#7536 - The Haemolytic Anaemias - Medical Finals & OSCEs Notes

The Haemolytic Anaemias

Presenting Complaint

Symptoms & Signs

Anaemia: tiredness, unwellness, pale conjunctiva, tachycardia, tachypnoea, hypotension; asymptomatic. Sudden onset: angina, weakness, shortness of breath.

Bilirubin stones developgallstone symptoms

Haemoglobinuria causes dark urine, seen in intravascular haemolysis

Exogenous factors: penicillin, L-DOPA, fava beans and henna in G6PD deficiency

Splenomegaly

Signs and symptoms of underlying disease: sickle cell anaemia, CLL, SLE etc.

They may be unwell if this is precipitated by infection

Bilirubinaemiajaundice, scleral icterus

Bleeding and petechiae if there is TTP causing MAHA

Investigations

Low RBCs high LDH in blood and High unconjugated bilirubin

MCV is normal or high (due to reticulocytes)

Platelets will be down in MAHA (due to DIC, TTP, HUS, prosthetic valves), maybe SLE and CLL.

Coombs’ test: the direct Coombs’ test shows that a haemolytic anaemia is autoimmune. It is positive when there are anti-RBC antibodies; antihuman globulins attack them and cause clumping, so here there is agglutination visibly seen. It is also known as the direct antiglobulin test or DAT.

Warm IgG antibodies react at 37degreesC whereas the IgM cold antibodies react at 20degreesC or below.

Blood film: may show spherocytes in hereditary spherocytosis; may show schistocytes (RBC fragments) in all causes of MAHA; shows sickle cells; excludes malaria as well; echinocytes in pyruvate kinase deficiency; shows reticulocytes if this is chronic and there is a compensatory reticulocytosis.

Genetic causes: enzyme assays and osmotic testing for fragile RBCs

Haemoglobin electrophoresis: screen for HbS in sickle cell anaemia and HbF and HbA2 in thalassaemia.

Cold agglutinins: In paroxysmal cold haemoglobinuria, there may be anti-P cold agglutinins. In other causes of cold autoimmune haemolysis, there may be anti-I antibodies e.g. with Mycoplasma pneumoniae and EBV.

There will be HbB in blood if this is intravascular

There will be urobilinogen in urine. This is formed from bilirubin breakdown in the gut and indicates bilirubin overload.

Abdo USS to estimate spleen size as examination is not reliable

CXR and ECG to estimate cardiopulmonary status

Causes

Acquired

Autoimmune: AIHA (autoimmune haemolytic anaemia)

• Warm

  • Idiopathic: has an unknown aetiology but has anti-RBC antibodies.

  • SLE

  • RA

  • Chronic lymphocytic leukaemia

  • Lymphoma

• Cold (‘cold agglutinin disease’)

  • Lymphoma again

  • Idiopathic again

  • EBV, HIV

  • Paroxysmal cold haemoglobinuria

  • Mycoplasma pneumonia

• drugs: penicillin, cephalosporins, sulfonylureas, sulphonamides, L-DOPA.

Isoimmune:

• Transfusion reactions

• Haemolytic disease of the newborn (HDN)

Non-immune:

• Infection: malaria, septicaemia

• Hypersplenism e.g. portal hypertension, infection, etc.

• Paroxysmal nocturnal haemoglobinuria

• Trauma:

  • March haematuria/footstrike haemolysis (repeated shocks to foot in soldiers or runners)

  • Microangiopathic haemolytic anaemia (MAHA), see below

Congenital

Hereditary haemolytic anaemias:

• Red cell membrane defects

  • Hereditary spherocytosis.

  • Elliptocytosis

• Enzyme deficiencies

  • G6PD deficiency.

  • Pyruvate kinase deficiency.

• Haemoglobin abnormalities

  • Thalassaemia

  • Sickle cell...