Hematology Flashcards
Site of BM aspiration in adults? (1)
Iliac crest (posterior superior)
Tibia may be used for neonate
MCV, MCH, MCHC calculation? (3)
MCV = HCT / RBC
80~100 fL (10^-15 L)
MCH = HB / RBC
27~31 pg (10^-12 g)
MCHC = HB / HCT
32~36 g/dL
In FR, what makes you suspect EDTA Dependent Pseudothrombocytopenia? (2) What is the etiology behind? (1), suggest ways to correct this. (5)
PLT aggregation without fibrin
CA chelation by EDTA exposes PLT antigen, which trigger immune response, causing PLT aggregation
Frequency: 0.1%
Solution:
3 min vortex
Excess EDTA
Kanamycin
Use Plain tube / Citrate tube
Use MgSO4
Why do we use EDTA instead of heparin for CBC? (1)
Heparin acts on antithrombin & thus prevents coagulation, but not PLT aggregation
EDTA acts by CA chelation, preventing both coagulation & PLT aggregation
Effect of sample clot on PT/APTT? (2)
Shorten due to factor activation
Prolong due to factor consumption
What are the effects of underfilling & overfilling EDTA tubes for CBC? (2)
Underfilling causes excess EDTA and thus RBC shrinkage, decreasing HCT
Overfilling causes insufficient EDTA and thus blood clotting
Can I interpret reticulocyte % directly to assess RBC proliferation? (2)
No. Anaemic patient has higher RETIC%, and proliferation is not linear with degree of anemia, so patient HCT & Maturation correction based on that should be account for before interpretation
RI = [(RETIC%*Patient/Normal HCT ratio)] / Maturation Correction
RI > 2 = hyperproliferation (destruction problem)
-AIHA, SCD
RI < 2 = hyperproliferation (production problem)
-CKD, aplastic
When is Osmotic fragility increased / decreased? (2)
Increased in HS
Decreased in SCD / other poikilocytosis
Why do we use Wright-Giemsa for BM but Wright for FR? (2) Why pH 6.8 is critical? (1)
Both uses methylene blue & eosin
Wright-Giemsa is basophilic to facilitate nuclear content inspection, while Wright is relatively eosinophilic
For acidic pH the slide would be eosinophilic, reverse would be basophilic
Why do Heinz Bodies and bite cells exist in G6PD deficient patients? (3) Can we see Heinz bodies in Wright stain? (1)
- Normally, G6PD forms NADPH to reduce H2O2 with Glutathione peroxidase
- G6PD deficiency causes H2O2 accumulation and thus oxidative damage to HB
-Also oxidation of Fe2+ to Fe3+ (Methemoglobin) - Splenic macrophage remove denatured HB, so bite cell is formed
-Absence of bite cell, suspect hyposplenic
Heinz bodies is detected with supravital stain (NMB / BCB)
What is Howell-Jolly’s body? (1) Why does it exist in SCD? (1)
Basophilic nuclear remnant of RBC
Normally removed by splenic macrophages
Exist in cases of hyposplenic (functional hyposplenic in SCD)
What CBC & Chem result would you suspect malaria? (2) Why does a patient with malaria have a fixed interval of fever? (1) How can you tell the difference between different types of Malaria? (5)
Result matching hemolytic anaemia, LR failure, as well as low PLT
Fever occurs during hemolysis, and temporarily stop when invasion of new RBC is completed
falciparum:
>=2 rings, Banana shaped gametocytes
ovale & vivax:
Large infected RBC
malariae:
band form
knowlesi:
>=2 rings, band form
Suggest factors that affect ESR result (3)
Increase: FIB, IgG (MM)
Decrease: anisocytosis, poikilocytosis
When MCHC > 37, what would you do? (3)
MCHC = HB / HCT
Why MCHC is high:
1. Cold agglutinin causes RBC clumping, decreasing HCT
2. Lipaemic causes HB falsely high
3. HS is true MCHC high as spherocyte has smaller cell volume
rule of 3 (RBC3=HB3=HCT) violated:
1. Warm 20min rerun to remove Cold agglutinin
2. Spin down for plasma blanking to compensate for Lipaemic
rule of 3 (RBC3=HB3=HCT) not violated:
1. perform FR, Spherocytosis 3+ suggest HS
2. check for hypoNa induced RBC aggregation causing by altered RBC zeta potential
Why can a patient with high sO2 still be ischemic? (2)
- 2,3 DPG facilitate O2 unloading from HB
When PHOS is Low OR in transfused RBC, 2,3 DPG is deficient, increasing O2 affinity of HB - Oxyhaemoglobin portion is high but O2 delivery is compromised, so tissue hypoxia still occurs
Acidosis also facilitate O2 unloading, so the same condition can occur when patient is having alkalosis
Which leukocyte is in majority in patients with aplastic anemia? (1)
Lymphocyte
In aplastic anemia, pancytopenia (HB,N,PLT) occurs, but lymphoid lineage is less affected.
Why pancytopenia should be reviewed by hematologist? (8)
Pancytopenia can occur in:
1. Sepsis
2. aplastic anaemia
3. megaloblastic anemia (B12 deficiency)
4. S: SLE, SS
5. M: MDS, MM
6. A: AML, ALL
7. P: PNH, PMF (not in PV, ET)
8. splenomegaly caused by cirrhosis induced portal-hypertension
When would you consider an inverted differential to be physiological? (1)
In patient<4y, due to relative neutropenia