Doctors' Newsletter - Autumn 2008 - Douglass Hanly Moir Pathology

Neutrophils: The Good, The Bad and the Ugly
Dr Debbie Clark
Haematologist
Neutrophilia
In the normal adult full blood count,
neutrophils form the majority
cell percentage of the white cell
differential count. Their main function
is to fight bacterial infection and the
majority of cases with neutrophilia will
be due to infection, an association
that doctors are universally familiar
with.
The absolute neutrophil count is
of greater significance than the
percentage. Reference range in a
normal adult is: 2.0 – 7.5 x 10^9 /L.
Commonly, a left shift is also
reported at the time of a neutrophilia.
This simply means that less mature
cells of the same series, such as
band forms or even myelocytes,
are also present in the film.
See diagram 1.
Although most neutrophilias
will be secondary to obvious
infection, sometimes there is no
clinical indication of this and then
the question arises: what is this
neutrophilia due to and should I be
worried about it At the back of
everyone’s mind is the possibility of
an early myeloid leukaemia. There
are, however, a substantial number of
other causes of a neutrophilia which
are more common than primary
marrow disorders. Table 1 lists them.
Physiological causes of a
neutrophilia are a result of circadian
rhythms and reaction to physiological
processes. The neutrophil count
rises after a meal and after physical
exertion.
Pregnancy is frequently associated
with a neutrophilia and our quoted
reference ranges on the full blood
count report reflect these changes, if
we have sufficient clinical information
to that effect. However, the ranges
are not so readily fixed as in the
non-pregnant state and should be
interpreted with a degree of flexibility.
Myelocytes are a common finding.
Many factors influence the neutrophil
count in pregnancy: the stage of
pregnancy and the presence of a
multiple pregnancy, for example.
Some drugs are often associated
with a neutrophilia: steroids are
a frequently observed cause of a
neutrophilia and myelocytes are often
seen in the film. Of course, patients
on steroids may have an increased
risk of infection, which complicates
the interpretation of this finding.
Other drugs include: lithium, and
GCSF.
Inflammation of tissue without
bacterial infection may also give rise
to a neutrophilia. Examples include
myocardial infarction, tissue necrosis,
trauma and vasculitis.
Acute haemorrhage or
haemolysis, neoplasia, as well as
some acute metabolic disorders
may all sometimes be associated
with a neutrophilia. Lastly, a
neutrophilia may be an early sign of
a myeloproliferative disorder. In
chronic myeloid leukaemia, it is
the predominant feature of the blood
count, with a white count often in the
200-300 x 10^9 /L range. In its very
early stages, there may be a milder
neutrophilia, but there is often quite
a marked left shift. The presence
of a basophilia or eosinophilia, plus
changes in other parameters, such
as the platelets, may give a clue to
the underlying disorder.
Other myeloproliferative disorders,
such as polycythaemia rubra
vera and myelofibrosis, may
also include a neutrophilia
among their features. Chronic
myelomonocytic leukaemia,
a disorder of the elderly which
includes both myeloproliferative and
myelodysplastic features, usually
shows a marked monocytosis with
an accompanying neutrophilia and
left shift.
Table 1: Causes of a neutrophilia
Bacterial infection
Tissue inflammation / necrosis
Drugs (e.g. steroids)
Pregnancy
Acute haemorrhage or haemolysis
Neoplasia
Severe metabolic disorders
Myeloproliferative disease
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