# Autoimmune Haemolytic Anaemia in Children

> Autoimmune haemolytic anaemia in children for NEET-PG Paediatrics, covering warm and cold antibodies, the direct Coombs test and Evans syndrome.

- Canonical URL: https://prepelephant.com/topics/neet-pg/paediatrics/autoimmune-haemolytic-anaemia-in-children
- Exam / course: NEET-PG · Subject: Paediatrics
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-14
- Last updated: 2026-10-14
- Reference basis: Nelson Textbook of Pediatrics; Nathan and Oski's Hematology and Oncology of Infancy and Childhood
- How to cite: "Autoimmune Haemolytic Anaemia in Children", PrepElephant, https://prepelephant.com/topics/neet-pg/paediatrics/autoimmune-haemolytic-anaemia-in-children

## Direct answer

Autoimmune haemolytic anaemia in children is an acquired anaemia in which autoantibodies coat red cells, confirmed by a positive direct antiglobulin test. Warm IgG disease, usually idiopathic in children, causes extravascular haemolysis and responds to corticosteroids. Cold agglutinin IgM disease, often post-infectious, causes complement-mediated haemolysis and needs avoidance of cold, while coexisting immune thrombocytopenia defines Evans syndrome.

## What you must remember

- **Warm antibody:** IgG autoantibodies react best at body temperature and cause mainly extravascular haemolysis in the spleen.
- **Cold antibody:** IgM agglutinins are active below about 30 degrees Celsius and cause complement-mediated haemolysis (largely hepatic, with some intravascular component), often with acrocyanosis of the extremities.
- **Direct Coombs test:** positive in autoimmune haemolysis, showing IgG with or without C3 in warm disease and C3 alone in cold disease.
- **Film and labs:** spherocytes, reticulocytosis, raised lactate dehydrogenase and indirect bilirubin, and low haptoglobin support the diagnosis.
- **Associations:** most warm disease is idiopathic in children, but systemic lupus erythematosus, immunodeficiency such as common variable immunodeficiency, lymphoproliferative disease and infections like EBV or Mycoplasma are recognised triggers.
- **Paroxysmal cold haemoglobinuria:** a biphasic IgG (Donath-Landsteiner) antibody, historically linked to viral illness, causes haemoglobinuria after cold exposure.
- **Evans syndrome:** autoimmune haemolysis with immune thrombocytopenia, sometimes with neutropenia, warrants evaluation for autoimmune lymphoproliferative syndrome.
- **First-line therapy:** prednisolone at around 1 to 2 mg/kg per day for warm disease, tapered over weeks, with rituximab, azathioprine or splenectomy (after vaccination) reserved for relapse.

## Warm or cold: a comparison in one table

A 6-year-old presents with pallor, jaundice and reticulocytosis after a viral illness, and the direct Coombs test becomes the key investigation. The thermal range and the Coombs pattern decide the class, so both are checked first.

| Feature | Warm antibody (IgG) | Cold agglutinin (IgM) |
|---|---|---|
| Thermal range | Around body temperature, reacting best at 37 °C | Below about 30 °C, reacting in the cold |
| Site of haemolysis | Extravascular, in the spleen | Complement-mediated, largely hepatic, partly intravascular |
| Direct Coombs pattern | IgG with or without C3 | C3 alone |
| Steroid response | Usually good, with a taper over weeks | Usually poor, so do not rely on steroids |
| Common triggers | Idiopathic, lupus, lymphoma or immunodeficiency | Mycoplasma, EBV or other viral infection |
| Course | Relapsing, often needs long therapy | Usually self-limiting in children |
| Management focus | Steroids, then second-line agents | Keep warm, treat trigger, rituximab if severe |

Warm disease responds to steroids, whereas acute cold disease is often self-limiting after infection and needs warmth and avoidance of cold. A positive test with complement alone and acrocyanosis points to cold disease.

## Where the exam tries to catch you

Autoimmune haemolysis questions usually test whether you can match the antibody to the thermal range and the Coombs pattern.

- **Trap:** using steroids as the main therapy for cold agglutinin disease. — **Correct:** cold disease responds poorly to steroids, so warmth, trigger treatment and rituximab in severe cases are preferred.
- **Trap:** reading a negative direct Coombs test as excluding autoimmune haemolysis. — **Correct:** the test can be negative in some patients, so repeat testing and the indirect Coombs test help.
- **Trap:** treating only the anaemia when haemolysis and thrombocytopenia coexist. — **Correct:** this combination is Evans syndrome and needs evaluation for autoimmune lymphoproliferative syndrome.

## Frequently asked questions

### Which antibody class causes warm autoimmune haemolytic anaemia?
Warm autoimmune haemolytic anaemia is caused by IgG autoantibodies that bind red cells best at body temperature. The direct antiglobulin test typically shows IgG, with or without complement.

### Why does cold agglutinin disease cause haemoglobinuria while warm disease usually does not?
Cold agglutinin disease is mediated by IgM antibodies that fix complement, so part of the haemolysis occurs within the vessels and can release free haemoglobin, with haemoglobinuria after cold exposure. Warm IgG disease mainly causes extravascular haemolysis in the spleen, so haemoglobinuria is less typical.

### What is Evans syndrome in children?
Evans syndrome is the coexistence of autoimmune haemolytic anaemia and immune thrombocytopenia, sometimes with neutropenia. It warrants evaluation for autoimmune lymphoproliferative syndrome and immunodeficiency, because these disorders can underlie it.

### What is the first-line treatment for warm autoimmune haemolytic anaemia in children?
Corticosteroids, typically prednisolone at around 1 to 2 mg/kg per day, are the first-line treatment for warm autoimmune haemolytic anaemia. Children who relapse or fail steroids may receive rituximab, azathioprine or splenectomy after vaccination.