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Reference ranges for other CSF constituents Substance Lower limit Upper limit Unit Corresponds to % of that in blood plasma; RBCs: n/a [2] 0 [2] / negative: cells/μL or cells/mm 3: WBCs: 0 [2] 3 [2] cells/μL cells/mm 3: pH: 7.28 [1] 7.32 [1] (-log M) PCO 2: 44 [1] 50 [1] mmHg 5.9 [7] 6.7 [7] kPa: PO 2: 40 [1] 44 [1] mmHg 5.3 [7] 5.9 [7] kPa
[34] [36] The presence of red blood cells and xanthochromia may indicate subarachnoid hemorrhage; whereas central nervous system infections such as meningitis, may be indicated by elevated white blood cell levels. [36] A CSF culture may yield the microorganism that has caused the infection, [34] or PCR may be used to identify a viral cause. [36]
Under normal conditions, there are usually less than 5 white blood cells per μL of CSF. In a pleocytic setting, the number of lymphocytes can jump to more than 1,000 cells per μL. Increases in lymphocyte count are often accompanied by an increase in cerebrospinal protein concentrations in addition to pleocytosis of other types of white blood ...
The majority of the CSF is formed in the choroid plexus and flows through the brain along a distinct pathway: moving through the cerebral ventricular system, into the subarachnoid space surrounding the brain, then draining into the systemic blood column via arachnoid granulations of the dural sinuses or to peripheral lymphatics along cranial ...
It may also be used to detect the presence of malignant cells in the CSF, as in carcinomatous meningitis or medulloblastoma. CSF containing less than 10 red blood cells (RBCs)/mm 3 constitutes a "negative" tap in the context of a workup for subarachnoid hemorrhage, for example. Taps that are "positive" have an RBC count of 100/mm 3 or more. [9]
Still, the blood values are approximately equal between the arterial and venous sides for most substances, with the exception of acid–base, blood gases and drugs (used in therapeutic drug monitoring (TDM) assays). [6] Arterial levels for drugs are generally higher than venous levels because of extraction while passing through tissues. [6]
The reason for this is not known. It has been suggested that the endothelial cells of the venous sinus create vacuoles of CSF, which move through the cell and out into the blood. [7] The importance of arachnoid granulations for the drainage of CSF is controversial. [8]
The CSF sample is examined for presence and types of white blood cells, red blood cells, protein content and glucose level. [8] Gram staining of the sample may demonstrate bacteria in bacterial meningitis, but absence of bacteria does not exclude bacterial meningitis as they are only seen in 60% of cases; this figure is reduced by a further 20% ...