LIVER FUNCTION TESTS Flashcards by V S

Liver is composed of 2 types of cells:

Hepatocytes
Kupffer Cells (Phagocytic)

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To abolish liver tissue function, more than ___ of the liver must be destroyed

80%

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Liver secretes plasma proteins, carbohydrates, lipids, lipoproteins, clotting factors, ketone bodies and enzymes

12g of albumin produced daily

Synthetic Function

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Involved in metabolism of bilirubin

200g - 300g of bilirubin produced daily

Conjugation Function

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Liver serves to protecy the body from potentially injurous substances absorbed from intestinal tract and toxic by-products of metabolism
Ammonia is converted to urea in liver

Detoxification and Drug metabolism

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Excretion of bile involves the elimination of bile acids or salts, pigments, cholesterol

Excretory and Secretory Function

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Storage site for all fat-soluble and water-soluble vitamins
Storage depot for glycogen

Storage Function

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Important for assessing nutritional status and presence of severe disease involving liver, kidney and bone marrow

Total Protein

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Transudates have a TP of

(<)3.0 g/dL

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Exudates have a TP of:

(> 3.0 g/dL)

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Total Protein is usually performed in serum, which has no __ and no ____

Fibrinogen
and Anticoagulant

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Reference Method of TP

6.5-8.3 g/dL

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Reference method but not routinely use
Based on measurement of the nitrogen content of protein
Serum treated with tungstic acid, forming protein-free filtrate

Kjedahl Method

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Nitrogen content of proteins

15.1% to 16.8%

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Reagent of Kjedahl Method

H2SO4
Sulfuric Acid

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End product of Kjedahl Method

Ammonia

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Most widely used method
Extensively used in clinical laboratories
Requires at least 2 peptide bonds and an alkaline medium to measure total protein

Biuret Method

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Cupric ions complex the groups involved in the peptide bond forming a violet-colored chelate is ___ to the number of peptide bonds present and reflects the TP level at 545 nm

Proportional

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Reagents of Biuret Method:

Alkaline Copper Sulfate
Rochelle Salt (NaK Tartrate)
NaOH & Potassium Iodide

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Highest Analytical Sensitivity
Oxidation of phenolic compounds such as tyrosine, tryptophan and histidine to give a deep blue color

Folin-Ciocalteu (Lowry) Method

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Main reagent of Folin-Ciocalteu

Phosphotungstic-Molybdic Acid
Phenol Reagent

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Color enhancer of Folin-Ciocalteu Method

Biuret reagent

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Absorbance of proteins at 210 nm is due to absorbance of peptide bonds at specific wavelength
Proteins absorb light at 280 nm and at 210 nm

Ultraviolet Absorption Method

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Migration of charged particles in an electric field

Serum Protein Electrophoresis

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Fastest band Most Anodal Protein

Albumin

2nd Fastest band Includes: > Glycoproteins > AAT > AAG (A1- Acid glycoprotein) > TBG Increases as a non specific response to inflammation

Alpha-1 Globulin

3rd Fastest band Includes: 1. Haptoglobin 2. AMG (a2-Macroglobulin) 3. Ceruloplasmin

Alpha-2 Globulin

4th band Includes: 1. Transferrin 2. Beta-lipoprotein 3. Hemopexin 4. Complement C3 and C4

Beta Globulin

5th band Slowest band Includes: Immunoglobulin CRP

Gamma-globulin

Gamma Spike

Multiple Myeloma

Beta-Gamma bridging

Hepatic Cirrhosis

A2-Globulin band spike

Nephrotic Syndrome

A1-Globulin Flat curve

Juvenile Cirrhosis or AAT deficiency

Spikes of a1, a2, and B globulin bands

Inflammation

Presence of this protein causes "Blip" in late alpha-2 or early beta zone

Free Hemoglobin

Presence of small spikes in beta region is due to:

Iron Deficiency Anema Transferrin

Alternative test to chemical analysis of serum total proteins Based on measurement of refractive index of solutes in serum

Refractometry

Utilize Sulfosalicylic Acid or Trichloroacetic acid Measurement depends on formation of a uniform fine ppt which scatters incident light in suspension (nephelometry) or block light (turbidimetry)

Turbidimetric and Nephelometric Method

Globulins can be separated from albumin by salting-out procedures using sodium salts Globulin is insoluble in water but not in dilute salt solution

Salt Fractionation

1. Malignancy 2. Multiple Myeloma 3. Waldenstrom's Macroglobulinemia

Increased TP

1. Hepatic Cirrhosis 2. Glomerulonephritis 3. Nephrotic Syndrome 4. Starvation

Decreased Total Protein

Differentiates intrahepatic disorder (prolonged protime) from extrahepatic obstructive liver disease (normal protime)

Prothrombin Time Vitamin K Response Test

Concentration of this protein is inversely proportional to the severity of the liver disease

Albumin

Low total protein + Low albumin =

Hepatic Cirrhosis (Gradual loss) Nephrotic Syndrome (Abrupt loss)

Most commonly used dye for measurement

Bromcresol Green (BCG)

Most Specific Dye used for measurement

Bromcresol Purple

1. Severe Dehydration 2. Prolonged tourniquet application (Artifactual Hyperalbuminemia)

Hyperalbuminemia

1. Reduced Synthesis * Chronic Liver Disease * Malabsorption Syndrome * Malnutrition and Muscle Wasting Disease 2. Increased Loss * Nephrotic Syndrome (Inc Albumin excretion) * Massive burns * Protein-losing enteropathy * Orthostatic Albuminuria 3. Increased Catabolism * Massive burns * Widespread malignancy * Thyrotoxicosis

Hypoalbuminemia

Hereditary absence of albumin or inability to synthesize albumin

Analbuminemia

Presence of 2 albumin bands instead of a single band in electrophoresis Presence of albumin with unusual molecular characteristics in blood

Bisalbuminemia

Determine to validate if globulin is higher than albumin

Albumin/Globulin Ratio

If globulin is greater than albumin is known as **inverted A/G ratio** and seen in:

1. Cirrhosis 2. Multiple Myeloma 3. Waldenstrom's Macroglobulinemia

Reference Value of A/G ratio

1.3 - 3.1

End product of hemoglobin metabolism and the principla pigment in bile Formed from destruction of heme-containing proteins such as myoglobin, catalase and cytochrome oxidase

Bilirubin

Enzyme that is needed to conjugate Uncojugated bilirubin in the Liver

Uridine Diphosphate Glucoronyl Transferase UDPGT

Unconjugated bilirubin binds to ___ to be transported Liver

Albumin

Uncojugated Bilirubin is increased in:

Pre-hepatic bilirubin

Uncojugated Bilirubin is increased in:

Pre-hepatic bilirubin

Conjugated bilirubin is increased:

1. Post-hepatic bilirubin 2. Hepatic bilirubin 3. Obstructive and Regurgitative bilirubin

Reference Value of Conjugated Bilirubin

0-0.2 mg/dL

Reference Value of Uncojugated bilirubin

0.2 - 0.8 mg/dL

Reference Value for Total bilirubin

0.2 - 1.0 mg/dL

Conjugated bilirubin tightly bound to albumin Formed due to prolonged elevation of conjugated bilirubin in biliary obstruction Reacts with Diazo reagent

Delta Bilirubin

Computed Delta bilirubin formula:

TB - DB + IB = Delta Bilirubin

Reference Value of Delta Bilirubin

(<) 0.2 mg/dL

Also called Icterus or Hyperbilirubinemia Yellow discoloration of the skin, sclera and mucus membranes Bilirubin levels > 2mg/dL

Jaundice

Cause: Too much destruction of RBC Bilirubin Assay: Elevated B1, & Urobilinogen

Pre-hepatic Jaundice

Cause: Failure of bile to flow to the intestine or impaired bilirubin excretion Assay: Elevated B2

Post-Hepatic Jaundice

Cause: Hepatocyte injury caused by viruses, alcohol and parasites ASsay: Elevated B1, and B2, Urobilinogen & (+) Urine bilirubin

Hepatocellular Combined Jaundice

Characterized by impaired cellular uptake of bilirubin Lab: Elevated B1

Gilbert's Syndrome | Bilirubin Transport Deficity

Characterized by impaired cellular uptake of bilirubin Lab: Elevated B1 Bilirubin Transport Deficit

Gilbert's Syndrome | Bilirubin Transport Deficit

Infants are treated by phototherapy Lab: Elevated B1 Conjugation Deficit

Crigler-Najjar Syndrome

Deficiency of UDPGT Absence of B2 production (+) Kernicterus; Bile Colorless

Type 1 Crigler-Najjar Syndrome

Partial deficiency of UDPGT Decreased B2

Type 2 Crigler-Najjar Syndrome

Defective excretion of conjugated bilirubin into the canaliculi, caused by hepatocyte membrane defect Intense dark pigmentation of the liver (accumulation of lipofuschin pigment) Elevated B2 and Total Bilirubin Bilirubin Excretion Defect

Dubin-Johnson Syndrome & Rotor Syndrome

Familial form of unconjugated hyperbilirubinemia due to circulating inhibirot of bilirubin Elevated B1

Lucey-Driscoll Syndrome

What bilirubin can cross the blood-barrier and lead to kernicterus

Unbound Bilirubin Free Bilirubin

Most common cause of hyperbilirubinemia in adults

Cholelithiasis (Gall stones)

Van den Berg Reaction is diazotization of bilirubin to produce what:

Azobilirubin

Accelator: Methanol Diazo Reagents: Diazo A = 0.1% Sulfanilic Acid + HCl Diazo B = 0.5% Sodium Nitrite Diazo Blank = 1.5% HCl Final: Pink to purple Azobilirubin

Evelyn and Malloy Method

Most commonly used method More sensitice than Evelyn & Malloy method Not affected by Hemoglobin up to 750 mg/dL & pH changes Main reagent: Diazo Reagent Coupling Accelerator: Caffeine Sodium Benzoate Final: Pink to Blue azobilirubin

Jendrassik & Grof Method

Solution that provides an alkaline pH

Alkaline tartrate solution

1. Gilbert's Syndrome 2. Criggler-Najjar Syndrome 3. Hemolytic Anemia 4. Hepatocellular disease 5. Lucey Driscoll 6. G-6-PD deficiency

Increased B1 Uncojugated Bilirubin

1. Biliary Obstruction 2. Pancreatic cancer 3. Dubin-Johnson Syndrome (Bilirubin Excretion Deficit) 4. Alcoholic & Viral hepatits 5. Biliary Atresia 6. Hepatocellular disease

Increased B2 Conjugated Bilirubin

Test for hepatocellular function and potency of bile duct Rarely used

Bromsulfonthalein (BSP) Dye Excretion Test

Double Collection Method Dose: 2mg/BW of patient Collect: after 5 minutes & 30 minutes

Rosenthal White

Single Collection Method Dose: 5kg/BW Collect: after 45 minutes

Mac Donald Method

Colorless end product of bilirubin metabolism that is oxidized by intestinal bacteria to the brown pigment, **urobilin**

Urobilinogen

Excreted in urine and feces, or reabsorbed into the portal blood & returned to liver

Urobilinogen

Absence of Urobilinogen in urine or stool denotes

Complete Biliary Obstruction

Method for Urobilinogen:

Ehrlich's Method p-dimethyl aminobenzaldehyde reagent

Reference Value: Urobilinogen

Urine: 0.1 - 1.0 Ehrlich units/2 hr Stool: 75 - 275 Ehrlich units/100g feces

Used to assess the extent of liver damage & differentiate hepatocellular from obstructive disease

Enzyme tests

Enzymes secreted by the liver:

Alkaline Phosphatase Aminotransferases 5' nucleotidase Gamma-Glutamyl Transferase OCT LAP Lactate Dehydrogenase

Arises from deamination of amino acids, through action of digestive & bacterial enzymes on proteins in intestinal tract Marker for Detoxification Liver normally removes most of this NPN and converts it to Urea and eliminated by kidneys

Ammonia

Reference Value of Ammonia

19 - 60 ug/dL

Increased levels of Ammonia

1. Cirrhosis 2. Hepatitis 3. Reye's Sydrome 4. Chronic Renal Disease 5. Acetaminophen poisoning

Nitrogen is converted to Ammonia by **Sulfuric Acid** in presence of Catalys (CuSO4, Mercury & Selenium)

Kjedahl Method Digestion Method

Ammonia + K2Hg2I2 ----Gum Ghatti---> NH2Hg2I2 End color: Yellow if N2 low to moderate End color: Orange if N2 high

Nesslerization Reaction

NH3 + Phenol + Hypochlorite ----Na Nitroprusside---> Indophenol Blue

Berthelot Reaction

NH3 + a-ketoglutarate + NADPH ---Glutamate Dehydrogenase----> Glutamate + NADP

Glutamate Dehydrogenase Method