they are prolonged?
PT - extrinsic and common pathway
– FVII deficiency inherited or due to DIC, warfare, vit K deficiency
APTT - intrinsic and common pathway
– haemophilia (FVIII deficiency), FIX + FXI deficiencies, VWD
Both prolonged = FX deficiency
What factors are in the extrinsic pathway and what triggers it?
Tissue factor activates FVII
What factors are in the intrinsic pathway and what triggers it?
Surface contact - FXII, XI, IX, VIII
What is DIC and what would investigations show?
DIC - systemic activation of blood coagulation resulting in intravascular coagulation and depletion of platelets, coagulation factors and fibrinogen and bleeding complications
Investigations: low platelets, prolonged INR (PT), SPTT, TT and decreased fibrinogen and factors
During group and screen for transfusions, what is the forward group, reverse group and control?
Forward - patient RBC + anti-A/B/RhD antibodies
Reverse - patient serum + group A / B cells to confirm group
Control - patient RBC + no antibody to ensure no spontaneous agglutination
What is a crossmatch?
Patient serum + donor RBC to check for agglutination
Where does haematopoiesis occur in adults?
pelvis, sternum and vertebral bodies
How is acute leukaemia defined and what are the types?
> 20% blast cells in bone marrow at presentation
- AML: failure of myeloid cells to differentiate beyond blasts (Auer rods indicate faggot cells and AML)
- ALL: in bone marrow, lymphoid precursors proliferate and replace normal HSC
- APL: subtype of AML, accumulation of abnormal promyelocytes, bleeding tendency, presence of t(15;17) mutation = PML-RAR-a
What is the diagnosis of APL based on?
- butterfly/bottom cells, and faggot cells
- flow cytometry
- fluorescent probe for chromosome t(15;17) translocation
What is bleeding in APL associated with?
Thrombocytopenia - BM failure
XS coagulation - DIC
Hyperfibrinolysis
What is the treatment for APL?
All-trans-retinoic-acid (ATRA) - drive promyelocytes into mature neutrophils
- gives AML one of the best prognosis
Arsenic tetroxide - induces apoptosis and PML-RAR-a degradation
What are the 4 main causes of angioedema?
- allergic angioedema
- Drug-induced angioedema - ACE inhibitors, statins
- idiopathic angioedema - stress, alcohol, food
- Hereditary angioedema - genetic mutation in C1 esterase inhibitor gene
What are the 3 main categories of drug induced angioedema?
- specific IgE - penicillin, cephalosporin
- Non-specific (intolerance) - NSAIDS
- Kinin-dependent (ACEi, ARBs)
What is the mechanism for angioedema associated with ACE inhibitors?
ACEi block renin/bradykinin pathway - decreased production of AT2 and increased bradykinin levels
Increased bradykinin - permeability and vasodilation
– smoking and ACE induced cough increased risk for this reaction
