Clinical Enzymology Liver Transfera Flashcards
Liver transferases enzyme
AST, ALT, ALP, GGT
Alternative name for AST
Serum glutamic oxaloacetic transaminase (SGOT)
Substrate for AST
Aspartate
Reaction of AST
Exchange of amino group for oxaloacetate
Distribution of AST
Liver, Heart, Skeletal Muscle
Diagnostic use of AST
Increased in acute hepatocellular disorders, circulatory collapse, myocardial infarction
Moderate increase in AST
Muscular dystrophy, hepatic tumor, biliary obstruction, CHF, cardiac arrhythmia
Slight increase in AST
Cirrhosis, pericarditis, pulmonary infarction, cerebrovascular accident
Reference value for AST
5-35 IU/L or <36 IU/L
Isoenzymes of AST
Mitochondrial and cytoplasmic
Increase in cytoplasmic AST
Acute hepatocellular disorders (AHCDs)
Increase in mitochondrial AST
Hepatic failure, alcoholic liver disease (fulminant Hf)
Alternative name for ALT
Serum glutamic pyruvic transaminase (SGPT)
Reaction for ALT
Alanine is converted to pyruvate
Main purpose of ALT conversion
Amino acid metabolism and degradation (gluconeogenesis)
Diagnostic value of ALT in acute hepatocellular disorders
De Ritis ratio <1
Significance of De Ritis ratio in ALT
More specific, higher and sustained elevation (AST/ALT) - decreased <1
Comparison of half-life for AST and ALT
ALT has a longer half-life than AST
Distribution of ALT
Liver (more liver-specific)
Reference value for ALT
7-45 IU/L
Specimen consideration for AST and ALT
Avoid prolonged storage and hemolysis
Methods for AST and ALT
Reitman-Frankel and Karmen method
Reitman-Frankel method chemicals
2,4-dinitrophenylhydrazine and 0.4 N NaOH
Reitman-Frankel coenzyme/cofactor
Vitamin B6 (pyridoxine/pyridoxal phosphate)
Reitman-Frankel color product
Reddish brown at 505 nm
Reitman-Frankel color developer
2,4-DNPH
Method used for continuous monitoring of AST and ALT
Karmen method
pH buffer range for AST and ALT continues monitoring
7.3 to 7.8
Enzyme used for aspartate in AST method
Malate dehydrogenase
Enzyme used for alanine in ALT method
Lactate dehydrogenase
Product for AST in Karmen method
Malate and NAD (measured at decreased absorbance; 340 nm)
Product for ALT in Karmen method
Lactate and NAD (measured at decreased absorbance; 340 nm)
Activator for ALP
Magnesium (electrolyte)
Main isoenzymes of ALP
Intestine, Liver, Bone, Placenta
Small amounts of ALP found in
Kidney and Spleen
Liver isoenzyme of ALP
Hepatobiliary
Bone isoenzyme of ALP
Osteoblast
Diagnostic significance of pronounced ALP elevation
Bile duct obstruction, biliary cirrhosis, Paget’s disease, osteogenic sarcoma, hyperparathyroidism
Diagnostic significance of moderate ALP elevation
Granulomatous liver diseases, IM, metastatic bone tumors, rickets, osteomalacia
Diagnostic significance of slight ALP elevation
Viral hepatitis, cirrhosis, healing bone fractures, growing children, pregnancy
Reference range for ALP (Male)
53-128 IU/L
Reference range for ALP (Female)
49-98 IU/L
Reference range for ALP (Children)
54-369 IU
Methods to avoid in ALP determination
CK, LD, LP
Reference method for ALP determination
Bowers-McComb
Bowers-McComb substrate for ALP
p-nitrophenylphosphate
Product of Bowers-McComb method for ALP
p-nitrophenol (yellow)
Substrate in Bessy, Lowey, and Brock/Bowers-McComb method
p-nitrophenylphosphate
Measurable end product of Bessy, Lowey, and Brock/Bowers-McComb method
p-nitrophenol
Substrate in Bodansky, Sinowara, Jones, Reinhart method
B-glycerophosphate
Measurable endpoint in Shinowara method
Glycerol
Substrate in King Armstrong method
Phenylphosphate
Measurable end product in King Armstrong method
Phenol
Substrate in Huggins and Talalay method
Phenolphthalein diphosphate
Measurable end product in Huggins and Talalay method
Red phenolphthalein
Substrate in Moss method
Alpha-napthylphosphate
Measurable end product in Moss method
Alpha napthol
Substrate in Klein Babson and Reed method
Buffered phenolphthalein phosphate
Measurable end product in Klein Babson and Reed method
Phenolphthalein
Electrophoresis migration pattern of ALP isoenzymes
I, P, B, L (Intestine, Placenta, Bone, Liver)
Heat stability test for ALP isoenzymes
56°C for 10 minutes
Heat stability pattern of ALP isoenzymes
P, I, L, B (Placenta most heat stable)
Heat stability of Placental ALP
Resists heating at 65°C
Heat stability of Bone ALP
<20% activity at 30 minutes
Chemical inhibition by Phenylalanine
P, I (Placenta, Intestine, carcinoplacental)
Chemical inhibition by Levamisole
B, L (Bone, Liver)
Chemical inhibition by 3 molar urea
Bone
Intestinal ALP characteristic
Increased after fatty meal, found in B or O secretor individuals
Carcinoplacental abnormal isoenzyme
Regan
Where Regan isoenzyme is detected
Lung, breast, ovarian, colon, and gynecologic cancers
Carcinoplacental abnormal isoenzyme (Nagao)
Detected in carcinoma of pleural surfaces, pancreas, and bile duct
Carcinoplacental abnormal isoenzyme (Kasahara)
Associated with GI and hepatic tumors
Reference range for carcinoplacental isoenzymes
30-90 U/L
Function of GGT
Transfer gamma-glutamyl amino acid residues (glutathione)
Diagnostic use of GGT
Marker for hepatobiliary disorders, alcoholic liver disease, and microsomal induction by drugs and alcohol
Use of GGT in hepatobiliary obstructions
Identifies source of increased ALP
Popular use of GGT
Marker of chronic alcoholism
Reference range for GGT (Male)
6-55 IU/L
Reference range for GGT (Female)
5-38 IU/L
Pre-analytical consideration for GGT
Always use a sample blank
Effect of alcohol and drug abuse on GGT results
Increases GGT results
Stability of GGT in serum
Stable up to 1 week if refrigerated
Drugs that increase GGT
Warfarin, phenobarbital, phenytoin
Szasz method substrate for GGT
Gamma-glutamyl-p-nitroanilide + glycylglycine
Product of Szasz method for GGT
Gamma-glutamylglycylglycine + p-nitroanilide (yellow color)
Measuring wavelength for Szasz method
420 nm