Anaemia

Best differentiating factor between Normocytic anaemias

Reticulocyte count

What is Reticulocyte count a measure of

Measure of marrow response to anaemia

Name 2 conditions that would → normocytic anaemia with high reticulocytes

Name 3 conditions that would → normocytic anaemia with low/normal reticulocytes

Further testing done with normocytic anaemia

Blood film

Renal function

Haemolysis screen

Haematinics

Bone marrow aspirate

What leads to Haemolytic Anaemia

Red cell destruction that the bone marrow doesn’t compensate for

Reticulocyte levels in haemolysis are high/low

High

Name 3 intrinsic (inherited) causes of haemolysis

▪ Membrane Defects

▪ Haemoglobinopathies (sickle cell disease..)

▪ Enzyme Deficiencies

Name 4 extrinsic (acquired) causes of haemolysis

▪ Immune Haemolysis

▪ Microangiopathic Haemolysis

▪ Infections: Malaria

▪ Medications

Haemolysis can be intra/extravascular. Give 2 intravascular & 1 extravascular cause

Intravascular: Mechanical – Heart Valve / Paroxysmal Nocturnal Haemoglobinuria

Extravascular: Spleen

Signs we test for to show Haemolysis

Evidence of Marrow response:

• Reticulocytosis / Polychromasia

Look for breakdown products:

• Unconjugated Bilirubin ↑

• Lactate Dehydrogenase ↑

Free Haemoglobin in Plasma or Urine

• Haptoglobin ↓

• Urinary Haemosiderin/ Urobilinogen +

Abnormal Red Blood Cells:

• Blood film: Spherocytes, Sickle cells, Red Cell Fragments

Evidence for specific types of haemolysis:

• Direct Coombs = Direct Antiglobulin Test

Write in an up/down arrow

Describe how membrane defects can cause Intrinsic Haemolytic Anaemias

The normal RBC membrane has two important types of interactions:

- Vertical interactions: attach the internal protein skeleton to the lipid bilayer (outer membrane).

- Horizontal interactions: connect proteins within the internal skeleton, providing strength and stability.

Defective vertical interactions → membrane detaches and is lost → hereditary spherocytosis (HS).

Defective horizontal interactions → skeleton loses strength → hereditary elliptocytosis (HE) or, if severe, hereditary pyropoikilocytosis (HPP).

Prevalence of Hereditary Spherocytosis in Caucasians

1/1000 to 1/3000

Inheritance pattern of Hereditary Spherocytosis

AD

Mutations in Hereditary Spherocytosis

Band 3/ Spectrin/ Actin/ Ankyrin

Pathogenesis of Hereditary Spherocytosis

Mutations in Band 3/ Spectrin/ Actin/ Ankyrin → Loss of membrane support → Spherocyte shape (less deformable) → Prematurely destroyed in the spleen

Symptoms of Hereditary Spherocytosis

Asymptomatic, Anaemia, Jaundice

What 3 things would point you to suspect Hereditary Spherocytosis

Haemolysis

Spherocytes

May have family history

Test to confirm diagnosis of Hereditary Spherocytosis

Eosin-5-maleimide (EMA) binding assay

Hereditary Spherocytosis treatment

Folic acid

Management of gall stones

Monitor for Aplastic Crisis

Splenectomy if severe

Inherited/ Intrinsic Haemolytic Anaemias can also come from enzyme deficiencies. What 2 processes do they affect & explain outcome

Pyruvate Kinase (PK) Deficiency → Defects in glycolysis → Inability to meet energy needs of the cell and shortened cell lifespan

Glucose-6-phosphate

Dehydrogenase (G6PD) deficiency → Defects in the Pentose Shunt → Susceptibility to oxidative stresses & formation of Methaemoglobin

Which of the 2 enzyme deficiencies is more common

Glucose-6-phosphate dehydrogenase (G6PD) deficiency (pentose)

Outcome of Pyruvate Kinase (PK) Deficiency

Chronic Haemolysis

Treatment for Pyruvate Kinase (PK) Deficiency

Splenectomy may be needed in severe cases.

Blood film features (2) of Pyruvate Kinase (PK) Deficiency

Polychromasia

Spheroacanthocytes / ‘prickle cells

Inheritance pattern of Glucose-6-phosphate dehydrogenase (G6PD) deficiency

X-Linked Recessive

Risk factors for Glucose-6-phosphate dehydrogenase (G6PD) deficiency

Male (X-Linked Recessive inheritance)

Mediterranean & Afro-Caribbean ethnicity

Haemolysis Triggers - Infection, broad beans, medications (dapsone)

Sx of Glucose-6-phosphate dehydrogenase (G6PD) deficiency

Neonatal jaundice

Acute episodic haemolysis

How is Glucose-6-phosphate dehydrogenase (G6PD) deficiency diagnosed

Clinical

Blood Film (during episode)

Confirmatory assay for G6PD activity outside acute event

Blood film feature of G6PD Deficiency

Bite cells

Spherocytes

(Heinz beans - risk factor = broad beans)

How does G6PD Deficiency → Heinz bodies, Bite cells & Spherocytes

What can lead to Antibody mediated red cell destruction

• Allo-antibodies (e.g. Transfusion reactions)

• Autoimmune Haemolytic Anaemia

How can Autoimmune Haemolytic Anaemia be classified

Primary vs Secondary (SLE, Rheumatoid Arthritis, CLL..)

Warm vs Cold (according to the temperature at which antibodies react)

Name 2 drugs that can induce Autoimmune Haemolytic Anaemia

Penicillin

Quinidine

What happens in Autoimmune Haemolytic Anaemia

Antibody coated red cells are consumed in the spleen & lose membrane to form Spherocytes

2 tests to diagnose Autoimmune Haemolytic Anaemia

Haemolysis

Positive Direct Antiglobulin (Coombs) Test

Treatment for Autoimmune Haemolytic Anaemia

Immunosuppression: Steroids, Rituximab.

Splenectomy (rare)

How is a Direct antiglobulin test (Coombs Test) done

What is Microangiopathic Haemolysis

Destruction of red cells due to abnormalities in small vessels

How does Microangiopathic Haemolysis present on a blood film

Red cell Fragmentation

3 causes of Microangiopathic Haemolysis

– Haemolytic Uraemic Syndrome (HUS)

– Thrombotic Thrombocytopenic Purpura (TTP)

– Disseminated Intravascular Coagulation

During what phase of malaria is Haemolysis seen most

Haemolysis particularly with Falciparum & High Parasite loads during erythrocytic phase of illness

How is Haemolytic Anaemias of infections/malaria similar to anaemia of chronic disease

Hepcidin

Is the connection between anaemia & kidney function strong

Yes! 90% of patients with GFR <25 are Anaemic

New unexplained Anaemia + Renal Failure points towards what

Myeloma

4 features of Renal Failure Associated with Multifactorial anaemia

• Inadequate EPO

• Uraemia – mild haemolysis

• Blood Loss (e.g. Haemodialysis)

• Secondary Hyperparathyroidism

Treatment for Renal Failure Associated Multifactorial anaemia

• Treat underlying cause

• rEPO in some cases

• Ensure iron replete (Ferritin unreliable)

Sign of Marrow Failure

Pancytopenia

If marrow failure is caused by malignancy, what will show a blood film

Blast cells

If marrow failure is caused by Fibrosis / infiltration, what will show a blood film

Teardrop cells

How is marrow failure diagnosed

Bone marrow aspirate

Name a virus that can cause anaemia

Parvovirus B19 / Erythrovirus B19

How does Parvovirus B19 / Erythrovirus B19 usually present

Slapped cheek syndrome in children

Transient arthritis or asymptomatic in adults

85% of elderly persons have serological evidence of past infection

When would Parvovirus B19 / Erythrovirus B19 cause symptomatic anaemia

In Immunosuppression or Chronic Haemolysis

7 tests to do in a Macrocytosis Work-Up

• Reticulocyte Count

• Blood Film (Megaloblastic, MDS Changes)

• Vitamin B12 and Folate levels

• TFT’s

• Liver Function Tests

• +/- Haemolysis screen

• +/- Bone Marrow Biopsy

Megaloblastic anaemia cause

Impaired DNA production

Megaloblastic Anaemias characteristic feature

Characteristic Bone Marrow Appearance

How do B12 & folate affect DNA

What happens if you consume too much B12

Body stores B12 in excess

Absorption of B12 requires what 4 conditions

Functioning:

Salivary Proteins (haptocorrin – protects B12 from stomach acid)

Stomach (Acid + Parietal cells - Intrinsic Factor)

Pancreas (Calcium Supply)

Small Intestine (Absorption of B12-IF Complexes)

Causes of Vitamin B12 Deficiency

Dietary - Vegan diet

Gastric Causes

• Pernicious Anaemia

  • Autoimmune gastritis leads to deficiency in stomach acid + IF (IM replacement vs high dose oral replacement)

  • Antibodies detectable to gastric parietal cells, intrinsic factor (most specific)

Atrophic Gastritis - Loss of acid production only, may still absorb free Vitamin B12 from supplements

Gastrectomy

Medications:

• Proton Pump Inhibitors / Antacids

• Metformin

• Nitrous oxide

Pancreatic Insufficiency

Small Bowel

• Coeliac Disease

• Crohn’s Disease

Sx of Vitamin B12 Deficiency

Symptoms of Anaemia

Neurological Symptoms

• Peripheral Neuropathy

• Subacute combined degeneration of the cord

• Dementia

Glossitis

Macrocytosis / Anaemia

Pancytopenia if Severe

Raised LDH (destruction of red cells)

Causes of folic acid deficiency

Dietary Deficiency

• Alcoholism

• Elderly (“tea and toast” diet)

• Total Parenteral Nutrition

Malabsorption

• Coeliac disease

• Crohn’s disease

Increased Demand

• Pregnancy (Neural Tube Defect Risk)

• Growth spurts

• Chronic Haemolysis

• Haemodialysis

Clinical features / Sx of folic acid deficiency

• Haematologic features similar to B12 deficiency

• No neurological disturbance

• Mild jaundice (ineffective red cell production & haemolysis)

• May have features of Haemolytic anaemia if due to increased requirements

What B12 & folate levels are considered deficiencies

B12 <125

Folate <2

What is considered between 125-300 B12 & 2-4 Folate

Indeterminate

• Red Cell Folate (more specific)

• Methylmalonic Acid Levels (raised only in B12 deficiency)

• Clinical context

• Trial of Tx

• Consider other causes

Folate Deficiency treatment

• PO Folate 5mg Orally

• Consider need for B12 replacement

• Consider underlying cause

B12 Deficiency treatment

• Usually parenteral B12 (Intramuscular)

• Neurological symptoms generally resolve

• Consider underlying cause..

• Lifelong replacement required for Pernicious Anaemia

When anaemia is present with Folate & B12 deficiency and you give treatment, what is a marker of response to Tx

Treatment should lead to reticulocytosis

3 Causes of macrocytosis

Alcohol Excess (most common)

Liver disease

Hypothyroidism (rare)

3 causes of Non-Megaloblastic anaemia

– Liver disease

– Myelodysplastic Syndrome

– Alcoholism

What is Myelodysplastic Syndrome (MDS)

Spectrum of Malignant Bone Marrow Disorders that → Ineffective / Abnormal blood cell production

Blood features of Myelodysplastic Syndrome (MDS)

Low blood counts:

• RBC: fatigue

• WBC: infection

• Plt: bleeding

Risk associated with Myelodysplastic Syndrome (MDS)

Risk of transformation / Progression to Acute Leukaemia (AML)

Differentiate between Thalassaemia vs Haemoglobinopathy

Where in the world are thalassaemia / sickle cell anaemia seen

What is wrong in Thalassaemias

Impairment of production of one globin chain leads to

• Reduced Haemoglobin (microcytosis)

• Imbalance, precipitates of excess globin chains, red cell damage + Haemolysis

How would anaemia develop from Thalassaemias

In milder forms of thalassaemias, increased RBC production can compensate, but in more severe forms anaemia develops

What is Beta Thalassaemia trait

Heterozygosity for Beta Thalassaemia gene

Presentation of Beta Thalassaemia trait

Microcytosis without Anaemia

How is Beta Thalassaemia trait diagnosed

Haemoglobin analysis - Increased Hb A2 (2α + 2δ)

What is Beta Thalassaemia Major

Homozygosity for βo or β+

Clinical severity of Beta Thalassemia Major

Severe

What actually happens in Beta Thalassemia Major

Failure of HbA to take over

Beta Thalassemia Major leads to

Expanded, ineffective haematopoiesis → Transfusion dependent anaemia

Describe Beta Thalassemia Major blood film

Treatment for Beta Thalassaemia Major

Transfusion Support

Management of Iron Overload

Bone Marrow Transplant

Outcome of Alpha Thalassaemia with 1-2 gene deletion

• Microcytosis

• Asymptomatic

Outcome of Alpha Thalassaemia with 3 gene deletions

• ‘Haemoglobin H Disease’

• Microcytic anaemia

• Haemolysis and Splenomegaly

Outcome of Alpha Thalassaemia with 4 gene deletions

• Homozygous for α0

• Haemoglobin Barts / Hydrops Fetalis

• Non-functional Hb Barts (4γ chains)

• Fatal in utero or in neonatal period

Name Haemoglobinopathies associated with Africa & SE Asia (separateley)

Haemoglobin S & C (African ancestry)

Haemoglobin E (SE Asia)

Most severe Haemoglobinopathy

Haemoglobin S

Haemoglobin S Haemoglobinopathy →

Sickle Cell Disease

S Haemoglobinopathy mutation

Glu -> Val

When is Haemoglobin S insoluble

Insoluble at concentrations >60% when low partial pressures of O2

What happens RBCs in S Haemoglobinopathy

Crystallisation → Sickle shaped red cells

What is Sickle Cell Trait

Heterozygosity for HbS

What % of HbS is Sickle Cell Trait

45%

Significance of Sickle Cell Trait

It is of genetic, but rarely of clinical significance