Body Fluids Flashcards
CSF
Flows where?
Functions?
- Flows in subarachnoid space
- Functions to give physical support/protection, controlled chem environment to supply nutrients/remove wastes, and transport
Lumbar puncture area and tube order
- L3/L4
1. Chemistry/Serology
2. Microbiology
3. Hematology
4. Extra/cytology
Why investigate CSF?
- Infection
- Demyelinating disease
- Malignancy
- Hemorrhage into CNS
What color is xanthrochromic CSF and why is it that color?
Yellow due to bilirubin from RBC breakdown in old hemorrhage
T/F: CSF from fresh hemorrhage tends to clot
False
CSF from traumatic tap (decreasing amounts of redness in each successive tube) tends to clot
4 main markers in CSF
- Glucose
- Protein (total/specific)
- Lactate
- Glutamine
How to prep CSF specimen for analysis
Always centrifuge even if clear/colorless!
Glucose in CSF
CSF transport
When to collect
Conc in CSF
- Enters CSF through facilitative protein transport
- Collect blood glucose 2-4 hrs prior
- CSF glucose conc 60-70% of plasma glucose (but no longer applies once >600 mg/dL)
Hypoglycorrhachia
Decreased CSF glucose levels
Causes of hypoglycorrhachia + examples
- Disorder in carrier-mediated transport of glucose into CSF
- Active metabolism of glucose by cells/organisms
- Increased metabolism by CNS
- Examples: meningitis, meningeal neoplasia, brain tumor
Consumption of glucose usually has increased _____ level due to ______ glycolysis by organisms or tissue
Lactate
anaerobic
What do CSF protein levels reflect?
Selective ultrafiltration of CSF blood-brain barrier
Total protein conc in CSF
0.5%-1.0% of plasma
Not proportional due to specificity of ultrafiltration process
Which analysis should accompany CSF protein analysis?
Serum
Causes of decreased protein CSF
- Decreased dialysis of proteins from plasma
- Increased protein loss (removal of excessive volumes of CSF)
- Leakage from a tear in the dura, CSF otorrhea (ear), or CSF rhinorrhea (nose)
How to detect CSF leakage
Analysis of beta-transferrin bc it’s unique to CSF
Causes of increased protein in CSF
- Lysis of contaminant blood from traumatic tap
- Increased permeability of epithelial membrane
- Increased production by CNS tissue obstruction
How do bacterial/fungal infections affect the BBB?
Increase permeability
T/F: Protein in CSF is NOT diagnostic of infectious meningitis - helpful though
True
Normal CSF and serum prealbumin conc. Why is it measured in both?
- CSF > serum conc
- Used to normalize IgG values to determine source
Describe proteins of highest interest in CSF
- Albumin: must cross BBB
- IgG: Can be produced by local synthesis from plasma cells within the CSF
Index value of protein which indicates intact BBB
protein index < 9
IgG index
How to calculate
What does it help diagnose
Normal value
- Use CSF serum index
- Helps diagnose demyelinating diseases (MS, SSPE)
- Normal IgG < 0.73
How does serum albumin affect CSF levels?
Increases CSF levels due to membrane permeability