At 2001-07-19 09:52 +0100, M A Al-Jubouri wrote:
> Patients with suspected bacterial meningitis are
>emprically treated with antibiotics on clinical
>grounds without waiting for biochemical and
>microbiological investigation of CSF. Does CSF lactate
>add extra information to diagnosis of this condtition
>using usual biochemical (glucose and protein)and
>microbiological investigation in straightforward
>cases?
The advantages with CSF Lactate are:
1. It has a sufficiently high predictive values both for positive
and negative test to be considered to set the definitive diagnosis
in one single test. In practice, however most clinicians would not
dare to omit treatment with antibiotics also in cases where CSF Lactate is
<=2.4 mmol/L, although the risk of false negative test is very low.
2. The test can be done very rapidly using automatic analyzers and manual
techniques. It is well suited for the emergency laboratory. A definitive
answer is obtained within minutes, which is considerably faster than any
culture test.
3. Most CSF methods need comparison with the same analyte in blood. This is
not necessary for CSF Lactate but for the more frequently used CSF/Blood
glucose test. Furthermore the latter test has considerably lower predictive
values both for positive and negative test.
The main objection against CSF Lactate (and all other CSF methods) in
meningitis is the risk of herniation due to increased intracranial
pressure. This can be avoided by using an appropriate sampling technique.
A CT or MRI scan can also show if the patient has an increased intracranial
pressure, although such a scan is expensive and may waste time in an
emergency situation.
>Is there evidence that it picks up certain cases that
>are not otherwise picked up by existing means?
It is a matter of time - Culturing sets the definitive diagnosis but it
cannot be done after treatment of the patient with antibiotics.
In an emergency situation CSF Lactate is the only biochemical test that
should be used. Drop the CSF/blood Glucose test! Besides CSF Lactate it
does not contribute to the diagnosis, neither to the presence of bacterial
meningitis nor the absence.
Mr Sten Öhman, PhD
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