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Cerebrospinal Fluid Analysis (CSF) Chloride 1323

Cerebrospinal Fluid Analysis (CSF)
VetBooks.ir Definition Causes of Abnormally High Levels

expected.
Cerebrospinal fluid (CSF) is the aqueous fluid • Increased protein: hemorrhage, increased glucocorticoids, accurate CSF cell counts are
that surrounds the brain and spinal cord. permeability of the blood-CSF barrier, or
Pleocytosis refers to an increased cellularity of localized production of immunoglobulins Specimen Collection and Handling
the CSF sample. Xanthochromia refers to yellow • Increased protein with normal cellularity: CSF in EDTA (lavender top tube) or red top
discoloration of the sample, typically from blood trauma, degenerative disease, intervertebral tube; refrigerate. Analysis should be performed
that has been present in the CSF for days or disc disease, fibrocartilaginous embolism, as soon as possible; cells deteriorate and lyse
longer. Albuminocytologic dissociation refers to cervical spondylomyelopathy, neoplasia, rapidly because of the low protein concentra-
a disproportionate elevation of CSF protein and viral infections tion. Addition of autologous serum to CSF (1:1)
compared to minimally elevated or normal • Increased protein and cell counts: inflam- helps preserve cells for cytologic evaluation.
CSF cell count. mation, infection (viral, fungal, protozoal, However, a separate aliquot of CSF must be
bacterial, rickettsial, parasitic), granuloma- submitted for protein determination and cell
Physiology tous meningoencephalitis, steroid-responsive counts. Any specimens with additives should
CSF provides support and protection for neural meningitis, neoplasia, immune-mediated be labeled with additive type and quantity.
structures, serves as a transport medium for disease, vasculitis, and necrotizing menin-
metabolic products to and from the brain, goencephalitis. Neoplastic cells are rare in Relative Cost: $$$; CSF protein only: $$
and provides a barrier to control the micro- CSF; lymphoma is the most commonly
environment of the nervous system. It is identified neoplasm. Pearls
normally colorless, clear, and almost acellular. • Many patients with neurologic disease
Cytocentrifugation is required for cytologic Next Diagnostic Steps to Consider may have no cytologic abnormalities in
evaluation of cells to assess for inflammation, if Levels are High CSF samples. Examples include idiopathic
hemorrhage, and infectious agents. Protein Correlate CSF findings with history, general epilepsy, hydrocephalus, intoxication or
(primarily albumin) concentration is normally physical, neurologic, and imaging findings. metabolic disease, vertebral disease, trauma,
very low and requires microprotein assays for Consider infectious disease titers (e.g., canine myelomalacia, and neoplasia.
accurate assessment. When CSF is submitted distemper virus, Neospora) on blood and/or • Blood contamination from sample collection
for analysis, aliquots are often also submitted CSF. can cause increase in protein and cells in
for infectious disease testing. CSF; as a general rule, hemorrhage may
Drug Effects account for 1 WBC for every 500 RBC in
Reference Interval Glucocorticoids may reduce inflammatory CSF.
• Dogs: red blood cell (RBC), < 30/mL; white cell counts, but may be required for patient
blood cell (WBC), 0-4/mL; protein, < 35 stabilization if a high degree of suspicion AUTHOR: Ruanna E. Gossett, DVM, PhD, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
mg/dL exists for steroid-responsive disease. Provided
• Cats: RBC, < 30/mL; WBC, 0-4/mL; CSF tap occurs < 24 hours after initiation of
Laboratory Tests
protein, < 36 mg/dL

Chloride

−
Definition Reference Interval • Calculate serum [Cl ] corrected to deter-
Major extracellular fluid (ECF) anion. Serum Dogs: 105-115 mEq/L. Cats: 114-123 mEq/L mine if proportional change relative to
+
−
−
−
[Cl ] essentially equals ECF [Cl ]. Cl concen- Unit conversion: 1 mEq/L = 1 mmol/L [Na ]:
+ −
trations influenced by Na , HCO 3 Corrected Cl = +
−
Causes of Abnormally High Levels (mean normalNa measured
+
)
Synonyms • With proportional [Na ] increase: same as Na × Measured Cl −
+
−
Cl, Cl − hypernatremia (see pp. 1234 and 1382). Reference interval for [Cl ] corrected is the same
−
+
• Without proportional increase in [Na ]: as for [Cl ].
Physiology hyperchloremic metabolic acidosis
−
Major component of gastric secretions; intes- ○ Primary: caused by loss of HCO 3 via Causes of Abnormally Low Levels
+
+
tinal resorption is coupled to Na resorption, gastrointestinal (e.g., diarrhea) or kidneys • With proportional decrease in serum [Na ]:
−
HCO 3 secretion. Kidneys play major regulatory (e.g., renal failure, renal tubular acidosis) same as hyponatremia (see p. 1382).
+
role: filtered by glomeruli, reabsorbed in renal ○ Compensatory: renal retention second- • Without proportional decrease in [Na ]:
+
tubules following Na and water. Acid-base ary to primary respiratory alkalosis ○ Primary hypochloremic metabolic alka-
status affects serum levels: there is an inverse (chronic) losis: gastrointestinal loss/sequestration
−
−
relationship between serum [Cl ] and [HCO 3 ]. (gastric vomiting, upper GI obstruction)
+
−
Serum [Na ] and [Cl ] usually change propor- Next Diagnostic Steps to Consider ○ Compensatory hypochloremic metabolic
−
tionally, but a selective increase in [Cl ] causes if Levels are High alkalosis: renal loss secondary to chronic
+
hyperchloremic acidosis; a selective decrease • Evaluate in relation to serum [Na ], acid-base respiratory acidosis
causes hypochloremic alkalosis. balance. ○ Other: hyperadrenocorticism
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