Cerebrospinal Fluid (CSF) Exam

CSF (Cerebrospinal Fluid)

• Protects the brain from sudden changes in pressure, maintains a stable chemical environment, and removes waste products of cerebral metabolism
• Normal adult volume: 100-200 ml

CSF Exam

• Indications:
  • Urgent: subarachnoid hemorrhage, CNS malignancy
  • Selective: meningial infection, demyelinating disease
• Sample: lumbar puncture or ventricular canula
• Macroscopic exam:
  • Normal CSF: clear colorless, clot-free, viscosity of water
  • Turbidity: RBCs > 400/ul, WBCs > 200/ul, increased protein level, microorganism
  • Clot formation: traumatic tap, TB meningitis

CSF Microscopic Exam

• Normal WBCs: 0-5 cells/ul, mostly lymphocytes and RBCs 0-5 cells/ul
• Microbiological exam:
  • Bacteriological
  • Serological

CSF Chemical Exam

• Total protein: normal 20-40 mg/dl
  • Increase: traumatic, toxic, tissue degeneration
  • Decrease: leakage of CSF, increased intracranial pressure, hyperthyroidism
• Glucose: normal 40-80 mg/dl
  • Increase: hyperglycemia
  • Decrease: bacterial meningitis, TB, fungal, viral
• Lactate:
  • Normally parallels blood concentrations
  • Increased in intracranial hemorrhage, epilepsy, and bacterial meningitis
• Xanthochromia:
  • Yellow or pink discoloration of CSF, indicating presence of hemoglobin degradation products
  • Indicates blood has been in CSF for at least 2 hours (e.g. subarachnoid hemorrhage)

Serous Fluids

• Peritoneal fluid:
  • Definition: fluid lining abdominal and pelvic cavity
  • Types: transudate (congestive HF, liver cirrhosis, hypoproteinemia) and exudate (infection, trauma, tumor, chylous effusion)
  • Sample: paracentesis, normal amount 50-100 ml
  • Indications: diagnostic (ascites, internal perforation, abdominal hemorrhage) and therapeutic (treatment of malignancy)

Urine Analysis

• Overview:
  • Indications: routine check-up, diagnosis, and follow-up
  • Sampling: random (mid-stream urine), first morning sample, 24-hour collection
• Examination:
  • Physical: color, volume, specific gravity
  • Chemical: pH, protein, glucose, ketone
  • Microscopic: RBCs, pus cells, casts

Urine Physical Exam

• Color: normal yellow
• Volume:
  • Anuria: 24-hour output below 100 ml
  • Oliguria: 24-hour output below 500 ml
  • Polyuria: 24-hour output above 3000 ml
• Specific gravity: normal 1.005-1.030
  • High: glucosuria, proteinuria, and disorders associated with oliguria
  • Low: polyuria (except in diabetes mellitus), cases of oliguria with low specific gravity
  • Fixed: chronic renal disease

Urine Chemical Exam

• pH: normal 4.5-8.0
• Protein: normal 100-150 mg/24h
  • Glomerular proteinuria: nephrotic syndrome
  • Tubular proteinuria: pyelonephritis
  • Transient proteinuria: physical exertion, trauma, etc.
• Glucose: normal 20-200 mg/24h
  • Causes of glucosuria: hyperglycemia, renal glucosuria
• Ketone: causes of ketonuria: prolonged fasting, severe vomiting or diarrhea, diabetic ketoacidosis

Urine Microscopic Exam

• RBCs: acute glomerulonephritis, stones, trauma of the urinary tract, malignancy of the urinary tract
• Pus cells: urinary tract infections
• Casts:
  • Red cell casts: acute glomerulonephritis
  • Pus cell casts: pyogenic kidney
  • Granular casts: chronic glomerulonephritis, chronic renal failure
  • Waxy casts: late nephrosis