Paediatrics chapters
Immune thrombocytopenic purpura in children
The commonest cause of sudden bruising in a well child: antibody-mediated platelet destruction after a viral illness, how to diagnose it and exclude leukaemia, when to watch and when to treat with steroids, IVIG or anti-D, and why most children recover within months.
- ITP is isolated thrombocytopenia caused by IgG (or IgM) antibodies that coat platelets, which the spleen destroys; in children it usually follows a viral infection by 1-4 weeks, peaks at 2-5 years, and affects boys and girls equally.
- A well child with sudden petechiae, bruising and nosebleeds, no lymph nodes, liver or spleen, a low platelet count (often under 20,000) and normal Hb, white cells and film; marrow (normal or increased megakaryocytes) is needed only if features are atypical, to exclude leukaemia or aplastic anaemia.
- Most need observation only; treat significant bleeding with very low platelets using IVIG, a short course of steroids or anti-D; about 80% recover within 6 months; chronic ITP (beyond 6-12 months) is commoner in adolescent girls and may need splenectomy.
On this page
Overview
Immune (idiopathic) thrombocytopenic purpura (ITP) is an acquired bleeding disorder in an otherwise healthy child, marked by:
- Thrombocytopenia (platelets below 150,000/mm³, usually far lower),
- A purpuric rash and other skin or mucosal bleeding,
- A normal bone marrow, and
- No other cause for the low platelets.
Acute ITP is the commonest bleeding disorder of childhood and usually settles on its own. The main clinical task is to be sure it is not leukaemia or marrow failure, and to avoid over-treating a condition that rarely causes serious harm.
Classification
| Type | Definition used here | Typical patient |
|---|---|---|
| Acute | Recovers within about 6 months | Young child (2-5 years), boys and girls equally, after a viral illness, abrupt onset |
| Persistent | Lasting beyond the acute phase but not yet chronic | Some recover late |
| Chronic | Thrombocytopenia lasting beyond 6-12 months (Nelson) or more than 1 year (Akbar) | Adolescents, girls more often, insidious onset; look for autoimmune disease |
The two books used here define only acute and chronic ITP, and they differ on the chronic cut-off (6-12 months in Nelson; 1 year in Akbar). The term "persistent" is used for the period in between.
Epidemiology and triggers
- Symptomatic ITP occurs in roughly 3-8 per 100,000 children per year (Akbar).
- Acute ITP is commonest under 10 years, with a peak at 2-5 years.
- It often follows a viral infection (upper respiratory infection, rubella, varicella, measles, Epstein-Barr virus) by about 1-4 weeks.
Pathophysiology
- The child makes IgG (or IgM) autoantibodies against glycoproteins on the platelet membrane, often after a viral infection.
- Antibody-coated platelets are caught by Fc receptors on macrophages, mainly in the spleen, and destroyed early.
- The marrow responds with normal or increased megakaryocytes, which may be larger than usual.
- Platelet production may also be relatively low: thrombopoietin levels are not raised as expected, especially in chronic ITP.
- Surviving platelets are young and large, and work well, which is one reason serious bleeding is uncommon even at very low counts.
Clinical features
- An otherwise well, active child who suddenly develops petechiae, purpura, multiple bruises (often on the legs and in places not exposed to injury).
- Mucosal bleeding in about a third: epistaxis and gum bleeding.
- Less often: gastrointestinal bleeding, haematuria, vaginal bleeding, retinal or conjunctival haemorrhage.
- Intracranial haemorrhage is the feared complication but occurs in fewer than 1%.
- Examination is otherwise normal: no lymphadenopathy, hepatomegaly or splenomegaly, no pallor beyond what bleeding explains, no bone pain.
Lymph nodes, a big liver or spleen, bone pain, pallor or fever in a child with low platelets suggest leukaemia or another disease, not ITP.
Laboratory investigations
| Test | Finding in ITP |
|---|---|
| Platelet count | Low, usually under 50,000/mm³ and often under 20,000 (or even under 10,000) |
| Haemoglobin | Normal (mild anaemia in about 15%, only from bleeding) |
| White cell count and differential | Normal |
| Blood film | Large platelets; no blasts; normal red and white cells |
| PT and APTT | Normal (not needed if the blood count and film are typical) |
| Bleeding time | Prolonged (not routinely needed) |
| Bone marrow | Normal or increased megakaryocytes; normal red and white cell series |
| Platelet-associated IgG/IgM | May be present (not routine) |
In ITP the only abnormal finding on the blood count is the low platelet count; anaemia, if present, is explained by bleeding.
When is a bone marrow examination needed?
ITP is mainly a clinical diagnosis, and the marrow is not routinely examined. It is indicated when features are atypical:
- Abnormal haemoglobin (not explained by bleeding), white count or film.
- Organomegaly, lymphadenopathy, bone pain or systemic illness.
- Failure to recover, or before giving steroids if leukaemia has not been reasonably excluded.
In chronic ITP
Look for an underlying cause: SLE and other autoimmune disease, HIV, and drugs.
Differential diagnosis of thrombocytopenia
| Group | Conditions and clues |
|---|---|
| Marrow infiltration or failure | Leukaemia (pallor, bone pain, nodes, spleen, blasts), aplastic anaemia (pancytopenia, low reticulocytes), lymphoma |
| Consumption | DIC and sepsis (sick child, prolonged PT and APTT, low fibrinogen), haemolytic uraemic syndrome and TTP (fragmented red cells, renal failure), giant haemangioma (Kasabach-Merritt) |
| Sequestration | Hypersplenism |
| Other immune | SLE, HIV, drug-induced (anticonvulsants, antibiotics, heparin, quinidine) |
| Congenital | Wiskott-Aldrich syndrome (boys, eczema, infections, small platelets), TAR syndrome (absent radii, thumbs present), Fanconi anaemia, Bernard-Soulier (giant platelets) |
| Newborn | Neonatal alloimmune thrombocytopenia, maternal ITP, congenital infection |
| Bleeding with normal platelets | von Willebrand disease, platelet function defects, vasculitic purpura, non-accidental injury |
In ITP the child is "well, apart from the spots"; in leukaemia the child is unwell, pale and has organs to feel.
Management
General measures (all children)
- Explain the benign natural history and reassure the family.
- Avoid contact sports, rough play and injury while platelets are very low.
- Avoid aspirin, NSAIDs and other drugs that affect platelets; avoid intramuscular injections.
- Advise the family on warning signs: heavy or persistent bleeding, headache, vomiting, drowsiness.
Observation or drug treatment?
- Many children need no drug treatment. Therapy is seldom needed when platelets are above 30,000/mm³ and the child is not bleeding significantly (Nelson).
- Drugs raise the platelet count faster but do not change the long-term outcome, and there is no proof that early treatment prevents intracranial bleeding.
- Treatment is considered for significant (moderate or severe) bleeding with very low platelets (for example under 10,000/mm³), or high-risk situations.
| Option | Key points |
|---|---|
| Intravenous immunoglobulin (IVIG) | About 0.8-1 g/kg daily for 1-2 days; blocks splenic Fc receptors; platelets usually rise within 24-72 hours; expensive |
| Corticosteroids (prednisolone) | High dose for a short course (about 2 weeks), then tapered and stopped; cheaper; avoid prolonged use (growth failure, diabetes, osteoporosis) |
| Anti-D immunoglobulin | Only for Rh-positive children with a spleen; forms antibody-coated red cells that occupy splenic Fc receptors; cheaper than IVIG, slower; causes mild haemolysis |
| Platelet transfusion | Only for life-threatening bleeding (for example intracranial), usually with IVIG and steroids, because transfused platelets are destroyed quickly |
Platelet transfusion is not routine in ITP: the antibodies destroy transfused platelets within hours. It is kept for life-threatening haemorrhage.
Chronic ITP
- Aim is to prevent serious bleeding, not to normalise the count; treat only when platelets are dangerously low or the child bleeds.
- Repeated IVIG, anti-D or pulse steroids can tide children over.
- Splenectomy gives lasting remission in about 70-80% of chronic childhood ITP (Nelson; Akbar 60-90%), but:
- Consider only after at least 1 year of significant thrombocytopenia not controlled by medical treatment.
- Delay until 5 years of age if possible.
- Give pneumococcal, meningococcal and Hib vaccines beforehand and penicillin prophylaxis afterwards.
- Children who responded (even briefly) to steroids or IVIG tend to respond better to splenectomy.
- In acute ITP, splenectomy is reserved for life-threatening bleeding not controlled otherwise.
- Other agents for resistant cases include immunosuppressants and other drugs given by specialists.
Treatment raises the platelet count faster but does not alter the natural history of ITP.
Prognosis and follow-up
- About 80% of children recover within 6 months (Nelson; Akbar 70-80%), and about 90% eventually remit spontaneously.
- About 20% develop chronic ITP.
- Severe bleeding occurs in fewer than 3% and intracranial haemorrhage in fewer than 1%.
- Features that predict chronic ITP (Akbar):
- Female sex.
- Age over 10 years at presentation.
- Insidious onset of bruising.
- Presence of other autoantibodies.
- Follow-up: repeat platelet counts until recovery; review promptly for new bleeding; screen chronic cases for SLE and HIV.
ITP in the newborn
Babies born to mothers with ITP may have low platelets from transplacental antibodies; this resolves over the first month. Neonatal alloimmune thrombocytopenia is due to maternal antibodies against paternal platelet antigens on the baby's platelets and carries a risk of intracranial bleeding; treatment includes IVIG and washed maternal platelets.
Expect: a well 3-year-old with petechiae and bruising two weeks after a viral illness, normal haemoglobin and white count and a platelet count of 15,000 with no organomegaly; antibody-mediated splenic destruction; marrow showing normal or increased megakaryocytes and when the marrow is needed (atypical features, to exclude leukaemia or aplasia); observation for most; IVIG, short-course steroids and anti-D for bleeding; platelet transfusion only for life-threatening bleeding; about 80% recovering within 6 months; chronic ITP in adolescent girls; splenectomy indications and vaccines; and differentiating ITP from leukaemia, aplastic anaemia, Wiskott-Aldrich and TAR syndrome.
Quick revision
- Acute ITP: well child, 2-5 years, after viral illness, sudden petechiae and bruises.
- Antibody-coated platelets destroyed in the spleen; marrow megakaryocytes normal or increased.
- Isolated low platelets; Hb, WBC and film otherwise normal; large platelets.
- No nodes, liver or spleen: if present, think leukaemia.
- Marrow only if atypical.
- Treat bleeding, not numbers; rarely needed above 30,000.
- IVIG 0.8-1 g/kg for 1-2 days; short steroid course; anti-D if Rh positive.
- Platelet transfusion only for life-threatening bleeding.
- About 80% recover within 6 months; 20% chronic (girls, over 10, insidious onset).
- Splenectomy for chronic ITP after 1 year, after age 5, with vaccines and penicillin.
Written by The House Job from standard references (Basis of Paediatrics by Pervez Akbar; Nelson Essentials of Paediatrics).
FAQ
Does every child with ITP need a bone marrow test?
No. A well child with typical features and an isolated low platelet count can be diagnosed clinically; the marrow is examined when the blood count, film or examination is atypical, to exclude leukaemia or aplastic anaemia.
Should a child with a platelet count of 15,000 but only skin bruising be treated?
Many such children are safely observed, because treatment raises the count faster but does not change the outcome; drugs are used when there is significant bleeding or the risk is high.
Why are platelet transfusions not given routinely in ITP?
The same antibodies that destroy the child's own platelets destroy transfused ones within hours, so transfusion is kept for life-threatening bleeding.
Which children are likely to develop chronic ITP?
Girls, children over 10 years at presentation, those with a slow, insidious onset, and those with other autoantibodies.