Uzair MumtazFarah Shafiq

Liver is the principle organ for maintaining the body’s internal environment & of vital importance in intermediary metabolism, detoxification and the elimination of toxic substances.

Largest internal body organ

Largest gland

Largest organ apart from skin

Weighs about 1.5kg

Found in the upper abdominal cavity: extends from right upper quadrant to left upper quadrant of the abdomen

Attached to diaphragm by1. Falciform and coronary ligaments

2. Left and right triangular ligaments

Metabolic

function

Excretory

function

Synthetic

function

Storage

function

Detoxification

function

Functions Of Liver

Hepatocytes synthesize:

Plasma Proteins

Coagulation factors like Prothrombin,

factors II,V,IX,X,XI,XII and XIII

Primary bile acids

Lipoproteins VLDL, HDL

Serum Total protein

Serum albumin

Total proteins - Albumin = Globulin

Prothrombin time

Serum Cholesterol

Principle:

Biuret’s method: Photometric endpoint, colorimetric assay

Proteins(3P)+Alkaline Cu tartrate= Blue-Purple coloured substance.

Reference Range: 65-80 g/l

Interpretations:

Dehydration

Hypergammaglobulinaemia

Infection

Cirrhosis, Ascites,

Cardiac failure

Estimation of Serum Albumin:

Principle: Bromocresol-Green method

Albumin+ BCG → Green coloured compound

(citrate buffer)

Reference Range: 35-50 g/l

Interpretation: Used to asses chronicity and severity of liver disease.

↓ in Chronic liver disease.

PROTHROMBIN TIME:

Synthetic dysfunction

↑ in liver disease due to ↓ of clotting factors

Reference Range: 10-14 sec

Liver is the only organ that has the capacity to rid the body of heme waste products.

Major heme waste product is Bilirubin, principle pigment of bile derived from breakdown of RBCs.

Hepatocytes in liver are separated by sinusoidal spaces along walls known as Kupffer cells present for detoxifying function.

Serum bilirubin

Urine Bilirubin

Urine & faecal urobilinogen

Urine bile salts

Dye excretion tests

Catabolism of Heme

Estimated by Van den bergh reaction

Principle:

When diazotised sulfanilic acid reacts with bilirubin, it forms ‘azobilirubin’, a purple coloured product.

↑ Conjugated Bilirubin: gives colour immediately

→ Direct positive

↑ Unconjugated Bilirubin: Gives colour after

addition of methanol → Indirect positive

↑ Both conjugated and Unconjugated → Biphasic

Ehrlich’s test:

Principle:

Urobilinogen reacts with ƿ-dimethylamino-benzaldehyde in chloroform to form a pink coloured aldehyde complex.

Bile salts: Hay testPrinciple: Bile salts have property of lowering

surface tension.Hence when sulphur powder is sprinkled to urine containing bile salts, it sinks to bottom.

Bile pigments: Fouchet’s testPrinciple: Bile pigments adhere to the

precipitate of barium sulphate. On addition of fouchet’s reagent, FeClз in presence of trichloroacetic acid oxidizes yellow colour bilirubin to green colour biliverdin.

Allows important substances to reach systemic circulation and serve as a barrier to prevent toxic or harmful substances

Either bind with material to inactivate the compound or chemically modify it

Drug Metabolism: Detoxification of drugs by

1. Oxidation

2. Reduction

3. Hydrolysis

4. Hydroxylation

5. Carboxylation

6. Demethyaltion

HIPPURIC ACID TEST:

Principle: Hippuric is produced in the liver when benzoic acid combines with glycine.

Procedure:

6gm of sodium benzoate is given to the patient.

Urine is collected up to 4hrs.

Hippuric excreted in urine is estimated.

Normal: >4.5g of hippuric acid

Abnormal: <3g of hippuric acid

Alpha-fetoprotein – Hepatoma

Alpha 1- antitrypsin – Congenital deficiency, Ininflammation

Serum copper – Wilson’s disease

Serum Iron – Hepatocellular damage

METABOLISM OF CARBOHYDRATES:

Store glucose as glycogen

Degrade glycogen to glucose (Glycogenolysis)

Create glucose from non-sugar carbon substrates e.g. pyruvate (Gluconeogenesis)

METABOLISM OF LIPIDS & LIPOPROTEINS:

Gathering free fatty acids from diet to produce Acetyl-CoA

Greatest source of cholesterol in body

METABOLISM OF PROTEINS:

Synthesize all proteins except immunoglobulin's complement & adult hemoglobin

Transamination of amino acids to produce ammonium ions.

CARBOHYDRATE METABOLISM• Glucose tolerance test

Interpretation:Normal: 2h PG level less than 7.8 mmol/lIGT: between 7.8-11.1 mmol/lDM: greater than 11.1 mmol/l

LIPID METABOLISM• Serum cholesterol

Protein metabolism

• Serum Ammonia:Liver detoxicates ammonia to form urea Normal: 40-70µg /100ml

Congenital defect in urea cycle Ornithine transcarbamylase deficiency Liver cirrhosis Hepatic failure Acute & sub acute liver necrosis

Sample: Arterial Blood

LFTs help in diagnosis of liver disease to evaluate severity, monitor therapy and asses the prognosis.

ALANINE AMINO TRANSFERASE:

Highest in liver

Principle: Coupled enzyme technique with continuous UV monitoring of NADH disappearance

ɖ -oxoglutarate + L- Alanine→L-glutamate+ pyruvate

Pyruvate+ NADH + H⁺→Lactate+ NAD⁺

Calculations:

ALT U/l = 1746 ӿ ∆A (340nm/min)Reference range: Up to 42U/l

ASPARTATE AMINOTRANSFERASE

Principle:

Coupled enzyme technique with UV monitoring of NADH disappearance.

Reaction:2-oxoglutarate+ L-aspartate → L-glutamate+oxaloacetate

Oxaloacetate+NADH+H⁺ → L-Malate+ NAD⁺

Calculations:

AST U/l = 1746 ӿ ∆A (340nm/min)

Reference range: Up to 0-37 U/l

Sample: Serum heparinized, EDTA plasma stable for 1 week at 2-8ºC

Serum shouldn't be hemolysed

Interpretation:

Markers of Hepatocellular damage.

Raised in Acute Hepatitis

Cytoplasmic Damage:↑ALT

Mitochondrial damage:↑AST

Derived from Liver, osteoblasts and placenta

Principle:Alkaline phosphatase catalyses the hydolysis of p-nitropheylphosphatse in the presence of Mg ions at alkaline pH

4-PNPP + H₂O → ƿ-Nitrophenol + PO₄

ALP U/l = 2760 ӿ ∆A/min @ 405nm

Reference Range= Adults 65-306 U/lChildren 0-645 U/l

↑ in cholestatic liver disease

Marker of severe Alcoholic Liver disease. Extremely sensitive test Reference Range: 11-60 U/l

5 Nucleotidase

Hydrolysis of nucleoside 5’ phosphate esters. Increased in hepatobiliary diseases

Measurement of GGT & 5- Nucleotidase tends to parallel Alp levels in hepato-biliary diseases.

Yellow colour of conjunctiva, mucous membrane, and skin due to increased bilirubin level

Pre hepatic Jaundice: ↑metabolismIn Acute & chronic hemolytic anemia'sHepatic Jaundice: Intrinsic liver defect or diseaseDue to disorders of bilirubin metabolism & transport

defects. Crigler najjar syndrome Dubin-johnson syndrome Gilbert’s disease Physiologic jaundice(Newborn)Post hepatic jaundice: biliary obstructive diseasePhysical obstructions gall stones and tumors

Gilbert syndrome:

Benign autosomal recessive hereditary disorder

Due to mutation in gene UGT1A1

Crigler najjar syndrome:

Due to defect in gene involved in bilirubin conjugation.

Dubin Johnson syndrome:

Rare autosomal recessive inherited disorder

↑ in delta bilirubin

Rotor syndrome:

Similar to dubin johnson

↓ ligandin

Physiological jaundice of Newborn:

↓ glucoronyl transferase

Cholestasis is an hepatic disorder characterized by retention of conjugated bilirubin & ALP

Cholestasis may be either:

INTRAHEPATIC: Bile secretion from hepatocytes into canaliculi is impaired

EXTRAHEPATIC: Due to obstruction to the flow of bile through biliary tract

Inflammation in liver tissue

INFECTIOUS: viral, bacterial & fungal infections

NON-INFECTIOUS: Drugs, chemicals & toxins

Symptoms: Jaundice, dark urine, fatigue, nausea, vomiting & abdominal pain

Clinical condition in which scar tissue replaces normal

SIGNS & SYMPTOMS: fatigue, nausea, weight loss, jaundice, bleeding from GIT

COMMON CAUSES: Chronic Alcoholism, HBV,HCV,HDV

Inherited disorders: ɖ1-antitrypsin deficiency, Wilson disease, hemochromatosis

Albumin , Total

protein, Total

Cholesterol

Prothrombin time

Hepatitis B HBsAg HBeAg Anti-HBs Anti-HBc HBV DNA Hepatitis C Anti HCV HCV RNA Auto-immune hepatitis: ANA ASTHMA

It is indicated in patients in whom ALT & AST are persistently greater than two-fold elevation.