Enzymology II • Myoglobin • Is a heme protein found in skeletal and cardiac muscle that has attracted considerable interest as an early marker of MI.
• When heart or skeletal muscle is injured, myoglobin is released into the blood. Elevated levels can be measured within 30 minutes after injury occurs, unlike troponin and creatine kinase which can take 3-4 hours.
• The range of normal results for the serum myoglobin test will vary slightly based on the laboratory completing the analysis. In most instances, the normal (or negative) range for the serum myoglobin test is 0 to 85 nanogram per milliliter (ng/mL). Normal results will allow your doctor to rule out a heart attack. • Abnormal (above 85 ng/mL) • Lactate Dehydrogenase
• • Present in almost all tissues • • ↑in disorders affecting many organs and systems • • Most often measured in myocardial infraction.
• Structure • 4 polypeptide chains either H (heart) or M (muscle)
• Five isoenzymes with different subunit combinations:
• LD1 LD2 LD3 LD4 LD5 (H4) (H3M) (2H2M) (HM3) (M4) • Cardiac Ms Lung Liver, Skeletal Ms • Time sequence of LD after myocardial infarction
• ↑ after 12-24 hours
• peak after 3-5 days
• ↓ to normal after 7-12 days
• Reference range < 250 U/L • Pancreatitis
• The pancreas has an endocrine function because it releases juices directly into the bloodstream, and it has an exocrine function because it releases juices into ducts.
• Enzymes, or digestive juices, are secreted by the pancreas into the small intestine. There, it continues breaking down food that has left the stomach.
• The pancreas also produces the hormone insulin and secretes it into the bloodstream, where it regulates the body's glucose or sugar level. Problems with insulin control can lead to diabetes.
• Other possible health problems include pancreatitis and pancreatic cancer. • Amylase, Lipase, and protease
• Amylase helps your body break down starches.
• Lipase helps your body digest fats.
• Also it produce protease for digestion of protein.
• The pancreas also produces many other enzymes.
• Inflammation of the pancreas, also called pancreatitis, commonly causes high levels of amylase and lipase in the bloodstream.
• Therefore, serum amylase and lipase are common tests obtained as biochemical markers for acute pancreatitis in patients presenting with abdominal pain. • Amylase and lipase tests are used to detect pancreatitis. The tests measure the amount of these enzymes circulating in the bloodstream. These enzymes are typically checked when you have symptoms of acute pancreatitis or another pancreatic disorder and your doctor wants to confirm the diagnosis.
• Symptoms of pancreatitis may include:
• severe abdominal pain • back pain • fever • nausea • vomiting • loss of appetite • What are normal levels of amylase and lipase?
Amylase levels Lipase levels 23-85 U/L Normal (some lab results go up to 0-160 U/L 140 U/L) Pancreatitis suspected > 200 U/L > 200 U/L • AMYLASE LIPASE
• ↑ starts at 4-12 h ↑ starts at 12-18 h • maximum 12-24 h maximum 24 h • Returns N 48-72 h Returns N 5-7 days
• Lipase has higher sensitivity than amylase in diagnosing acute pancreatitis.
• Serum lipase may be preferable because it remains normal in some nonpancreatic conditions that increase serum amylase including macroamylasemia, parotitis, and some carcinomas.
– Decreased serum calcium – Glycosuria (insulin secretion and ketoacidosis, and liver problem lipid and carbohydrate meytabolism). • The enzymatic cocktail contains lipase. Lipase normally digests triglycerides to free fatty acids beginning in the duodenum to facilitate micelle formation and fatty acid absorption. In the extravascular environment, damaged fat cells provide the trigs. These free fatty acids have an exposed carboxyl group. In their basic form there is a -1 charge shared between the two oxygens. Ca (+2) likes this and will bind it. In this way, the level of hypocalcemia can aid in determining the extent of the enzymatic damage and/or level of pancreatitis. • When the pancreas is damaged, these digestive enzymes can be found in the blood at higher levels than normal.
• Amylase or lipase results more than three times normal levels are likely to mean pancreatitis or damage to your pancreas.
• Serum amylase and lipase levels may be slightly elevated in chronic pancreatitis; high levels are found only during acute attacks of pancreatitis.
• However, in rare cases, there can be significant damage to the pancreas without abnormal amylase or lipase levels. In these cases, abdominal pain is the most common symptom.
• Early in the course of damage to the pancreas, amylase or lipase levels may be also be normal.
• Thank you