LIVER FUNCTION TESTS
FUNCTIONS OF LIVER
1. SYNTHETIC FUNCTION
a. Synthesis of Plasma proteins (Albumin, Coagulation factors)
b. Synthesis of Cholesterol, Triacylglycerol & Lipoprotein synthesis
2. METABOLIC FUNCTION
a. Carbohydrates --- Glycolysis; Glycogenesis; Glycogenolysis, Gluconeogenesis ,TCA
b. Lipids --- Ketone Bodies, Fatty acid, Lp and Apoproteins
c. Proteins --- Protein catabolism to Aminoacids .
3. DETOXIFICATION
a. Endogenous -- Ammonia detoxified to Urea
b. Exogenous -- Drug metabolites-- water soluble, conjugate with GGG to be excreted in urine
4. EXCRETORY
a. Substances detoxified in the liver are excreted---Bilirubin & Bile Pigments
5. HOMEOSTASIS: Blood Glucose regulation
6. STORAGE FUNCTION: Vitamin A, D, K, B12
Bilirubin Metabolism
INDICATIONS FOR LFT
1. Jaundice
2. Suspected liver metastasis
3. Alcoholic liver disease
4. Any undiagnosed Chronic Illness
5. Annual check up of Diabetic patients
6. Coagulation disorders
7. Therapy with Statins to check Hepatotoxicity
CLASSIFICATION OF LFT
• Group I (Tests of Hepatic excretory function)
1. Serum: Bilirubin; Total, conjugated, and unconjugated
2. Urine: Bile pigments, bile salts and urobilinogen
3. Bromosulphathelien Test
• Group II: Liver enzyme panel ( Serum Enzymes)
1. Alanine aminotransferase (ALT) (Marker of liver injury)
2. Aspartate aminotransferase (AST) (Marker of liver injury)
3. Alkaline phosphatase (ALP) (Marker of cholestasis)
4. Gamma glutamyl transferase (GGT) (Marker of cholestasis)
• Group III: (Tests for synthetic function of liver) Plasma proteins
(Marker, chronic liver diseases)
1.Total proteins
2. Serum Albumin, Globulins.
3. Prothrombin .
• Group IV: (Tests for Metabolic function)
1.Galactose Tolerance test ( Galactose – Glycogen )
2. Antipyrine clearance
• Group V: ( Tests for Detoxification function )
1. Hippuric Acid synthesis ( Benzoic acid + Glycine )
Others
VandenBergh Reaction
CLASSIFICATION BASED ON CLINICAL MANIFESTATIONS
Group I: Markers of liver Dysfunction
1. Serum Bilirubin, Total, Conjugated
2. Urine: Bile pigments, Bile salts and UBG
3. Total Protein, Serum Albumin
4. Prothrombin time
Group II: Markers of Hepatocellular Injury
1. Alanine amino transferase (ALT)
2. Aspartate amino transferase (AST)
Group III: Markers of Cholestasis
1. Alkaline Phosphatase
2. Gamma Glutamyl transferase
CLINICAL MANIFESTATIONS OF LIVER DYSFUNCTION
1) Jaundice ( S.Bilirubin > 2mg% )
Increased Hemolysis
2) Portal Hypertension ( Portal circulation @5mmHg)
Portal Varices, Porto-systemic shunting, Hyperammonemia, HypoAlbuminemia , Low Central BP
3) Ascites ( Accumulation of Serous fluid into the Abdominal cavity)
Scarring of Liver
Increased Resistance to blood flow
HypoAlbuminemia-- ↓d Colloid Osmotic Pressure
Protein rich serous fluid leaks to Intraperitoneal space
↓d CBP-- ↓d Renal perfusion –Activation of Renin-Angiotensin system.
Sodium and Water retention--- Fluid escapes into Peritoneal cavity.
Tests--- SAAG or SA: AFA ,1.1= Ascites due to Portal Hypertension
PRE HEPATIC HEPATIC POST HEPATIC
UNCONUGATED CONJUGATED
BILIRUBIN BILIRUBIN
HEMOLYTIC OBSTRUCTIVE
JAUNDICE JAUNDICE
VANDENBERG’S TEST VANDENBERG’S
INDIRECT POSITIVE TEST-
DIRECT POSITIVE
BOTH UNCONJGATED &
CONJUGATED BILIRUBIN
HEPATOCELLULAR JAUNDICE
VANDENBERG’S TEST – BIPHASIC
LIVER FUNCTION TEST Panel
1) S.Total Bilirubin 0.2- -1.0 mg%
2) S.Direct Bilirubin 0.0 --0.3 mg%
3) S.Indirect Bilirubin 0.2-- 0.6 mg%
4) S.Total Proteins 6.0-- 8.0 g%
5) S. Albumin 3.5--5.0 g%
6) S.Globulin 2.5--3.5 g%
A/G ratio 1.2:1-2.5:1
7) S.AST 5 - 45 U/L
8) S.ALT 5 - 45 U/L
9) S.ALKP 65 –158 U/L
10) S.GGT 5 – 40 U/L
