UA and body fluids- 3.1 CSF

CSF

within subarachnoid space of the entire CNS

CSF formed by

selective filtration of the plasma and active transport secretion by epithelial membrances

CSF volume in adults

80-150 mL

CDF in infants

10-60mL

CSF functions

• provides nutrients to nervous tissue

• remove metabolic wastes

• maintain intracranial pressure

• mechanical barrier to cushion the brain and spinal cord

How do you obtain CSF specimen?

lumbar puncture

CSF is aliquoted into at least 3 sterile tubes

tube 1= chemistry

tube 2= microbiology

tube 3= cell count

tube 4= additional testing

-if only 1 tube or syringe is collected, use for micro first

CSF appearance: normal

colorless and clear

CSF appearance: hazy/cloudy/turbid

-increase protein

-increase lipid

-increase WBC (could indicate meningitis

CSF appearance: pink or red → intracranial bleed

consistent color/cell count among all tubes and no clotting

CSF appearance: pink or red → traumatic tap

gradual decrease of color/cell count from first tube to last

-may form clots

CSF appearance: xanthochromia

yellow/amber/orange; caused by hemoglobin degradation products due to older intracranial bleed or elevated serum bilirubin

CSF normal cell count

0-5 WBC/ uL in adults

<30 WBC/uL in newborns

0 RBC/uL

hemocytometer

for manula CSF cell count and has neubauer counting chamber

automated count

hematology analyzers have “body fluid mode” to count smaller amount of cells

normal cytospin concentrated slide

primarily lymphocytes

-adults 70:30 lymphs to monos

-children 30:70 lymphs to monos

CSF differential: increase in neutrophiles

bacterial meningitis

CSF differential: increase in lymphs/mono

viral meningitis

CSF differential: macrophages present

previous hemmorhage

CSF differential: malignant cells

may be of hematologic origin, metastatic carcinomas, CNS tumors

CSF chemistries: abnormal values due to

alternation in permeability of blood-brain barrier; increased metabolism by neural cells in response to pathological condition

normal CSF protein

15-45 mg/dL

-method dependent

low CSF protein

leakage

high CSF protein

meningitis; hemorrhage damaging blood-brain barrier

normal CSF glucose

60-80% of plasma glucose

-should be compared to blood glucose result

low CSF glucose with increase in WBC with neutrophils

bacterial meningitis

low glucose without increase in WBC

alteration of transport across blood-brain barrier

-increase glucose metabolis by brain cells

high glucose

always due to increased plasma glucose

CSF additional tests

lactate, gram stain and culture, molecular testing, serological testing