Enzymes is diagnosis Flashcards
What is the IU?
The amount of activity that will convert 1 micromole of a substrate per minute under stander conditions.
What are GPT and GOT values used for?
A high level of these enzymes can indicate liver damage.
GPT is an indication of muscle damage, it is more specific to liver damage. An elevation can occur during intense exercise. GOT can originate from red blood cells. It can indicate myocardial infarction and muscle damage. The total transaminase count can be used to deduce whether there is liver damage. The normal value for each enzyme is between 5-50 IU/L. Very high values is often as a result of paracetamol poisoning or severe liver failure.
What can elevated albumin show? What can elevated alkaline phosphatase show?
Albumin: Loss of secretory function fo the liver of problems with the kidney. Normal levels are between 3 - 5 g/dL.
Elevated ALP: This can indicate large bile duct obstruction. However this also occurs in Paget’s disease (bond disease), in growing children or the third trimester of pregnancy.
What is INR? What can it show?
Prothrombin time - it is used to show how long it takes a person to clot blood. An increased INR can show a loss of liver function as it may be unable to secrete blood clotting factors. This INR can also be used to see if an individual needs more or less Warfarin or Vitamin K.
What is an Isoenzyme? Use Lactate dehydrogenase as an example.
Isoenzymes are enzymes that differ in amino acid sequence but catalyse the same chemical reaction.LDH turns pyruvate into lactate in the muscles - in the liver it does the opposite. It is a tetramer of subunits. It has 2 subunits ‘H’ and ‘M’ subunits. There are 5 different combinations. H4 is found in the heart and is elevated in serum after an acute myocardial infarction. A high LDH1 (H4) can also be caused by other conditions and so other tests need to be done to ensure there was a heart attack.
Use cyclo-oxygenases as an example of isoenzymes.
COX-1 and COX-2 are isoenzymes. These are is a membrane-bound enzyme responsible for the oxidation of arachidonic acid to prostaglandins.
Use creatine kinase as an example of isoenzymes.
Creatine Kinase is made up of 2 polypeptide chains. It is made up of a combination of M and B subunits. Different combinations of these subunits are found in different tissues. The brain has mostly the BB isoform and skeletal muscle had mostly MM. MB is found predominantly in the myocardium and increases with an acute myocardial infarction. If BB is found in the blood, it can indicate neurological disorders or cancers.
What are the markers of cardiac injury?
- Myoglobin (spikes early)
- Cardiac troponin
- Lactate dehydrogenase
- Creatine Kinase (however used mostly in crash injuries to establish the extent of muscle damage)
How is paracetamol poisoning treated?
Treatment is needed within 12 hours or else the liver may be so damaged, a transplant is needed. It is then treated with N-acteylcysteine (sometimes in combination with methionine) but a precise dose is needed. Blood is drawn a bacterial enzyme is used to identify the concentration of paracetamol.
How is blood glucose concentration measured?
normal levels are 4-5 mmol/l (0.72 - 0.99 mg/ml). Hypoglycaemia can lead to coma and can be fatal. Hyperglycaemia is in comparison not acutely dangerous but in the ling term can damage micro-vascular regions for example those in the eyes. Blood glucose level can be detected using test strips or an electronic output.
