Renal Function Tests & CSF

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Renal Function TestsRenal Function Tests

1. Urine routine examination: appearance, volume, spgravity, pH, glucose, protein and sediment.

2. Blood urea conc.

Blood urea nitrogen (BUN).

3. Serum creatinine conc..

4. Clearance tests to measure the GFR.

a. Inulin clearance test.b. Creatinine clearance test.

c. Urea clearance test.

5. Serum electrolytes (Na, K, Cl, HCO).

6. Urinary total protein, Microalbumin.7. Other Investigations.

USG of kidneys.

X-ray KUB, IVU, CT Scan.

Renal biopsy (FNAC).


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Blood UreaBlood Urea

Urea in blood is mostly derived from catabolism of

protein. It is freely filtered through glomeruli.

It is passively reabsorbed from the filtrate.

Its blood conc. may rise due to increased production,

decreased filtration or increased reabsorption. Normal blood conc. is 15 50 mg/dl of blood.

BUN is the nitrogen derived from protein breakdown

only. It is calculated as:

Urea X 28/60 = BUNBUN X 60/28 = Urea


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Serum CreatinineSerum Creatinine

Creatinine is derived from creatine.

Its blood conc. depends on total muscle mass.

It is filtered freely through glomeruli.

It is not reabsorbed from the filtrate.

Small amount of it is secreted by the tubules.

Its blood conc. rises due to decreased filtration andincreased production.

Normal blood conc 0.6-1.2 mg/dl of blood.


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Clearance testsClearance tests

Clearance test measures the volume of plasma

completely cleared of a substance per minute. Itis a measure of GFR.

Inulin clearance test is the most ideal but a littledifficult to perform. Most convenient and usefulis the creatinine clearance test.

Clearance of a substance (GFR) is calculatedusing the following formula:

Clearance (GFR) = Conc. in urine X 24 hrs urinevolume/ Conc. in blood X Collecting time in min.

Normal creatinine clearance is:Adults < 55 yrs: 95 145 ml/min.

Clearance decreases progressively with age.


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C S F


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Examination of CSFExamination of CSF

Introduction: Cerebrospinal fluid is formedfrom plasma by the filtering & secretory activitiesof the choroid plexus in the lateral ventricles. Itpasses through the third & fourth ventricles into

the subarachnoid space between the pia mater& arachnoid mater, & completely surrounds thebrain & spinal cord. CSF is reabsorbed into theblood stream by the arachnoid villi which projectinto the subarachnoid space.

In the adult the total volume of CSF is about 140ml.


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CSF STYDYCSF STYDY

Functions of CSF:

The CSF supports the brain &

protects it against injury. It also has asimilar function to lymph & remove waste

products of metabolism.


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Laboratory Examination Of CSFLaboratory Examination Of CSF

It includes the following examination:

*A. Physical Examination

*B. Chemical Exam.

*C. M/E

*D. Bacteriological Examination.

*E. Other tests.


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Physical ExaminationPhysical Examination

* Appearance: Normal CSF is clear.

* Colour: Colourless.

* Clot: Normal CSF does not clot.


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Cell CountCell Count

Normal: 0-5 lymphocytes/cmm.


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Chemical ExaminationChemical Examination

1. Protein: Normal: 15- 45mg/dl.

2. Glucose: Normal: 50-70mg/dl.

3. Chloride: Normal: 710-750mg/dl.


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Bacteriological ExaminationBacteriological Examination

Normal CSF is sterile.

1. Smear of centrifused deposit.

2. Culture.


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Other testsOther tests

1. VDRL

2.Antigen detection

3.Immunologial tests &

Electrophoresis.


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MeningitisMeningitis

Bacterial

1. 1st 06 wks

Enteric gram neg

Group B strept

Meningococci

Staph

Pneumococci L.monocytogens

Group A strept


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MeningitisMeningitis

2. Six wks to six yrs

H. influnzae

Meningococci Pneumococci

3. Over six yrs

Pneumococci

Meningococci

4. All ages: Tuberculosis


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CSFCSF

3.Fungal causes

Cryptococcosis

AspergillosisHistoplasmosis

Mucormycosis


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CSF in normal health & common disordersCSF in normal health & common disorders4.Protein(

mg/dl)

15-45 Increased

500-2000

Increased

500-3000

Increased

500-2000

Normal Increased

500-2000

5.Glucos

e(mg/dl)

50-70 May

disappear

Decrease

d 20-30

Normal Normal Normal

6.Chlorid

e(mg/dl)

710-750 Normal


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CSFCSF

Indication of CSF study

Meningitis

Subarachnoid haemorrhageMalignancy

Demyelinating disease

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Renal Function Tests & CSF