Protein, Total, Spinal Fluid
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Cerebrospinal fluid (CSF) proteins are those that remain in CSF following the ultrafiltration of plasma through the choroidal capillary wall. Some proteins that are unique to CSF are synthesized in the central nervous system. In general, diseases that interrupt the integrity of the capillary endothelial barrier lead to an increase in the total CSF protein.
CSF protein is generally increased in all types of meningitis, cerebral infarction, brain abscess, meningovascular syphilis, subarachnoid hemorrhage, some brain tumors, trauma to the brain, some cases of multiple sclerosis, encephalomyelitis, and degenerative neurologic diseases. A decreased CSF protein may occur in water intoxication, CSF leak (CSF rhinorrhea or otorrhea), and hyperthyroidism.
Detecting disruptions of the blood-brain barrier or intrathecal synthesis of immunoglobulins
Striking elevations of cerebrospinal fluid (CSF) total protein are noted in bacterial meningitis; smaller elevations occur in the other inflammatory diseases and with tumor or hemorrhage. The effect of any of these conditions is that the proportions of specific proteins in CSF increasingly resemble serum.
In order to assess increased permeability or increased intrathecal production of proteins, simultaneous serum specimen and CSF specimens should be taken.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Increased cerebrospinal fluid (CSF) total protein is sensitive, but not specific, for detecting disruptions of the blood-brain barrier or intrathecal synthesis of immunoglobulins.
The presence of hemoglobin in CSF will cause an increase in measured total protein by this method. Internal validation studies have been conducted to estimate the contribution of hemolysis to the measured total protein concentration, and are appended to the result as a comment in these situations. Results should be interpreted with caution as hemolysis may be present due to traumatic lumbar puncture or due to a CNS hemorrhagic process.
Specimens should be collected prior to the intrathecal administration of contrast media. Significant positive bias can occur when CSF contains contrast media. Examples of contrast media include Iopamidol, Iohexol, and Metrizamide.
Blood in the CSF specimen invalidates the protein value.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
> or =12 months: 0-35 mg/dL
Reference values have not been established for patients that are <12 months of age.
Clinical References Provides recommendations for further in-depth reading of a clinical nature
1. Tietz Textbook of Clinical Chemistry. Fourth edition. Edited by CA Burtis, ER Ashwood, DE Bruns. Philadelphia, WB Saunders Company, 2006
2. Killingsworth LM: Clinical applications of protein determinations in biological fluids other than blood. Clin Chem 1982;28:1093-1103
3. Henry’s Clinical Diagnosis and Management by Laboratory Methods. Cerebrospinal, synovial, and serous body fluids. Edited by McPherson and Pincus. Philadelphia, WB Saunders Co, 2007, 431-435