Summary of Enzymes and Their Clinical Significance PDF

SUMMARY OF ENZYMES AND THEIR CLINICAL SIGNIFICANCE ACCORDING TO DEAN RODRIGUEZ: 1.Alkaline Phosphate/Alkaline Orthophosphoric Monoester Phosphohydrolase  Bone isoenzyme increases due to osteoblastic activity and is normally elevated in children during periods of growth and in ad...

SUMMARY OF ENZYMES AND THEIR CLINICAL SIGNIFICANCE ACCORDING TO DEAN RODRIGUEZ: 1.Alkaline Phosphate/Alkaline Orthophosphoric Monoester Phosphohydrolase  Bone isoenzyme increases due to osteoblastic activity and is normally elevated in children during periods of growth and in adults older than age 50 years (geriatric).  The presence of intestinal ALP isoenzyme in serum depends on the blood group (secretor gene and H substance) of the individual. B or O blood group increases intestinal ALP after consumption of a fatty meal.  For bone disorders, highest elevations occur in Paget's disease (osteitis deformans). Bone ALP isoform, B1x, was detected in the serum of dialysis patients. Carcinoplacental ALP: 1. Regan ALP-is found in lung, breast, ovarian and gynecological cancers; bone ALP co-migrator; most heat stable ALP (65°C for 30 minutes); inhibited by phenylalanine reagent 2. Nagao ALP-found in adenocarcinoma of the pancreas and bile duct, pleural cancer; variant of Regan ALP, inhibited by L-leucine and phenylalanine. Methods: 1. Electrophoresis Liver and bone ALPs are the most anodal isoenzymes; intestinal ALP is the least anodal Use of neuraminidase and wheat germ lectin improves separation of bone and liver ALPS. Liver-Bone-Placental-Intestinal 2. Heat Fractionation/Stability Test  It is performed at 56°C for 10-15 minutes.  Placental ALP is the most heat stable; bone ALP is the most heat labile. Decreasing order of ALP heat stability: placental, intestinal, liver and bone 3. Chemical Inhibition Test  This method uses different concentrations of phenylalanine, synthetic urea and levamisole solutions. Placental and intestinal ALPs are inhibited by phenylalanine reagent and 3M urea inhibits bone  ALP. Levamisole reagent inhibits liver and bone ALP. 4. Bowers and Mc Comb (Szasz modification) Is considered as the most specific method. Notes to Remember:  Decreased ALP is seen in zinc deficiency. Increased ALP 1. Osteitis deformans 2. Obstructive jaundice 3. Osteomalacia 4. Rickets 5. Osteoblastic bone tumors-osteosarcoma 6. Sprue 7. Hyperparathyroidism 8. Hepatitis and cirrhosis (slight increased) 2. Acid Phosphatase/ Acid Orthophosphoric Monoester Phosphohydrolase  It catalyzes the same reaction made by ALP, except that it is active at pH 5.0.  ACP activity >50 IU/L indicates the presence of seminal fluid in the sample. Tissue sources: prostate (major source)  Diagnostic Significance:  For detection of prostatic adenocarcinoma.  It also useful in forensic clinical chemistry, in the investigation of rape cases Notes to Remember   Thymolphthalein monophosphate is the specific substrate; substrate of choice for quantitative  endpoint reaction. Serum sample must be free from hemolysis. Tartrate-resistant acid phosphatase (TRAP) is present in certain chronic leukemias and some lymphomas, most notably in hairy cell leukemia. Increased ACP (with Metastatic Bone Involvement) 1. Prostatic carcinoma 2. Breast, lung and thyroid carcinoma 3. Gaucher's disease 4. Niemann Pick Disease TRANSFERASES/TRANSAMINASES A. Aspartate Aminotransferase (AST)  It has 2 isoenzyme fractions, cytoplasm and mitochondrial ASTs-the cytoplasmic isoenzyme is the predominant form in serum. Major tissue source: cardiac tissue, liver and skeletal muscle  Diagnostic Significance:  In the evaluation of myocardial infarction, hepatocellular disorders and skeletal muscle involvement.   In acute myocardial infarction (AMI), AST levels begin to rise 6-8 hours, peak at 24 hours and normalize within 5 days Method: Karmen Method pH 7.5; 340nm  It uses malate dehydrogenase (MD) and monitors the change in absorbance at 340 nm. AST B. Alanine Aminotransferase (ALT)  It has enzymatic activity similar to AST.  The highest concentration is in the liver; more liver-specific than AST. Major tissue source: liver  Diagnostic Significance:  It is significant in the evaluation of hepatic disorders markedly increased concentration in acute inflammatory conditions than AST.  ALT measurement is a more sensitive and specific screening test for posttransfusion hepatitis or occupational toxic exposure compared to AST. Method:  Aminotransferases require pyridoxal phosphate (vitamin B as coenzyme (prosthetic group).  Hemolysis should be avoided because it increases AST 10x.  Heparin may inhibit the activity of AST (but not all methods). Increased Transferases 1. Toxic hepatitis 2. Acute Myocardial Infarction - AST 3. Wolff-Parkinson White Syndrome 4. Trichinosis-AST 5. Chronic alcoholism 6. Dermatomyositis - AST 8. Reye's syndrome 9. Viral hepatitis hepatitis AST 10. Muscular Dystrophy-AST 11. Acute pancreatitis AST Notes to Remember  The highest elevations of transferase is seen in acute hepatitis.  Severe viral or toxic hepatitis may produce elevations of transferase up to 20x the normal limits.   In acute hepatitis, the De Ritis ratio (ALT:AST) is > 1.0.  Moderate elevation of transferase in chronic hepatitis, hepatic cancer and infectious mononucleosis. Slightly increased in hepatic cirrhosis, alcoholic hepatitis and obstructive jaundice.  ALT is slightly increased in obstructive jaundice but markedly increased in necrotic jaundice.  III. AMYLASE/ ALPHA-1-4 GLUCAN-4-GLUCOHYDROLASE (AMS)  It catalyzes the breakdown of starch and glycogen an important enzyme in the physiologic digestion of starch. It is the smallest enzyme in size (with a MW of 50,000 to 55,000 daltons)  It is the earliest pancreatic marker.  Isoenzymes: S-type (ptyalin) and P-type (amylopsin) both present in normal healthy sera  Methods: Substrate for all the methods: Starch 1. Saccharogenic  It is the classic reference method expressed in Somogyi units.  It measures the amount of reducing sugars produced by the hydrolysis of starch by the usual glucose methods. 2. Amyloclastic  It measures amylase activity by following the decreases in substrate concentration (degradation of starch). 3.Chromogenic  It measures amylase activity by the increase in color intensity of the soluble dye-substrate solution produced in the reaction. 4. Coupled-enzyme It measures amylase activity by a continuous-monitoring technique. Increased Serum Amylase 1. Acute pancreatitis 2. Ectopic pregnancy 3. Peptic ulcers 4. Alcoholism 5. Mumps-Parotitis IV. LIPASE (LPS)/TRIACYLGLYCEROL ACYLHYDROLASE  Plasma concentrations are normal in conditions of salivary gland involvement.  Major tissue source: Pancreas Methods: 1. Cherry Crandal (reference method) Principle: Hydrolysis of olive oil after incubation for 24 hours at 37°C and titration of fatty acids using NaOH. Substrate: 50% olive oil / Triplein (pure TAC) End product: Fatty acid 2. Tietz and Flereck 3. Peroxidase coupling most commonly used method; does not use 50% olive oil. V. LACTATE DEHYDROGENASE (LD)  Is a hydrogen-transfer enzyme that uses the coenzyme nicotinamide dinucleotide (NAD+), It is a tetrameric molecule containing four subunits of two possible forms (H and M). Diagnostic Significance:  Highest serum levels are seen in pernicious anemia and hemolytic disorders.  In AMI, LD levels begin to rise within 12-24 hours, peak levels within 48-72 hours and remains  elevated for 10-14 days.  Hepatic carcinoma and toxic hepatitis will have 10-fold increased.   Viral hepatitis and cirrhosis would give LD slightly increased values (2-3x URL).  LD-1> LD-2 also known as the "flipped pattern" is seen in myocardial infarction and hemolytic anemia, LD-5 is moderately increased in acute viral hepatitis and cirrhosis and markedly increased in hepatic carcinoma and toxic hepatitis. LD-6 represents the alcohol dehydrogenase enzyme; 6th band in electrophoresis; elevated in drug hepatoxicity and obstructive jaundice; it is responsible for the metabolic conversion of methanol and ethylene glycol to toxic compounds; present in patients with arteriosclerotic failure Methods 1. Wacker Method (forward/direct reaction) reaction is at pH 8.8 Is the most commonly used method 2. Wrobleuski La Due (reverse/indirect reaction)-reaction is at pH 7.2  Decreased values of LD are observed when samples are frozen (LD-S is cold-labile), therefore samples should be processed within 24 hours after collection and stored at 25°C. VI. CREATINE KINASE/ATP-CREATINE-N-PHOSPHOTRANSFERASE (CK)  It is a dimeric molecule with small molecular size, composed of a pair of two different monomers called M and B. It is found in small amounts throughout the body, but is found in high concentrations only in  muscle and brain, although CK from brain virtually never crosses the blood-brain barrier to reach plasma. CK-MB