Interpreting Lab Results

Front 1

Normal range Hb

Back 1

g/l
140-180 Male
120-16- female

Front 2

Normal range RBCs

Back 2

Male4.7-5.5 x10^12/L
Female 4.2-4.9 x10^12/L

Front 3

Normal range WBCs

Back 3

(x10^9/L)
Male 4500-11000
Female 45000 11000

Front 4

Haematocrit normal range

Back 4

%
Male 40-54
Female 37-47

Front 5

MCV normal range

Back 5

fL
80-100

Front 6

MCH normal range

Back 6

27-31pg
Mean corpuscular Hb

Front 7

MCHC normal range

Back 7

33-37%
Mean corpuscular Hb concentration

Front 8

Platelets normal range

Back 8

150 000-450 000/uL

Front 9

RDW normal range
and definition

Back 9

11.5-14.5
Red cell distribution width - size or volume of red cells

Front 10

What are the causes of increased Hb?

Back 10

• Primary polycythemia (i.e. polycythemia rubra vera)
• Secondary polycythemia due to
1. Reduced fluid intake or excess fluid loss
2. Congenital and acquired heart disease
3. Lung disease, high altitudes, heavy smokers
4. Tumours, e.g. renal cell carcinoma, hepatoma
5. Renal cysts

Front 11

What are the causes of decreased Hb?

Back 11

• Acute or chronic blood loss
• Anaemia, e.g. iron deficiency anaemia, sickle cell anaemia, megaloblastic anaemia (due to folate or B12 deficiency) etc…
• Haemolysis
• Dilutional, e.g. fluid overload

Front 12

What is haematocrit?

Back 12

• Haematocrit is the percentage of Hb present on the RBCs
• Thus it is directly related to the Hb concentration
• Hence the causes of increased haematocrit or decreased haematocrit is the same as those of Hb

Front 13

What are the causes of increased platelets?

Back 13

• Sudden exercise
• After trauma or surgery (esp. splenectomy)
• Acute haemorrhage
• Bone fracture
• Primary thrombocythaemia
• Leukaemias or other myeloproliferative disorders

Front 14

What are the causes of reduced platelets?

Back 14

• Disseminated intravascular coagulation (DIC)
• Idiopathic thrombocytopaenia purpura (ITP)
• Thrombotic thombocytopaenia purpura
• Marrow suppression, due to chemotherapy, thiazide diuretics, alcohol, leikaemias, aplastic anaemias
• Hypersplenism

Front 15

You are called to see a 73yo patient with unstable angina. His admission laboratory results reveal a platelet count of 32,000/uL. Discuss your initial approach

Back 15

• This is low platelets, and the reasons could be
1. Pseudothrombocytopaenia
2. Decreased production, e.g. infiltrative processes, myelodysplasia (i.e. preleukemic syndrome), drugs (e.g. chemotherapy), radiation, malnutrition (esp. vitB12 and folate deficiency)
3. Peripheral destruction, e.g. ITP, drugs, SLE, Infection, snake bits, bruns, GN, etc…
4. Hypersplenism
• Immediate assessment
1. Is the patient bleeding – remember risk of bleeding increases with platelet count of <50,000/uL; risk of spontaneous bleeding increases with count < 20,00/uL
2. Is there a past history of low platelet count, i.e. is it acute problem (e.g. ITP) or chronic (suggesting cirrhosis, hypersplenism)
3. What is the patient’s medication history – esp. alcohol, sulfonamides, heparin, gold, thiazide diuretics, cimetidine and captopril
4. Is there a history of a preceding viral infection?

Front 16

What is MCV and why does it matter anyway?

Back 16

• MCV is mean cell (or corpuscular) volume
• It is the measure of the average volume of RBCs
• It is increased in megaloblastic anaemia (B12, folate deficiency), macrocytosis (normoblastic) anaemia, reticulocytosis, Down’s syndrome, and chronic liver disease
• It is decreased in iron deficiency anaemia, thalassemia, some cases of lead poisoning

Front 17

What is HCHM and why does it matter?

Back 17

• This is the average concentration of Hb in a given volume of RBCs
• It is calculated by Hb/haematocrit
• It is increased in very severe and prolonged dehydration or spherocytosis
• It is decreased in iron deficiency anaemia, overhydration, thalassemia and sideroblastic anaemia

Front 18

What is RDW and why do we care about it?

Back 18

• It is a measure of the degree of anisocytosis (variation in RBC size)
• It is measured by the automated haematology counters
• It is increased in many anaemias, esp. macrocytic anaemia

Front 19

What is WCC?

Back 19

• This is white cell count
• It is increased in infections (esp. bacterial), leukaemia, leukaemoid reactions, tissue necrosis, postsplenectomy, exercise, fever, pain, anaesthesia and labour
• It is decreased in sepsis, overwhelming bacterial infections, certain nonbacterial infections (e.g. influenza, hepatitis, mononucleosis), aplastic anaemia, pernicious anaemia, hypersplenism, cachexia, chemotherapy, and radiotherapy

Front 20

When we talk about white cell differentials, what does this comprise of?

Back 20

• Basophils
• Eosinophils
• Lymphocytes
• Monocytes and
• Neutrophils

Front 21

Tell me about basophils

Back 21

• When it is increased, think of chronic myeloid leukaemia, rarely in recovery from infection and from hypothyroidism
• When it is decreased, think of acute rheumatic fever, lobar pneumonia, after steroid therapy, thyrotoxicosis, and stress

Front 22

What about eosinophils?

Back 22

• When it is increased, this means allergy, parasitic infections, skin diseases, malignancy, drugs, asthma, etc…
• When it is decreased, think of post steroids, adrenocorticotropic hormone (ACTH), after stress (e.g. infection, trauma, burns) and Cushing’s syndrome

Front 23

What can you tell me about lymphocytes?

Back 23

• When it is increased, think of infections (e.g. AIDs, measles, German measles, mumps, etc…)
• When it is decreased, this could be normal (in 22% of population) or stress, burns, trauma, uaemia, some viral infectiosn, bone marrow suppression from chemotherapy and steroids

Front 24

You receive a FBE results back, and it reveals increased monocytes. What do you think?

Back 24

• Bacterial infection, e.g. TB, subacute bacterial endocarditis, brucellosis, typhoid, recovery from acute infection
• Protozoal infection
• Infectious mononucleosis
• Others, e.g. leukaemia, Hodgkin’s disease, etc..

Front 25

What are the causes of increased neutrophils counts?

Back 25

• Physiological, e.g. severe exercise, last months of pregnancy, labour, surgery, newborns, steroid therapy
• Pathological, e.g. bacterial infections, non-infective tissue damage (e.g. AMI, pulmonary infarction, crush injury, burn injury), metabolic disorders (e.g. eclampsia, DKA, acute gout)

Front 26

What are the causes of decreased neutrophil counts?

Back 26

• Pancytopenia, aplastic anaemia, PMN depression (a mild decrease is referred to as neutropenia, severe is called agranulocytosis)
• Marrow damage (chemotherapy)
• Severe overwhelming infections, e.g. disseminated TB, sepsis