Cerebrospinal Fluid

What is cerebrospinal fluid?

clear fluid that bathes the brain and spinal cord.

What parts of the lab or involved in CSF?

microbiology, hematology, and chemistry departments

What age group predominates when handling CSF specimens?

infants and children - they are more susceptible to meningitis

How are CSF specimens collected?

3 or 4 sterile tubes - totaling 5-10 mL

What is the minimum you should keep CSF?

2 weeks

Delivery of CSF tubes?

Tube 1 goes to Chemistry; tube 2 goes to Microbiology and tube 3 goes to Hematology

How is CSF routinely collected?

by lumbar puncture between the third, fourth, or fifth lumbar vertebra

The volume of CSF that can be removed is based on?

the volume available in the patient (adult vs. neonate) and the opening pressure of the CSF

How is CSF pressure measured?

when the needle first enters the subarachnoid space

How are the tubes to be labeled?

In the order in which they are drawn

Tube 1 is used for chemical and serologic tests because?

these tests are least affected by blood or bacteria introduced as a result of the tap procedure

Tube 3 is used for the cell count, because it is the?

least likely to contain cells introduced by the spinal tap procedure

Will a fourth tube sometimes be drawn?

Yes - for microbiology laboratory to better exclude skin contamination or for additional serologic tests

The supernatant fluid this is left over after each section has performed its tests?

may also be used for additional chemical or serologic tests

Should you discard excess spinal fluid?

No - should be frozen until there is no further use for it

How are CSF tests performed?

STAT

If STAT testing is not possible, specimens are maintained in the following manner?

1. Hematology tubes are refrigerated
2. Microbiology tubes remain at room temperature
3. Chemistry and serology tubes are frozen

CSF that is clear or crystal clear?

Normal

CSF that is cloudy, turbid, or milky?

may result from increased protein of lipids or infection (due to WBCs)

What is xanthochromia?

used to describe pink, orange, or yellow CSF supernatant; usually caused by RBC degradation products

Pink CSF?

represents a very slight amount of oxyhemoglobin

Orange CSF?

represents heavy hemolysis

Yellow CSF?

represents oxyhemoglobin that has been converted to unconjugated bilirubin

Less common causes of xanthochromia are?

increased serum bilirubin, carotene pigment, increased protein concentration, and melanoma pigment

What is traumatic collection?

when a blood vessel is punctured during the tap causing fresh RBCs to get into the sample

What can make it grossly bloody, which has nothing to do with a traumatic tap?

result of intercranial or subarachnoid hemorrhage

What 3 things will differentiate between a traumatic collection and a intercranial/subarachnoid hemorrhage?

1. uneneven distribution of blood in fluid
2. clot formation
3. the absence of xanthochromia - all of these indicate a traumatic puncture

How long do RBCs have to be present in CSF for xanthochromia to be present?

at least 2 hours

What cell counts are normally performed?

WBC
RBC counts are done only if traumatic tap takes place to correct for WBCs and protein

WBCs and RBCs will begin to lyse?

as early as 1 hour after the tap

If tests cannot be performed immediately, the CSF should be?

refrigerated

Normal adult CSF contains ? of WBC?

0-5 WBC/uL (higher in children and newborns) Newborns may have up to 30 mononuclear cells/uL

Formula used for determining the number of cells/uL?

# of cells counted X dilution / # of squares counted X volume of 1 square = cells/uL

Shortcut method for counting?

count five (.1 uL) squares on each side of Hemocytometer [10 squares (1.0uL) total] and multiply the # of cells counted by the dilution = cells/uL

Total cell counts are diluted by?

normal saline

WBC counts require?

lysis of RBCs

Lysis of and counting of RBCs can be done by using?

3% acetic acid or toluidine blue O (stain) and saponin (lysing agent); the later stain assists in the ID of WBCs

RBC count?

total cell count minus the WBC count equals the RBC count

QC must be done?

with controls (in-house or commercial) with each test, daily or on each shift depending on how often the lab performs them

Diluents must be checked?

periodically for contamination and the speed and timers of cytocentrifuges (if used) must be checked

Nondisposable equipment must be?

(counting chambers, pipettes, etc.) must be disinfected to prevent possible infections

The differential count should be done?

on a stained smear not on the hemacytometer

What can reporting only the mononuclears and PMNs possibly cause?

preventing the ID of cells that may help in diagnosis

Smears should be made from?

concentrated specimens

How can concentrated specimens be made?

filtration, sedimentation, routine centrifugation for 5-10 minutes (poorest method) and cytocentrifugation (best method)

How many cells should be used? If you have a low count?

100 cells - differentiated by %
low counts - report only the #'s and types of cells seen if 100 cells cannot be found

Normal CSF contains primarily small #'s of?

lymphocytes and monocytes

Adults have more ? while children have more ? percentage wise?

lymphs - monos

Is it considered a normal specimen if you seen an occasional neutrophil?

yes

An increase in CSF normal cell types is termed?

pleocytosis

What cells are considered abnormal in CSF?

immature leukocytes, eosinophils, plasma cells, macrophages, increased tissue cells, and malignant cells

A high CSF WBC with the majority of cells being neutrophils is indicative of?

bacterial meningitis

A moderately elevated CSF WBC with a high percentage of lymphs and monocytes suggest?

meningitis of viral, tubercular, fungal, or parasitic origin

A low cell count below 25 cells/cubic mL with increased lymphs may be indicated of?

multiple sclerosis

What are seen after repeated taps because of the introduction of RBCs into the CSF?

macrophages

What cells are not clinically significant and why?

ependymal and choroid plexus cells - they line the CNS

Seen in parasitic infections, reactions to foreign material and shunts?

eosinophils

Plasma cells and reactive lymphs are associated with?

viral infections and multiple sclerosis

Is there a possibility to see bacteria and budding yeast in CSF?

yes

Should abnormal cells be included in the report?

Yes and reviewed/confirmed by the pathologist

The chemistry tests ordered most often are?

T. protein, glucose, chloride, gamma globulin, and sometimes enzyme tests

The protein concentration in CSF?

15-45 mg/dL

Increase in CSF protein?

any damage or inflammation to the membranes covering the brain or spinal cord - allows plasma proteins or cell proteins to cross the blood brain barrier

Total protein's increase is?

directly related to the amount of damage or severity

Severe meningitis may cause protein concentrations to exceed?

500 mg/dL (Blood and pus will also increase T. protein)

The concentrations of T. protein and gamma globulins usually rise in the following non-purulent conditions:

encephalitis, tuberculosis meningitis, syphilitic meningitis, and multiple sclerosis

Methodology of CSF protein measurement?

utilizes the principle of turbidity production where sulfosalicylic acid or trichloroacetic acid (reagent of choice) can be used to precipitate protein

The dye-binding technique utilizes?

coomassie brilliant blue dye - binds a variety of proteins and not just albumin - dye turns red to blue when it binds protein; more protein the darker the blue

The standard biuret methods utilized?

measure serum protein - not sensitive enough for the much lower CSF protein

It is fairly simple to determine whether the increase in CSF protein is from proteins crossing a damaged blood-brain barrier because?

protein fractions in CSF are proportional to those in the plasma where albumin will be in the highest concentration

CNS producing a particular immunoglobulin, such as IgG?

multiple sclerosis

By comparing the IgG/albumin ratio for both serum and CSF (CSF IgG/serum IgG compared to CSF albumin/serum albumin), when IgG ratio is higher than albumin ration, means the increase in IgG in the CSF is from?

cells within and has not diffused across a damaged membrane

CSF albumin and globulins can be done by?

radial immunodiffusion, nephelometry or electrophoresis

Nephelometry will give?

individual fractions

Electrophoresis will give?

visualization of bands/fractions but requires a minimum of 100 fold concentration; allows visualization of oligoclonal banding which shows up in the gamma region and is indicative of inflammation

Two or more oligoclonal bands present in CSF but NOT the patient's serum is valuable in the diagnosis of?

multiple sclerosis especially when the IgG index is increased as well

Increases with myelin sheath destruction and can be tested to monitor multiple sclerosis?

Myelin Basic Protein

CSF glucose levels?

about 60-70% of the level which it is in the plasma; in equilibrium with it

Is there a lag between what the plasma glucose level is and the CSF glucose level?

Yes - about a 2 to 3 hour lag

The normal CSF glucose varies with the serum level but if the patient's glucose falls within the normal range, their CSF should?

fall within a range of 40-70mg/dL taking into consideration the 60-70% factor

With a normal plasma glucose, CSF glucoses will generally be less than 30 mg/dL in various types of?

bacterial meningitis; whereas, viral meningitis will have no effect on the glucose

Decreased CSF glucose is primarily a result of alterations in the mechanisms of?

decreasing glucose transport across the blood-brain barrier, by increased utilization of glucose by the brain cells, and to some extent utilization by bacteria and leukocytes

CSF chloride?

may be ordered sometimes but yields very little useful information

CSF chloride is about 20% higher than?

plasma chloride

CSF lactate ranges?

10-24 mg/dL

CSF lactate increases above 25 mg/dL occur?

more consistently with bacterial, tubercular and fungal meningitis than decreased CSF glucose; monitor head injuries where rises are indicative of decreased oxygen to the brain tissues

CSF lactate decreases rapidly when?

antibiotic therapy is working which helps doctors to evaluate treatments faster

What will cause false elevations of CSF lactate?

xanthochromic or hemolyzed specimens due to lactates presence in RBCs

CSF glutamine ranges?

8-18 mg/dL

CSF glutamine in an?

indirect measure of excess ammonia in the CSF because when CSF ammonia is increased, CSF glutamine is synthesized to help remove the toxic ammonia

Why is CSF glutamine measuring preferred over CSF ammonia?

due to glutamine's stability and ammonia's volatility

CSF glutamine is very valuable in assessing?

comas of unknown origin since high levels of CSF ammonia can cause them

75% of these cases will be positive for CSF glutamines?

Reye's Syndrome suspected

Even though not ordered often, CSF enzymes can be helpful in determining?

the amount of brain tissue damage

What enzyme would you look for when testing CSF for enzymes?

LD isoenzymes (LD1 and LD2 - brain tissue) (LD2 and LD3) (LD4 and LD5 - neutrophils)

Elevated CSF CK BB levels after resuscitation from cardiac arrest indicates a?

poor prognosis

Should be performed on all CSF specimens?

gram stain

CSF specimens must be concentrated by?

centrifuging at 1500g for 15 minutes

The concentrate, after centrifuging, should be used for?

both gram stain and innoculating the culture media

Used when tubercular meningitis is suspected?

Acid Fast or Fluorescent Antibody stains