How? *The measurement of the serum levels of numerous enzymes has been shown to be of diagnostic significance. *This is because the presence of these enzymes in the serum indicates that tissue or cellular damage has occurred resulting in the release of intracellular components into the blood &this increases the level of certain enzymes in blood according to the damaged organWhat are the enzymes most used in the diagnosis of certain diseases?
Lactate dehydrogenase(LDH) Lactic acid Pyruvic acid NAD NADH+H*LDH is a tetramer(consists of 4 protomers)*the protomers are 2 types:- 1-H(after heart) 2-M(after muscle) so LDH have 5 isoenzymes:-
LDH 1 – Found in heart and red-blood cells and is 17% – 27% of thenormal serum total*It is formed of HHHH.It increases in myocardial infarctionLDH 2 – Found in heart and red-blood cells and is 27% – 37% of the normal serum total*It is formed of HHHM.It increases in myocardial infarctionLDH 3 – Found in a variety of organs and is 18% – 25% of the normal serum total*It is formed of HHMM.It increases in leukaemiaLDH 4 – Found in a variety of organs and is 3% – 8% of the normal serum total*It is formed of HMMM.It increases in viral hepatitisLDH 5 – Found in liver and skeletal muscle and is 0% – 5% of thenormal serum total*It is formed of MMMM.It increases in viral hepatitis
Creatine kinase (CK)Creatine Ceatine phosphate ATP ADP*CK is a dimmer (consists of 2 protomers)*the protomers are 2 types:1-B (after brain)2-M (after muscle)*so CK has 3 isoenzymes:-
.CPK1 (CPK-BB) is the characteristic isoenzyme in brain and isin significant amounts in smooth muscle and is 0% of the normalserum total.**It increases in brain tumors..CPK2 (CPK-MB) accounts for about 35% of the CPK activity incardiac muscle , but less than 5% in skeletal muscle and is 0% ofthe normal serum total.**It increases in heart diseases..CPK3 (CPK-MM) is the predominant isoenzyme in muscle andis 100% of the normal serum total.**It increases in skeletal muscle diseases.
Alanine transminase(ALT)*It is also called serum glutamic pyruvic transminase(SGPT)*It catalyzes transfer of amino group (NH2) fromamino acid (alanine) to a-keto acid producting a newamino acid & a new keto acid*ALT is particularly diagnostic of liver involvement as thisenzyme is found predominantly in hepatocytes.*It increases in liver & heart diseases.
Aspartate transminase(AST) Glutamic oxalacetic transminase(SGOT)*It is also called aspartate glutamic oxalacetictransminase(SGOT)*It increases in liver & heart diseases *When assaying for both ALT and AST the ratio of the level of these twoenzymes can also be diagnostic. Normally in liver disease or damage that is notof viral origin the ratio of ALT/AST is less than1.with viral hepatitis the ALT/ASTratio will be greater than1.*The level of AST elevation in the serum is directly proportional to the numberof cells involved as well as on the time following injury that the AST assay wasperformed. Following injury, levels of AST rise within 8 hours and peak 24–36hours later. Within 3–7 days the level of AST should return to pre-injury levelsunless further injury occurs.* Although measurement of AST is not, in and of itself, diagnostic formyocardial infarction, taken together with LDH and CK measurements the levelof AST is useful for timing of the infarct
Alkaline phosphatase Acid phosphatase**It is an enzyme which transport **is found in the prostate, redphosphate groups across cell blood cells, small amountsmembranes of organs. are found in bone, liver,**It is found in the spleen and pancreas.osteoblasts,bile canali ,smallintestinal epithelium and **The assay of serum acidproximal tubule. phosphatase is mostly used**Increases mainly in bone to detect prostaticdiseases such as Osteogenic carcinoma and to monitorsarcoma ,liver & bilary tract the treatment.diseases andhyperparathyroidism**Amylase and lypase enzymes increases in diseases of the pancreas asacute pancreatitis