Haematological Investigations

Question 1

Possible Causes of misleading results(Pre-collection)

Answer 1

Pre-Collection:
-Physiological: Diurnal vatiation, Physical activity, diet, stress, Posture ,Age and Gender

-Interferences: Smoking, Drugs/Supplements within 8hrs(To be indicated on a form)

Question 2

Possible Causes of misleading results(During-collection)

Answer 2

Interferences:

• Prolonged tourniquet pressure= haemoconcentration
• Haemolysis: Difficult phlebotomy, small needle gauge, excessive negative pressure, High WCC/Pseudohypokalaemia
• Incorrect tube used: wrong anticoagulation-wrong results
• Clotted Sample: Incorrect cell counts
• Lipaemic,haemolysed or jaundiced samples

Question 3

Define what a Full Blood Count(FBC) is

Answer 3

A full blood count gives important information about the haematopoietic cells including; RBCs, WBCs and well as Platelets

Question 4

Define what a Differential count is

Answer 4

A differential count gives a breakdown of the white cell count, including N.M.L.E.B and abnormal cells

Question 5

What happens during the pre-analytics phase

Answer 5

A FBC is performed:

• Venous Blood
• EDTA-Ethylene diamine tetraacetic acid Tube is used which binds the calcium and prevents clotting
• Take to lab,ASAP-Unrelaiable after 24hrs, preferebly<12hrs

Question 6

What are the instruments which are used for the analysis of blood

Answer 6

Automated- ADVIA 2120i

• 150 smaples per hour
• FBC, Differential count, and Reticulocyte count
• If there are any abnormalities manual review of slides is to be done by a pathologist

Question 7

What are the reference ranges which are needed to be compared to to a reference range/internval, to classify a result as normal/abnormal

Answer 7

Reference Interval/Range: A set of values established as normal, maximums or minimums for a given analyte and shows the representation of the normal population in which it is standardized which uses a 95% CI

Question 8

Red Cell Count(RBC)

Answer 8

The number of red blood cells in a volume of blood, x 10^9/L

Question 9

Haemoglobin(Hb)

Answer 9

The amount of haemoglobin in a volume of blood, g/dL

Question 10

Haematocrit(Hct)/Packed Cell Volume

Answer 10

The percentage of red blood cells compared to plasma, %

Question 11

Mean Cell Volume(MCV)

Answer 11

Average volume of the RBC, Hct/RBC, measured in femtolitre(fL)

Question 12

Mean Cell Haemoglobin(MCH)

Answer 12

The average weight of haemoglobin in the RBC, Hb/RBC ,measured in picogram(pg)

Question 13

Mean Cell Haemoglobin Concentration(MCHC)

Answer 13

The average concentration of Hb in the RBC volume, Hb x 1000/MCV x RBC, which is measure in g/dL

Question 14

Red Cell Distribution Width(RDW)

Answer 14

The difference in the size between red cells,%

Question 15

Conditions which will result in a high RBC

Answer 15

Increased red cell production

-Example: Polycythaemia and Thalassaemia

Question 16

Conditions which result in a low RBC

Answer 16

Increased red cell destruction/Loss
-Haemorrhage and Haemolysis

Reduced red cell production

• Haematinic(nutrients needed for rbc development) deficiency
• Bone Marrow disorders

Question 17

Conditions which result in high Hb

Answer 17

High-Polycythaemia(Primary/Secondary causes)

Primary:

• Increased red cell production
• Myeloproliferative disorders

Secondary:

• Increased oxygen demand(Hypoxia): Smoking, prematurity, Resp/Cardiac disorders and Height above sea levels
• Renal disease/tumours
• Exogenous erythropoietin treatment

Artificial: Dehydration

Question 18

Conditions which results in Low Hb

Answer 18

Low- Anaemia

Increased red cell destruction/loss
-Haemorrhage and Heamolysis

Reduced red cell production
-Haematinic deficiency or Bone Marrow disorder

Question 19

Reasons for abnormalities in Haematocrit

Answer 19

Acute blood loss-Unreliable

Shock- RCC Low/Hct normal

Pregnancy-RCC normal/Hct low

Question 20

MCV AND MCH

Answer 20

Macrocytic:
MCV>100fL
Oval/Round

Normochromic/Normocytic

Microcytic,Hypochromic
MCV<83fL, MCH < 27pg
Reduced haem production

Question 21

MCHC

Answer 21

Increased in hereditary spherocytosis

31.5-34.5 g/L

Question 22

RDW

Answer 22

High RDW(>14%)

Macrocytosis: High- Megaloblastic
Normal: Other

Microcytosis: High: Iron deficiency
Normal: Thalassemia

Question 23

Platelet Count

Answer 23

Platelets which are counted by means of an automated machine which gives a reference range of 150-400 x 10^9/L

Question 24

Pseudothrombocytopenia

Answer 24

A false thrombocytopenia which must be verified by a peripheral smear(manually) for a diagnosis

Reasons: Platelet clumping and satellitism-Stick to neutrophils

Question 25

Management of Pseudothrombocytopenia

Answer 25

Platelet Count should be repeated and if clumping still occurs,Repeat FBC in heparin(Green top) or Citrate(Blue top)

Question 26

What is a Thrombocytopenia

Answer 26

A low platelet count of about <150 Causes: -Increased consumption/destruction: Immune mediated -Abnormal distribution: Splenomegaaly -Production: Megakaryopoesis only General bone marrow failure -Dilutional Loss

Question 27

What is a Thrombocytosis

Answer 27

A high platelet count of about >400 Causes -Reactive: Haemorrhage, Infections and Iron Deficiency -Malagnancies: Myeloproliferative neoplasms

Question 28

Leukopenia

Answer 28

Refers to a low total white cell count as the range is 4-11 x 10^9/L Causes: Infections • Most often with viral infections • Sepsis Increased destruction • Autoimmune disorders • Splenomegaly ``` Reduced production • Drugs • Radiation • Bone marrow failure • Nutritional deficiencies • Bone marrow infiltration by malignancy/infection • Congenital ```

Question 29

Leucocytosis

Answer 29

``` Causes: – Haemorrhage – Inflammatory conditions – Haemolysis – Infections – Exercise – Trauma – Surgery – Drugs – Haematological malignancies – Reactive due to non-haematological malignancies ```

Question 30

When does one exclude Leukaemia

Answer 30

If WCC is >30 x 10^9/ L especially when it is associated with Anemia and Low platelets. Do a peripheral smear

Question 31

LEUKAEMOID REACTION

Answer 31

WCC >50 x 109/L Usually reactive, important to do a peripheral smear to confirm ``` Causes: – Infections – Haemorrhage – Drugs – Infections – Diabetic ketoacidosis – Haemolysis – Necrosis / Abscesses / Sepsis – Paraneoplastic syndrome – Asplenia ``` Usually resolve once underlying cause treated,If not, consider a haematological malignancy

Question 32

DIFFERENTIAL COUNT

Answer 32

* 5 part differential count * Absolute values (109/L) preferred ``` – Neutrophils 2.0 – 7.0 – Lymphocytes 1.0 – 3.0 – Monocytes 0.2 – 1.0 – Eosinophils 0.02 – 0.5 – Basophils 0.02 – 0.1 ``` Children: Lymphocytes higher than neutrophils

Question 33

Neutrophilia

Answer 33

Causes: * Bacterial infections * Drugs * Exercise * Trauma / Surgery * Inflammation * Haemorrhage * Haemolysis * Malignancies

Question 34

Neutropenia

Answer 34

Causes: Infections – Most often with viral infections – Sepsis • Increased destruction – Autoimmune disorders – Splenomegaly ``` • Reduced production – Drugs – Radiation – Bone marrow failure – Nutritional deficiencies – Bone marrow infiltration by malignancy/infection – Congenital ```

Question 35

Lymphocytosis

Answer 35

• Viral infections • Chronic bacterial infections • Lymphoproliferative disorders

Question 36

Lymphopenia

Answer 36

``` • Sepsis • Viral infections • Stress • Immunosuppression – Acquired – Inherited • Drugs ```

Question 37

Monocytosis

Answer 37

``` • Chronic infections – Tuberculosis – Brucellosis • Autoimmune disorders • Reactive to malignancies • Certain haematological malignancies ```

Question 38

Monocytopenia

Answer 38

``` • Very rare • As part of general leukopenia • Drugs • Hairy cell leukaemia ```

Question 39

Eosinophilia

Answer 39

Reactive-Drugs,Parasitic infections,Allergies

Question 40

Basophils

Answer 40

Rare Chicken Pox Ulcerative colitis

Question 41

What is a Leukoerythroblastic Reaction Causes:

Answer 41

It is a reaction in which there nucleated red blood cells as well as left shifted granulopoiesis-Immature granulocytes Causes: *Push Out: Bone marrow infiltration-Malignancies,infections *Push In: Bone marrow stress(Severe)-Heamolysis and sepsis

Question 42

Reticulocyte

Answer 42

A young erythrocyte which comes immediatly after extrussion of the nucleus. Contains RNA It reflects bone marrow erythroid activity(In response to an anemia) -Increase release of reticulocyte

Question 43

Increased Reticulocyte count(Marrow stimulation)

Answer 43

Heamorrhage Haemolysis haematinic therapy Polycythaemia Infection Inflammation

Question 44

Decreased reticulocyte count

Answer 44

Haematinic deficinecy Drugs Malnutrition Uraemia