KIDNEY FUNCTION TESTS Stage 5: GFR less than 15 (Kidnet failure, requires

dialysis)
Functions:
• Regulation of Homeostasis
• Electrolytes 2. Serum Creatinine
• Water A serum creatinine blood test measures the level
• Acid-base balance
of creatinine in the blood.
• Retention of substances vital to the body such as
proteins and glucose • Creatinine is the breakdown product of
• Excretion of waste products, water soluble muscle creatinine phosphate and creatine . It
substances and drugs is excreted in the urine
• Synthesize hormones • Serum creatinine provides a more sensitive
 Erythropoietin measure of renal damage than blood urea
 Renin • Creatinine level is directly related to the
 Calcitriol
Glomerular Filtration Rate
 Prostaglandins
• Method: Jaffe Reaction (red-orange solution)
Tests of Kidney Function • Normal Values
1. Glomerular Filtration Rate (GFR) 0.8 to 1.2mg/dl in Male
2. Serum Creatinine 0.6 to 0.9mg/dl in Females
3. Creatinine Clearance *Females have lower creatinine level than
4. Blood Urea Nitrogen (BUN)
males due to less muscle mass
5. Blood Uric Acid

1. Glomerular Filtration Rate Increased serum creatinine:

• GFR is the rate at which substances in • Renal dysfunction
plasma are filtered through the glomerulus • Excessive exercise
• It is the best single measure of kidney function • Hyperthyroidism
• A normal GFR (~125ml/min) is presumptive of • Drugs (i.e Aspirin, Aminoglycosides,
healthy, functioning kidneys.
Cimetidine)
• As GFR declines (renal function declines), urinary
excretion of urea and creatinine also Decreased serum creatinine:
declines and blood concentration of both • Cachexia
increases. • Cirrhosis
• Myasthenia gravis
Formulas used to estimate GFR • Drugs (Neuromuscular blocking
• Cockroft – Gault Formula agent)
• Modification of Diet in Renal Disease (MDRD)
Formula 3. Creatinine Clearance
• CKD-EPI (Chronic Kidney Disease Epidemiology • Creatinine clearance represents the
Collaboration) Formula amount of blood per minute at which
creatinine is removed from the blood
Glomerular Filtration Rate
by the kidneys and roughly
• GFR Staging System for Kidney Disease
Stage 1: GFR 90 or greater (normal kidney approximates the GFR
function) • It helps physicians determine dosage
Stage 2: GFR 60-89 (mild decline in kidney adjustment for renally eliminated
function) drugs
Stage 3a: GFR 45-59 (mild to moderate decline in • Creatinine clearance can be precisely
kidney function determined by measuring the amount
Stage 3b: GFR 30-44 (moderate to severe decline of creatinine present in as sample of
in kidney function urine collected over 24 hours.
Stage 4: GFR 15-29 ( severe decline in kidney
function) 4. Blood Urea Nitrogen
 • Urea is an end product of protein
metabolism produced in the liver
• BUN measures the urea nitrogen in
the blood
• ! Enzymatic method: Berthelot
Method
• Normal values for BUN range from 8mg/dl to
18mg/dl LIVER FUNCTION TESTS
 The largest gland
HIGH BUN signifies liver disease  The right lobe is 6x larger than the left
• Malnutrition lobe
• Profound liver damage
 The liver is an extremely vascular organ
• Fluid overload
 1500 mL blood passes throughthe liver
• Drugs (Chloramphenicol, Streptomycin)
per minute
Function:
LOW BUN signifies kidney disease
1. Excretion/ Secretion
• Acute Renal Failure
2. Metabolism
• Chronic Renal Failure
3. Detoxification
• Blood loss
4. Storage
• High protein diet
• Drugs ( Allopurinol, Corticosteroids)

5. Blood Uric Acid

• Uric Acid blood test also known as serum
uric acid measurement, determines how
much uric acid is present in your blood.
• Uric acid is a chemical produced when your
body breaks down food that contains
organic compounds called purines. (i.e liver,
anchovies, beans) Fig.1 Lobules are the functional unit of
• Most uric acid is dissolved in the blood, the liver
filtered though the kidneys and expelled in
Total Protein and Albumin/Globulin Ratio
urine.
This is a blood test to measure the levels
• The test is most commonly used to: of protein in your body. It also provides
 Diagnose and monitor people with gout information about the amount of albumin
 Monitor people undergoing you have compared with globulin. This
chemotherapy comparison is called the A/G ratio
 Check kidney function after an injury
 Find the cause of kidney stones This routine medical test helps evaluate
 Diagnose kidney disorders the body nutritional status, is a key
! Chemical method: Phosphotungstic acid indicator for the performance of liver and
method kidneys in the body, and can aid in an early
! Enzymatic method: Uricase method detection of certain diseases
Uric acid levels can vary based on sex. Normal
Proteins: These are important building
values for women are 2.5 to 7.5mg/dl and for
blocks of the body and are vital for body
men 4.0 to 8.5 mg/dl.
health. Albumin and Globulin are two types
of plasma proteins found in the blood.
 Total Proteins benzoic acid)
- BCG (bromcresol
green)
 The specimen most often used is serum - BCP (Bromcresol
rather than plasma. purple)
3. Electrophoresis Proteins separated Accurate; gives overview
based on electric of relative changes in
 Fasting specimen is not needed. charge different protein
franctions.
 Interference occur in the presence of
lipemia.

 Reference interval for ambulatory adults 6.5-

8.3 g/dL; in the recumbent position 6.0 to 7.8 Globulins are proteins produced by the liver
g/dL and the immune system

Method Principle There are four groups namely α1,α2, β, and γ

Functions
Kjeldahl Digestion of protein; Reference method;
a) Fights infection
measurement of assume average
b) Transport nutrients
Reference Range: 2.3-3.5 g/ dL
nitrogen content nitrogen content of
16 %
*Globulin is calculated by subtracting the
measured albumin from the measured total
protein.
Biuret Formation of violet- Routine method; ! Globulin = Total Protein - Albumin
color red chelate requires at least two
between Cu2+ ions peptide bonds and an Albumin/Globulin Ratio:
and peptide bonds alkaline medium  It is determined to validate if globulin is
higher that albumin.
Dye Protein bonds to For research use
dye and causes a  If globulin is greater than albumin it is
binding
spectral shift in the known as inverted A/G seen in cirrhosis,
absorbance multiple myeloma and Waldenstroms
maximum of the dye macroglobulinemia.

Refence value: 1.3-3:1

Albumin

 is synthesized in the liver

 It makes about 60% of the total protein in the
blood
Functions
a) Nourishes tissues
b) Transports hormones, vitamins, drugs and
substances like calcium throughout the body.
Prothrombin Time (Vitamin K Response
c) It keeps fluid from leaking out of the blood Test)
vessels
Measures the Extrinsic and Common
od
Principle Pathway of coagulation.

 It is used to monitor oral anticoagulant therapy; this can

1. Salt Precipitation Globulins are Labor intensive
detect deficiencies of prothrombin, fibrinogen, Factors V,
precipitated in
high salt concs. VII and X.
2. Dye Binding Albumin binds to  It differentiates intrahepatic disorder (prolonged protime)
- Methyl orange dye and causes
- HABA (2,4’- shift in absorption. from extrahepatic obstructive liver disease (normal).
hydroxyazobenzene-
  Prolonged protime despite Vit K administration Test Method
indicate loss of hepatic capacity to synthesize the Principle: Van den Berg Reaction is
proteins. (intramuscular;10 mg daily for 1 to 3 Diazotization of Bilirubin to produce azobilirubin.
days) A. Evelyn-Malloy Method
 Acute viral or toxic hepatitis signifies massive Coupling accelerator: Methanol
cellular damage. Diazo Reagents:
 PT reagent: thromboplastin or tissue Diazo A= 0.1 % Sulfanilic Acid + HCL
thromboplastin Diazo B= 0.5 % Sodium Nitrite
 Principle : When mixed with citrated PPP the PT Diazo Blank= 1.5% HCL
reagent triggers fibrin polymerization by Final Reaction: pink to purple azobilirubin
activating plasma factor VII thereby activating the *Measured at 560 nm
Extrinsic pathway of coagulation. B. Jendrassik and Grof Method
 Reference Interval : 10 – 12 seconds - It is most commonly used
 PT is particularly sensitive to liver disease which -More sensitive than Evelen-Malloy
causes factor VII to become rapidly diminished. method
 To distinguish between Vit K deficiency and liver - Coupling accelerator : Caffeine
disease, the laboratory determines Factors V and Sodium Benzoate
VII levels. - Buffer : Sodium Acetate
-Ascorbic acid- terminates the initial
Bilirubin reaction and destroys excess diazo
rgt.
 The end product of hemoglobin metabolism.
- Final reaction : pink to blue azobilirubin
 Principal pigment of the bile
Clinical Significance
 200-300 of Bilirubin is Produced per day
Jaundice
 Almost all of the bilirubin formed is eliminated in
a) Also called icterus or
the feces and only a small amount in urine
hyperbilirubinemia
 Healthy adult has low levels of Total Bilirubin b) Characterized by yellow discoloration
 Reference Range: of the skin, sclerae and mucus
 Conjugated Bilirubin : 0-0.2 mg/dL membranes
0-3 umol/L Classification of Jaundice
 Unconjugated Bilirubin : 0.2-0.8 mg/dL 1. Pre-hepatic/ Hemolytic Jaundice –
3-14 umol/L elevated Indirect Bilirubin
 Total Bilirubin : 0.2-1.0 mg/ dL 2. Post-hepatic/ Destructive Jaundice-
3-17 umol/L elevated Direct Bilirubin
3. Hepatocellualr Combined Jaundice-
Elevated direct and indirect bilirubin

Derangements of Bilirubin Metabolism

1. Gilbert’s Syndrome – Bilirubin

Transport deficit; elevated B1 (<3
mg/dL) Young adults 20-30 yrs old

2. Criggler Najjar syndrome- Conjugation

deficit; Infants; Elevated B1

3. Dubin Johnsons syndrome- Excretion

Specimen Collection and Storage deficit; elevated B2 and total Bilirubin
A Fasting Sample is preferred as the
presence of Lipemia will increase measured 4. Lucey Driscoll Syndrome- Elevated B1
Bilirubin Conc.
Bilirubin is very sensitive and is destroyed by light
If serumor plasma is separated from the cells and
stored in the dark it is stable for 2 days at room
temp. And 1 week at 4 degree C.