Clinical chemistry(MLCC-203)

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Presented by: Dr.Eman El-Attar

MLC-203

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Define CSF and its formation .

Recognize physiological functions.

Define lumbar puncture why and how?

Examine CSF: physical, chemical, microscopic.

Interpret tests results.

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•Cerebrospinal fluid (CSF) is mostly derived the choroid plexuses by ultrafiltration and active secretion.

•CSF flows through the subarachnoid space between the arachnoid and pia mater

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It is about 90-150 ml

2005-5-17Medicine School of Shandong

University

Functions

1.To supply nutrients to the nervous system

2.To remove metabolic wastes

3.To produce a mechanical barrier to cushion the brain and spinal cord against trauma.

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Specimen Collection and handling

CSF is collected by lumbar puncture between third, fourth, fifth lumbar vertebrae.

It requires certain precautions and careful technique to prevent the introduction of infection or the damaging of neural tissue.

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CSF is collected in three sterile tubes

• Tube 1 – used for chemical and serologic test: centrifuge and use supernatant for chemistry analysis (glucose, protein, chloride)

• Tube 2 – used for microbiology lab

• Tube 3 – used for hematology (cell count) Cell counts done as soon as possible after the fluid is collected as cellular degradation occurs rapidly. If postponed, refrigerate

for up to one hour.

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Indications: Meningitis, demeylinating disease ,

meningeal involvement in malignant disease

Contraindications: INR > 1.5 Platelets < 50,000 intracranial mass partial / complete spinal block acute spinal trauma

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Post-lumbar puncture Headache.

Bleeding; spinal hematoma.

Infection (poor sterile technique)

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Aspect: Crystal Clear color and viscosity comparable to water

< 5 RBCs / mm3

< 5 WBC’s / mm3

Protein : 15-45mg/dl

Glucose : 60% of serum level (75-100)

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Abnormal appearance

• Cloudy or turbid: • increased protein or lipids• presence of WBC

• Hemolyzed or bloody:• Traumatic tap• Tumor or hemorrhage

• Xanthochromic:• Slight hemolysis• Jaundice• Marked increase in proteins

• Clot formation: • traumatic tap• meningitis

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Should be examined 1 Hr or less after collection to differ between cell lysis before or after collection.

2005-5-17Medicine School of Shandong

University

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RBCs: Always send tube #1 and #3 for cell count and compare RBCs

Traumatic tap: RBC in tube 1, nil in tube 3• RBC : WBC ratio should be the same as in blood

(approx 1000 RBC : 1 WBC)• In the CBC (RBCs are in millions and WBCs are

in thousands)

Subarachnoid Hemorrhage : RBC in tube 1 AND tube 3• “Crenated RBCs” and xanthochromia (yellow supernatant

after centrifuge)

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WBC count

Performed promptly as 40% of leukocytes may lyse after 2 hrs at room temp

Normal adult 0 – 5 WBCs/µL Children 30 mononuclear cells/µL

( 200WBC/ 400RBCs)-DIFFERENTIAL COUNT ON A CSF SPECIMEN It should be performed on a stained smear and not from the cells in the counting chamber.

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CSF WBC > 1000, PMN predominance

CSF protein > 500mg/dlCSF glucose < 45 mg/dl

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CSF WBC elevated, but < 250 (PMNs in early disease, then lymphocytes)

CSF protein elevated, but < 150Glucose > 50% of serum concentration

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Glucose: Blood glucose should be drawn simultaneously. The normal glucose is about 60% compared to

serum level. Normal 50~80mg/dl Elevated Glucose: within 2 hrs preceeding

lumbar puncture. (Diabetes mellitus) Decreased Glucose: Systemic hypoglycemia, Bacterial Meningitis, TB meningitis,

amoebic meningitis

2005-5-17Medicine School of Shandong

University

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Over 80% of CSF protein content is derived from the plasma by ultrafiltration.

Normal level 15~45mg/dl.

In premature and full term neonates it reach up to 130mg/dl and 120 mg/dL respectively.

Determination of protein to assess permeability of BBB or intrathecal synthesis of protein.

2005-5-17Medicine School of Shandong

University

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Increased permeability of the blood-brain barrier dt brain tumour, intracranial hemorrhage, traumatic injury.

Increased intrathecal synthesis of IgG as in Multiple schlerosis

Mechanical obstruction of CSF flow above the puncture site.

2005-5-17Medicine School of Shandong

University

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ArachnoiditisMeningitisHemorrhageEndocrine/Metabolic disorders

2005-5-17Medicine School of Shandong

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Less than 10mg/dlDt- CSF leakage from dural tear.

-Hyperthyroidism

2005-5-17Medicine School of Shandong

University

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Determination of total protein by: -Turbidimetric method.(need big volume) -Dye binding method by CBB underestimate

globulins. - Immunochemical methods. Determination of specific proteins by: -Electrophoresis. - Immunoturbidimetry - Nephelometry. - RID - RIA - ElectroimmunodiffusionPandys test for globulin determination

2005-5-17Medicine School of Shandong

University

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CSF albumin (mg/dl)/ Serum albumin(g/dl) Index.

Index less than 9= intact barrier

2005-5-17Medicine School of Shandong

University

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CSF LACTATEIn neonates (10-40mg/dl) . In adult or older children (10-22 mg/dl) It refers to anaerobic metabolism.

It increase in bacterial, tubercular and fungal meningitis. Not in viral meningitis.

Brain abscess-Intracranial hge- hypoxia-hydrocephalus-traumatic brain injury.

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CSF GLUTAMINE

Glutamine is produced in the CNS by the brain cells from ammonia and alpha-ketoglutarate. This process serves to remove the toxic metabolic waste product ammonia from the CNS.

Elevated levels associated with liver failure,septic encephalopathy , respiratory failure.

2005-5-17Medicine School of Shandong

University

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LDH – LD1, LD2, LD3, LD4, LD5%: -Increase LD5 in metastatic brain tumor. -Increase all fractions in 1ry brain tumor. -Increase LD4,LD5 in bacterial meningitis.

CK – BB: -Increase in: epileptic patient Brain tumor cerebral infarction

2005-5-17Medicine School of Shandong

University

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MICROBIOLOGY TESTGRAM STAIN

Is routinely performed on CSF from all suspected cases of meningitis although its value lies on the detection of bacterial and fungal organisms.

Organisms most frequently encountered:

S. pneumoniae (gram positive cocci) H. influenzae ( pleomorphic gram negative rods)

E. coli (gram negative rods)

Urine examinationBy: Reham shalaby, Sura Iftekhar

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-How many tubes of CSF should be collected for CSF examination?

-What are the chemical analytes done to a CSF sample

-What abnormal findings suggest a traumatic tap?

2005-5-17Medicine School of Shandong

University

372005-5-17Medicine School of Shandong

University