CSF AND OTHER BODY FLUIDS

brain and spinal cord

What structures make up the CNS?

meninges and the Blood-Brain Barrier (BBB)

protective barrier of the cns

Blood-Brain Barrier (BBB)

composed of the choroid plexus and capillaries

Cushions and protects the brain
Provides buoyancy
Delivers nutrients/metabolites
Removes CNS waste
Maintains CNS homeostasis

What are the primary functions of CSF?

1. Obtain informed consent

2. Position patient (fetal or sitting)

3. Identify site (between L3–L4)

4. Sterilize with alcohol and iodine

5. Insert needle, collect 3-4 tubes:

   1. Tube 1: Chemistry

   2. Tube 2: Microbiology

   3. Tube 3: Hematology

   4. Tube 4: Additional tests

What are the steps in proper lumbar puncture for CSF collection?

Chemistry/Serology: Freeze
Hematology: Refrigerate
Microbiology: Room temp
Viral Studies: -70°C (or refrigerate if processed within 24 hrs)

How should CSF be stored based on the test?

Presence of WBCs, bacteria, increased protein or lipids.

What does a turbid CSF indicate?

xanthochromia

Yellow/orange/pink discoloration due to RBC lysis, high CSF protein (>150 mg/dL), or traumatic tap.

Traumatic Tap

Blood diminishes in subsequent tubes

Hemorrhage

Blood present in all tubes

Infections, hemorrhages, MS, Guillain-Barré, malignancy

What causes elevated CSF protein?

Chronic leak, acute water intoxication

What causes low CSF protein?

Bacterial and fungal infections consume glucose, lowering CSF levels. Viral infections often show normal glucose.

How does infection affect CSF glucose?

0-5 WBC/uL (mostly lymphocytes)

typical wbc count in csf for adults

0-20 WBC/uL (monocytes and some PMNs)

typical wbc count in csf for newborn

Bacterial Meningitis

Glucose 20 mg/dL, Protein 150 mg/dL, WBC 250/uL (Neutrophils)

Tubercular/Viral Meningitis

Glucose 55 mg/dL, Protein 70 mg/dL, WBC 100/uL (Lymphocytes)

Gram stain: bacteria
Acid-fast: TB
India ink: Cryptococcus
Giemsa/Wright: Toxoplasma

What stains are used for specific organisms in CSF?

Transudates

Clear, low protein/glucose, few cells, low SG (<1.018)

Exudates

Turbid, high protein/glucose, many cells (PMNs), high SG (>1.018)

PF/serum protein > 0.5
PF/serum LDH > 0.6
PF LDH > ⅔ upper normal serum LDH

What is Light’s Criteria for exudates?

In TB, malignancy, RA, empyema, lupus, etc

When is pleural glucose <60 mg/dL significant?

Pancreatitis, esophageal rupture, malignancy

High amylase in pleural fluid suggests what?

Neutrophils: Acute bacterial
Lymphocytes: TB, malignancy
Eosinophils: Air/blood in pleura, allergy

What WBC patterns help with diagnosis in pleural fluid?

Zollinger-Ellison syndrome, recurrent PUD, achlorhydria, delayed emptying, GI bleeding

What are indications for gastric fluid testing?

1.6-1.9
20-50 mL

Normal pH and fasting volume of gastric fluid?

Gunzberg: Phloroglucinol → purplish red
Boas: Resorcinol → rose red
Dimethylaminoazobenzole: Cherry red

What tests detect HCl in gastric fluid?

Gastric cancer (due to bacterial fermentation)

What does elevated gastric lactic acid suggest?

Pus cells: Gastritis, abscess, CA
RBCs: Ulcer
Columnar epithelial: Gallbladder disease
Yeast/bacteria: Infection or contamination

What are key cells seen in gastric microscopy and their implications?

None Apelt reaction

Qualitative chemical test that will detect bile salts

Pandy’s test

Qualitative test to detect proteins particularly globulins in CSF

adult: 15-50 ml/dL, newborn: 15-170 ml/dL

total protein reference range

adult: 40-80 mg/dL, newborn: 30-120 mg/dL

glucose normal value

adult: <= 5-10 (lymphocyte), newborn: 0-30 (monocyte)

leukocyte count normal value

Coomasie brilliant blue G250

Bind to a variety of proteins
Used in dye binding techniques