Haematology Flashcards
Causes of relative polycythaemia
- Dehydration
- Diuretics
Causes of true polycythaemia
- EPO or red cell transfusion
- Androgens
- Malignancy - polycythaemia vera
Causes of microcytic anaemia
- Iron deficiency anaemia
- Thalassemia
Causes of normocytic anaemia
- Anaemia of chronic disease
- Bone marrow failure
- Haemodilution (IV fluids)
- EPO insufficiency (renal failure)
Causes of macrocytic anaemia
- Haematinic deficiency (B12 and folate deficiency)
- Haemolysis
- Altered lipid content in red cell membrane e.g. alcohol, liver disease, hypothyroidism, drugs
Iron study results in a patient with iron deficiency anaemia
- Low serum iron AND high transferrin
OR
- Low ferritin
Ferritin levels may be falsely ??? during the acute phase response
Raised
Treatment of a patient with iron deficiency anaemia
PO ferrous sulphate 200mg tads until FBC normal then continue for 3 months to replenish iron stores
When would you consider looking for causes of iron deficiency anaemia?
Iron deficiency in a non-menstruating women - consider upper GI endoscopy and colonoscopy
FBC results in thalassemia
MCV much lower than haemoglobin
Most common cause of normocytic anaemia
Anaemia of chronic disease
Iron study results in a patient with anaemia of chronic disease
- Normal/high ferritin
- Low serum iron
- Low transferrin
Causes of bone marrow failure
- Malignancy e.g. blood cancers
- Drugs e.g. chemotherapy, cytotoxic, antibiotics
- Infection e.g. HIV
- Nutritional
- Radiation
- Poisons
- Congenital
Causes of haematinic deficiency
- Dietary choices e.g. veganism
- Pernicious anaemia (autoimmune destruction of intrinsic factor)
- Ileal disease e.g. Crohn’s
Treatment of haematinic deficiency
- Folate: oral replacement
- B12: IM injections
Never replace ??? before checking ??? is normal as this can precipitate subacute combined degeneration of the spinal cord
- Folate
- B12
Causes of haemolysis
- Sickle cell disease
- Thalassemia
- GPD6 deficiency
- Hereditary spherocytosis
- Autoimmune haemolysis
- Haemolytic transfusion reaction
- DIC
- Eclampsia
- Malaria
- Toxins
Clinical features of haemolysis
- Signs of anaemia
- Jaundice
- Dark urine/pale stool
- Splenomegaly (chronic)
Investigations which would indicate haemolysis is occurring
- FBC: macrocytic anaemia, Reticulocyte response, increased LDH
- LFTs: unconjugated bilirubinaemia
- Consumption of haptoglobin
Investigations to perform to work out cause of haemolysis
- Blood film
- Coomb’s test
Commonest inherited single gene conditions
Haemoglobinopathies
Pathophysiology of sickle cell disease
Single nucleic acid substitution (GAG to GTG) in the beta global gene leading to synthesis of structurally abnormal haemoglobin.
This causes HbS to polymerise and form crystals when it becomes deoxygenated at low oxygen tensions, causing haemoglobin to clump and become ‘sickled’ in shape, meaning RBCs are much more easily damaged in the capillaries.
Originally the sickling is reversible but becomes irreversible over time.
Inheritance pattern of sickle cell disease
Autosomal recessive
Factors which increase sickling of RBC in sickle cell disease
- Hypoxia
- Infection
- Acidosis
- Cold temperatures
- Medications e.g. ibuprofen
- Low levels of HbF (higher levels are protective)
Clinical features & investigation results of a patient with sickle cell TRAIT
- Asymptomatic
- Normal FBC (no anaemia)
- Normal blood film
- Abnormal HbS detected on HPLC (HbA and HbS)
Treatment required in sickle cell trait
None - patient’s are asymptomatic and don’t experience anaemia
What are the two main complications of sickle cell disease?
1) Chronic haemolytic anaemia (due to damage and breakdown of RBCs) - Hb 70-90g/l
- leads to jaundice and bilirubinaemia
- leads to reticulocytosis (as bone marrow try to compensate for anaemia)
2) Acute faso-occlusive crisis
- often presents with bony pain
Acute complications of sickle cell disease
- Infection
- Acute anaemia - splenic/hepatic sequestration, aplastic crisis (associated with parvovirus), haemolytic crisis
- Chest crisis
- Stroke
- Priapism
- Avascular necrosis of the hip or shoulder
Management of complications in sickle cell disease
- Infection - prophylactic penicillin and vaccinations
- Stroke - chronic transfusion in high risk patients
- Avoid precipitating factors e.g. cold, excessive exercise, dehydration
- Crisis prevention, analgesia and supportive care
- Transfusion - intermittent top up transfusion or exchange transfusion (to reduce HbS%) OR chronic transfusion and chelation
- Hydroxycarbamide (increases HbF%)
- Bone marrow transplant (curative)
Chronic complications of sickle cell disease
- Chronic anaemia
- End-organ damage e.g. renal failure, pulmonary hypertension, cerebrovascular disease, heart failure, splenic atrophy
- Immunocompromise and increased risk of infection with encapsulated organisms
- Transfusion-related complications e.g. iron overload, allo-antibody formation
How would you detect HbS in a patient with suspected sickle cell disease?
HPLC
Management of a painful vaso-occlusive episode in a patient with sickle cell disease
- Adequate pain control within 60 mins of presentation e.g. IV morphine
- Ensure adequate hydration e.g. IV fluids
- Avoid/treat hypoxia e.g. oxygen
- Examine/investigate for/treat infection e.g. antibiotics
How are newborns screened for sickle cell disease?
Guthrie heel prick test
Current life expectancy in sickle cell disease
50-60 years
Pathophysiology of thalassemia
Reduced rate of normal beta globin chain synthesis
If a patient has 1 or 2 abnormal alpha globin genes they will have …?
Alpha thalassemia trait
If a patient has 3 or 4 abnormal alpha globin genes they will have…?
Alpha thalassemia major (not usually compatible with life)
If a patient has 1 abnormal beta globin gene they will have…?
Beta thalassemia trait
If a patient has 2 abnormal beta globin genes they will have…?
Beta thalassemia major
Risk factors for thalassemia trait
- Family history
- Ethnicity
Investigation results in a patient with alpha thalassemia trait
- Mild anaemia or no anaemia
- Normal HPLC
- Normal ferritin
Alpha thalssemia trait is a diagnosis of exclusion.
Investigation results in a patient with beta thalassemia trait
- Anaemia
- Elevated HbA2
- Normal ferritin
- Very low MCV
Clinical features and investigation results in a patient with beta thalassemia major
- Splenomegaly
- Bony changes (e.g. skull bossing)
- Failure to thrive
- Jaundice
- Gallstones
- Severe hypochromic microcytic anaemia
- Increased reticulocytes
- HPLC: elevated HbA2, HbF and reduced HbA
Management of a patient with beta thalassemia trait
None needed if patient asymptomatic (avoid unnecessary iron supplementation)
Management of a patient with beta thalassemia major
- Chronic transfusions + chelation therapy
- Bone marrow transplant
Complications of beta thalassemia major
- Iron overload - leads to cardiac failure, liver failure, endocrine problems e.g. diabetes
- Allo-antibody formation
Current life expectancy for patients with beta thalassemia major
40-50 years
Commonest severe inherited bleeding disorder
Haemophilia
Inheritance pattern of haemophilia
X-linked recessive - carrier mothers have a 50% chance of each son being affected and each daughter being a carrier
Factor affected in Haemophilia A
Factor VIII
Factor affected in Haemophilia B
Factor IX
Investigation results in a patient with Haemophilia
- Isolated prolonged APTT (factors VIII and IX both part of intrinsic pathway)
- Normal PT
- Normal fibrinogen
Clinical features in a patient with haemophilia
- Family history e.g. carrier mother, history of bleeding problems on haemostatic challenges
- Birth history of bleeding on delivery
- Prolonged bleeding, re-bleeding or excess bruising
- Unusual surgical bleeding
- Bleeding with IM injections, vaccinations or heel prick test
Categories of haemophilia
- <1% factor VIII/IX = severe
- 1-5 factor VIII/IX = moderate
- 6-49% factor VIII/IX = mild
(50-150% = normal)
Symptoms of mild haemophilia
- Bleeding with surgery or dental work
- Bleeding with major trauma
Symptoms of moderate haemophilia
- Bleeding with minor trauma - SC or IM bleeds
- Occasionally spontaneous bleeds
Symptoms of severe haemophilia
- Recurrent spontaneous joint bleeds leading to joint damage
- Spontaneous intra-cranial bleeds
Management of haemophilia
Recombinant synthetic factor VIII or IX
Tranexamic acid
Physiotherapy
Commonest inherited bleeding disorder
Von Willebrand disease
Clinical features of von Willebrand disease
- Mucosal bleeding
- Easy bruising
- Dental bleeding
- Epistaxis
- Menorrhagia
- Surgical and post-traumatic bleeding
Malignant cells in leukaemia are???
Blasts/haematopoetic stem cells/early progenitor cells (acute leukaemia) or myeloid cells or lymphocytes (chronic leukaemia)
Clinical features of acute leukaemia
- Symptoms onset over days-weeks
- Bone marrow failure symptoms e.g. anaemia, bleeding, infection
- Hepatomegaly
- Splenomegaly
- Lymphadenopathy
Investigation results in acute leukaemia
- Blasts seen in blood
Clinical features of chronic leukaemia
- Symptoms onset over months-year
- Hepatomegaly
- Splenomegaly
- Lymphadenopathy
Investigation results in chronic leukaemia
- Leucocytosis
Laboratory definition of leukaemia
> 20% blasts seen in bone marrow
Pathological hallmark of AML
Auer rods
Clinical features of AML
- Most common acute leukaemia in adults
- Middle-aged to elderly patients
- Short clinical history
- Bone marrow failure symptoms
- Infiltrates in liver, spleen and other tissue
Investigation results in AML
- WCC elevated or reduced
- Coagulation disorders
Clinical features of ALL
- Most common childhood malignancy
- Children affected
- Short clinical history
- Bone marrow failure symptoms
- Infiltrates in lymph nodes, bone, liver, spleen and CNS
Investigation results in ALL
- WCC elevated or reduced
Investigations to consider in a patient with suspected leukaemia
- Urgent FBC - will be abnormal
AML/ALL: pancytopenia +/- circulating blasts
CML: neutrophils and myeloid precursors
CLL: lymphocytes - Blood film to look for circulating malignant cells
- Urgent coagulation screen
Diagnostic test for leukaemia
Bone marrow aspirate and trephine from the posterior iliac crest
Can also do bone marrow examination under the microscope
Can do immunophenotyping to determine antigens on cell surface
Can do cytogenetic analysis to determine any genetic causes e.g. trisomy 8 (only present in blood cells)
Management of leukaemia
- Chemotherapy - intensive regimes with multiple drugs, oral, IV or IT
- Stem cell transplantation - allogenic transplant from sibling or unrelated donor
- Monoclonal antibodies - Imatinib targeted at Philadelphia chromosome in CML
- Supportive care e.g. Infection prophylaxis and treatment Blood transfusion - red cells or platelets Coagulopathy management Central venous access
Clinical features and investigation results for a patient with CML
- Age 40-60
- Abdominal discomfort
- Splenomegaly
- Very high WCC - mostly neutrophils and precursors
- Hyperviscosity - mucosal bleeding, shortness of breath, visual changes, neurological symptoms
Definitions of lymphomas
Malignancy of lymphocytes (T or B cells) in the lymph glands and other tissues
Pathological hallmark of Hodgkin’s lymphoma
Reed-Sternberg cells
Most common haematological malignancy
Non-Hodgkin’s lymphoma
Clinical features of Hodgkin’s lymphoma
- Young adults and >50s
- More common in men
- Very aggressive symptoms
- Asymmetrical painless superficial lymphadenopathy (usually cervical)
- Organomegaly
- Constitutional symptoms e.g. drenching night sweats, fever, weight loss, itch
- Alcohol induced nodal pain
Clinical features of Non-Hodgkin’s lymphoma
- 55-60 year olds
- Varying clinical course
- Lymphadenopathy
- Organomegaly
- Constitutional symptoms e.g. drenching night sweats, weight loss, fever, itch
- Extra-nodal involvement more common
Features of pathological lymphadenopathy
- > 1cm in size
- Persistant
- Painless
- No reactive cause
- Rubbery/matted texture
FBC results in lymphoma
May be NORMAL - will only be abnormal if bone marrow is involved
Diagnostic test for lymphoma
Lymph gland biopsy
Lymphoma management
- Watchful waiting
- Chemotherapy e.g. CHOP therapy
- Targeted therapies e.g. Rituximab
Pathophysiology of multiple myeloma
Malignant proliferation of plasma cells within the bone marrow - these plasma cells secrete antibodies (para-proteins)
Main risk factor for multiple myeloma
Age