Neutropaenia

Neutropaenia is an absolute neutrophil count (ANC) of <1.5 x 10⁹/L. There is an increased risk of severe sepsis if the neutrophil count is <0.5 x 10⁹/L.

Severity of Neutropaenia

 

• Mild                              0 – 1.5 x 10⁹/L             No further investigation necessary
• Moderate                      50 – 0.99 x 10⁹/L          Neonatal investigation required
• Severe                         20 – 0.49 x 10⁹/L           Refer for immediate Haematology advice              
• Very severe                   <0.2 x 10⁹/L                 Refer for immediate Haematology advice              

Causes

• Sepsis
• Physiological
• Neonatal alloimmune neutropaenia
• Autoimmune neutropaenia
• Lineage steal in prematurity or growth restriction
• Inherited
  • Congenital neutropaenia
  • Bone marrow failure syndromes
  • Cyclical neutropaenia
• Metabolic diseases
• Vitamin B12 and folate deficiency
• Drug-induced neutropaenia

 

Congenital neutropaenia (the most serious cause):

It is most important to try to identify neonates with congenital neutropaenia as they are at the highest risk of infection. This is an extremely rare condition. Factors that make congenital neutropaenia more likely include:

• History of significant infections
• Other cytopenias (corrected for age)
• Clinical findings suggestive of a multisystem disorder e.g., failure to thrive, bone abnormalities
• Family history (although most are autosomal recessive)
• Consanguinity

If congenital neutropaenia is suspected from the history, please discuss with haematology.

 

Commonest causes of neutropaenia

Physiological and immune neutropaenia are the commonest causes of neutropaenia in well neonates and most do not have significant problems with infection. However, this diagnosis is usually confirmed only after resolution of the neutropaenia and so advice must be given to parents to present to the RHCYP emergency department if baby becomes unwell, as discussed below.

• Physiological neutropaenia

Many babies are found to be slightly neutropenic if they have a FBC done as part of the work up for other neonatal problems. The normal range from birth to 2 months changes rapidly and is much lower than an older baby or child. If in doubt, please discuss with haematology to avoid unnecessary testing.

• Neonatal alloimmune neutropaenia

Most cases resolve by ~12 weeks after birth and rates of serious infection are low.

• Autoimmune neutropaenia

Almost all cases of autoimmune neutropaenia resolve spontaneously by the age of 5 years and many children have no particular problems with infection. It would be unusual for this to present in the neonatal period.

Neutropaenia in preterm infants

New-onset neutropaenia (especially in association with overall leucopenia) in preterm infants would be suggestive of a possible infection. It should be investigated as clinically indicated as these infants are at higher risk for infection. Neutropaenia due to lineage steal can be seen in preterm infants who are growth-restricted and usually resolves spontaneously.

Persistent neutropaenia can sometimes be seen in ‘well’, growing, preterm infants. The infants should still be assessed for clinical signs of infection. If truly well, then the guideline for management of neutropaenia in ‘well’ term infants below can be followed.

Neutropaenia in term infants 

If unwell admit to the unit, perform a septic screen and start antibiotics after discussion with a consultant.

If baby appears well (no evidence of infection, cord infection/detachment problems, failure to thrive, neurological abnormality) and the other components of the full blood count are within normal limits, then if:

ANC 1.0 – 1.5 x 10⁹/L:

• No further follow-up is required.

ANC 0.50 – 0.99 x 10⁹/L:

• Ensure that the blood film has been reviewed by a haematologist.
• Allow home with advice to parents regarding signs of infection and if any emerge, then baby should be seen urgently at RHCYP emergency department (children with suspected infection cannot return to the neonatal unit).
• Advise that immunisations can be given routinely if lymphocyte count is normal.
• Repeat FBC in 1 week. (There is not likely to be a significant improvement in ANC in this time, but it is important to check that the other cell lines remain within normal limits and that baby is well).
  • If there are new FBC abnormalities or clinical concerns at this 1-week time point, discuss with haematology – Bleep 9290
  • If there are no new clinical concerns or FBC problems, plan a final FBC in 4 further weeks
    • If ANC recovers ≥ 1.0 x 10⁹/L, then no further follow-up is required
    • If ANC persists < 1.0 x 10⁹/L, refer to Haematology for follow-up

 

 

ANC <0.50 x 10⁹/L

• Discuss all cases with haematology – Bleep 9290
• If baby is well and there are no other clinical concerns, then enhanced surveillance as above may be recommended
• If clinical or other concerns, then direct haematology review may be arranged