HNY Policy and Pathway Repository - North Yorkshire

A low white cell count (WCC) is most commonly seen as a transient feature following viral infection. Where there has been no recent history of infection, or where the low WCC is persistent, then other causes should be considered.

None provided

Differential Diagnosis

Neutropenia:

• Constitutional - Ethnic variation in Black Africans and some Arab or Mediterranean patients includes a neutrophil count down to 0.8 x10⁹ /L.
• Congenital uncommon but consider in young patients if no previous normal blood counts. Variable inheritance and severity.
• Post-viral- may persist for several weeks and be followed by a prolonged autoimmune neutropenia lasting for several months.
• Drug-induced- long list of possibilities: especially chemotherapy; phenothiazines and other anti-psychotics; anti-epileptics; anti-arrhythmics, anti-thyroid drugs; antibiotics; ACE-inhibitors; sulphasalazine and NSAIDs.
• Autoimmune- may be seen alone or with other autoimmune disease.
• Vitamin B12 / folate deficiency
• Bone marrow failure- may give isolated neutropenia but more commonly associated with anaemia and / or thrombocytopenia.
• Unusual causes such as Felty's syndrome.

Lymphopenia, is non-specific and has many possible causes including:

• Infection- acute or chronic infection, especially HIV or TB
• Autoimmune disease / connective tissue disease
• Steroid therapy
• Cardiac failure
• Malignancy

Examination:

Should include baseline observations. Examine for hepato-splenomegaly and for lymphadenopathy. Local signs of infection

Baseline investigations:

Blood film should be examined. Consider autoimmune screen or viral serology (including HIV) as appropriate.

Management:

• Consider switching non-essential medications if suspicion of drug-induced neutropenia. Neutrophil count should begin to recover within a few days / weeks depending on the medication. If neutrophils >1.0 x10⁹/L with no increase in infections then do not change important medications.
• If neutrophil count <1.0x10⁹/L then patients should report any fever or symptoms of infection immediately and may need hospitalisation for intravenous broad spectrum antibiotics.

Referral:

• Consider Haematology referral if:
  • Unexplained neutropenia <1.0x10⁹ /L.
  • Unexplained neutropenia <1.5 x10⁹ /L if persistent or with other cytopenias.
• We do not routinely investigate isolated lymphopenia.

Haematology Handbook - South Tees Hospitals NHS Foundation Trust

• South Tees Hospitals