• Leucopenia: Low total white cell count (<4)
• Neutropenia: Low neutrophil count (<1.8, severe <1.0)
• Thrombocytopenia: Low platelet count (<140, severe <50)

Symptoms and Signs

• Fever
• may present with sepsis. See Neutropenic sepsis guideline
• Rash
• purpuric due to severe thrombocytopenia
• other due to underlying cause
• Bleeding/bruising due to low platelets
• Fatigue, malaise, dyspnoea
• may be due to co-existing anaemia
• May be asymptomatic

Causes

• Certain ethnic groups have lower normal range of neutrophils
• Afro-Caribbean
• Yemenites
• Arab Jordanians

Common

• Viral illnesses:
• EBV, CMV, parvovirus
• Severe bacterial infection, sepsis
• Liver disease with portal hypertension
• Ethanol excess
• Drugs
• prescribed, over the counter (OTC) and illegal
• Autoimmune

Less common

• HIV infection
• Disseminated intravascular coagulopathy (DIC)
• Imported infections
• malaria
• dengue fever
• leishmania
• Acute leukaemia
• Aplastic anaemia
• Other haematological malignancies/bone marrow infiltration
• Haemolytic uraemic syndrome (HUS)
• Thrombotic thrombocytopenic purpura
• Idiopathic thrombocytopenic purpura (ITP)
• Haemophagocytic syndrome (HLH), may co-exist with viral infections
• Adult Still's disease
• Autoimmune diseases
• SLE, rheumatoid arthritis, Felty's syndrome

Additional history required

• Full medication history
• including OTC and illicit drugs
• Full travel history
• may be necessary to go back several years
• Contact with infections
• Sexual history

• Repeat FBC, reticulocyte count and blood film
• U&E, LFT, CRP, LDH
• Vitamin B₁₂, folate, ferritin, transferrin saturation
• Coagulation screen including fibrinogen
• Blood cultures, irrespective of temperature. See Blood culture guideline
• If indicated by symptoms, sputum and urine culture
• If appropriate travel history, malaria film. See Fever in a returning traveller guideline
• If symptoms suggestive of respiratory infection, CXR
• Serology for EBV, CMV, parvovirus, HIV

• Give supportive treatment
• If clinical evidence of sepsis, treat as neutropenic sepsis
• see Neutropenic sepsis guideline
• discuss with haematologist, patient may require GCSF support
• If patient bleeding and significant thrombocytopenia, discuss platelet transfusion with haematologist

Cause is not apparent

• Repeat FBC regularly
• Repeat coagulation screen including D-dimers and fibrinogen
• Screen for further infective causes. Discuss with ID/microbiology
• If appropriate travel history, repeat malaria film
• CT thorax, abdomen and pelvis
• looking for significant lymphadenopathy, splenomegaly or collections
• Bone marrow aspiration and trephine. Discuss with haematologist
• Contact haematologist if:
• patient's blood counts are deteriorating significantly
• patient is clinically unstable or
• cause is not apparent

Further treatment

• Dependent on underlying cause
• If no cause apparent, give supportive treatment. Discuss with haematology

• Discharge patient if:
• cause apparent
• appropriate treatment instigated (if necessary)
• patient's parameters are improving without complications
• Arrange for blood parameters to be followed up until they are normal