Haemolytic Anaemia (HA)

Exam Cram

• Haemolysis: destruction of red blood cells

• Haemolytic anaemia: anaemia caused by haemolysis

• Investigations: low Hb & haptoglobin, raised reticulocytes and LDH

• Management: as per underlying cause (genetic or acquired)

Outline

Background

• RBC lifespan is typically 120d (3 months)

• RBC Haemolysis describes the RBC destruction

Assessment

History

• Anaemia: fatigue, palpitations, chest pain, presyncope

Examination

• Conjunctival pallor

Investigations

• Low Hb with raised or normal MCV

• Raised reticulocytes and LDH

• Low haptoglobin

Diagnosis

Diagnostic criteria: haemolytic anaemia is by lab results above 

Classification: by cause

A. Intravascular

Occurs inside the blood vessels

1. 1. Immune

      • ABO/ rhesus incompatibility- transfusion mismatch

      • AutoImmune Haemolytic Anaemia (AIHA) 

        • Hot

          • Drugs- penicillin, erythromycin

          • Autoimmune- Systemic Lupus Erythematous , Antiphospholipid Syndrome (APS) , Rheumatoid Arthritis 

          • CLL (Chronic Lymphocytic Leukaemia) Lymphoma 

          • Idiopathic

        • Cold

          • Infective: Mycoplasma Pneumoniae , EBV 

          • CLL (Chronic Lymphocytic Leukaemia) Lymphoma 

          • Idiopathic

   2. Non Immune

      • Mechanical- heart valves, ECMO

      • Infection- sepsis, malaria, clostridium perfringes,

      • Hypotonic solution or drowning

      • Toxin- lead, mercury

      • Microangiopathic haemolytic anaemia (MAHA)

        • TTP (Thrombotic thrombocytopenic purpura) 

        • E.coli Haemolytic Uraemic Syndrome

        • HELLP Syndrome: pre-eclampsia 

      • Trauma

      • Wilson's disease

B. Extravascular

Occurs outside blood vessels, e.g. spleen

1. Intrinsic factors

1. 2. • Hereditary

        • G6PD Deficiency

        • Hereditary Spherocytosis 

        • Sickle Cell Disease

        • Thalassemia 

      • Acquired

        • PNH (paroxysmal nocturnal haemoglobinuria) 

2. Extrinsic factors

1. 2. • Hypersplenism

        • Liver Cirrhosis : portal hypertension

        • Myeloproliferative disorders

        • Infective causes

Management

Diagnostic work flow: 

1. Confirm haemolysis by lab results: Hb, MCV, haptoglobin, reticulocytes

2. Classify by cause

Resources and References

1. https://litfl.com/haemolytic-anaemia/

Written in 2025