Interpreting Full blood count

Question 1

If you suspect a drop in Hb is due to fluids causing a dilutional effect what other full blood count element is useful and what would it show?

Answer 1

Look at the haematocrit, this shows the percentage of the total blood volume accounted for by red blood cells

Question 2

What are the causes of macrocytic anaemia?

Answer 2

B12 and folate deficiency

Alcohol

Question 3

What are the causes of normocytic anaemia?

Answer 3

Acute blood loss
haemolytic anaemia
Renal failure (decreased erythropoietin)

Question 4

What are the causes of microcytic anaemia?

Answer 4

TAILS
Thalassaemia
Anaemia of chronic disease
Iron deficiency
Lead poisoning
Sideroblastic anaemia

Question 5

What are the causes of iron deficiency anaemia?

Answer 5

Chronic blood loss e.g. from GI tract malignancy/bleed
Increased demand e.g. pregnancy/growth
Decreased uptake e.g. coeliac disease, gastrectomy
Poor intake

Question 6

What are the causes of B12 deficiency anaemia?

Answer 6

Pernicious anaemia e.g. no intrinsic fator to bind to b12 and allow it to be absorbed
malabsorption
Strict veganism

Question 7

What are the causes of folate deciciency anaemia?

Answer 7

Dietary (alcoholism, neglect)
Increased demant e.g. pregnancy, growth
Decreased absorption e.g. coeliac, gastrectomy, pancreatic insufficiency

Question 8

What should be treated first B12 or folate deficiency?

Answer 8

Treat in alphabetical order, B12 prevents subacute cord degeneration

Question 9

What is the pathophysiology behind anaemia of chronic disease?

Answer 9

Inflammatory cytokines reduce the ability of the bone marrow to respond to erythropoetin
Also reduces cellular iron release so tranferrin saturation decreases

Question 10

What are the causes of haemolytic anaemia?

Answer 10

Inherited: sickle, thalassaemia
Aquired: drug induced, autoimmune haemolytic anaemia
Disseminated intravascular coagulation
thrombotic thrombocytopenic purpura

Question 11

What investigations should be done for haemolytic anaemia?

Answer 11

Blood film - schistocytes (microangiopathic haemolytic anaemias), inclusion bodies (malaria), spherocytes (hereditary spherocytosis)

Question 12

What are the causes of polycythaemia?

Answer 12

Relative (decreased plasma volume):
-acute dehydration
-Chronic associated with obesity and hypertension
Absolute (increased RBCs)
-Primary - polycythaemia rubra vera
-Secondary - increased erythropeitin e.g. COPD, altitude

Question 13

What investigations should be done if polycythaemia rubra vera is suspected?

Answer 13

Will be raised WCC and platelets

Request JAK 2 mutation testing and bone marrow biopsy

Question 14

What are the causes of high and low lymphocyte counts?

Answer 14

High:
-Viral infection
-Chronic infection
-Chronic lymphocytic leukaemia
-Lymphomas
Low:
-Viral infection
-HIV
-Post chemo
-Bone marrow failure (leukaemia/lymphoma)

Question 15

What are the causes of high/low neutrophil counts?

Answer 15

High:
-Bacterial infection
-Inflammation
-Necrosis
-Corticosteroids
-Malignancy
-Chronic myeloid leukaemia
Low:
-Post chemo
-Drugs (4C's Carbamezapine, Clozapine, carbimazole, colchicine)
-Viral infection
-Bone marrow failure

Question 16

What are the causes of high/low monocytes?

Answer 16

High:
-Some infections e.g. TB, malaria, typhoid
-Autoimmune diseases
-Leukaemias
-Chronic inflammation
Low:
-Acute infections
-Steroids
-Post chemo

Question 17

What are the causes of high eosinophil count?

Answer 17

Allergic reactions
Parasitic infections
Drug reactions

Question 18

What are the causes of raised basophil count?

Answer 18

igE mediated hypersensitivity
Inflammatory disorders
Viral infection
CML

Question 19

What are the causes of thrombocytopenia?

Answer 19

Decreased production: bone marrow infiltration, aplastic anaemia, myelosuppression
Increased destruction/consumption:
-Non-immune - DIC, TTP, haemolytic uraemic syndrome
-Primary immune - idiopathic thrombocytopenic purpura
-Secondary immune - SLE, chronic lymphocytic leukaemia

Question 20

What investigations should be do for thrombocytopenia?

Answer 20

Blood film with bone marrow biopsy
Infection sceen e.g. HIV, hep C
LFTs
lactate dehydrogenase - raised in haemolysis
B12 and folate levels
Coag screen if DIC suspected

Question 21

What is the treatment of idiopathic thrombocytopenic purpura?

Answer 21

Observation
Corticosteroids
IV immunoglobulins
Platelet trasfusion if bleeding

Question 22

When should platelet be given for thrombocytopenia?

Answer 22

When the platelets are less than 10x10^9 or less than 50x10^9 and bleeding

Question 23

What are the causes of thrombocytosis?

Answer 23

Primary - essential thrombocythemia, myeloproliferative disorders
Secondary (reactive) - bleeding, inflammation, infection

Question 24

What is the treatment of thrombocytosis?

Answer 24

Aspirin to prevent thrombus

Hydroxycarbamide (if primary cause)

Question 25

What are the causes of pancytopenia?

Answer 25

bone marrow infiltration - leukaemia, myeloma, lymphoma, myelofibrosis
Myelosupression - drugs, chemo, lead, infection (HIV)
Impaired haematopoiesis - vit B12/folate deficiency, aplastic anaemia, myelodysplastic syndrome
Peripheral destruction of blood cells