Mechanism of Abnormal Enzyme Function.pdf

Mechanisms Responsible for Abnormal Enzyme Levels Introduction When cells are exposed to injury or stress, the structural integrity of the cell membrane can become compromised. This disruption leads to the release of intracellular components, including enzymes, into the extracellular space an...

Mechanisms Responsible for Abnormal Enzyme Levels Introduction When cells are exposed to injury or stress, the structural integrity of the cell membrane can become compromised. This disruption leads to the release of intracellular components, including enzymes, into the extracellular space and ultimately into the bloodstream. Under normal physiological conditions, the cell membrane serves as a selective barrier that tightly regulates the movement of substances in and out of the cell. during cellular damage caused by physical trauma, ischemia, toxins, or inflammation, the membrane's permeability increases. As a result, enzymes that are normally confined within the cytoplasm or organelles, such as lysosomes and mitochondria, leak out. This leakage of enzymes is a key indicator of cellular injury and is often measured in clinical settings to assess tissue damage, as seen in conditions like liver injury, myocardial infarction, and pancreatitis. The degree of enzyme release is often proportional to the extent of cellular damage, making it a useful biomarker for diagnosing and monitoring various pathological conditions. Major cause or mechanisms responsible for abnormal enzyme levels mentioned below- 1. Cellular Injury or Damage Tissue Breakdown: When cells are damaged, enzymes leak out into the bloodstream. For example, elevated liver enzymes (ALT, AST) in blood often indicate hepatocellular injury. Necrosis: Severe cellular injury or death releases large amounts of enzymes into circulation. Examples include cardiac enzymes (CK-MB, troponin) after myocardial infarction. 2. Increased Synthesis of Enzymes Induction of Enzymes: Some conditions stimulate increased production of enzymes. For instance, in alcoholism or drug abuse, cytochrome P450 enzymes are upregulated to detoxify the increased load of xenobiotics. Hyperplasia of Enzyme-Producing Cells: In some diseases, such as cancer, increased proliferation of cells can lead to the overproduction of enzymes (e.g., alkaline phosphatase in bone metastases). 3. Reduced Clearance or Excretion Renal or Hepatic Dysfunction: When the organs responsible for clearing enzymes from the bloodstream, such as the liver or kidneys, are impaired, enzyme levels may remain elevated. For example, amylase and lipase levels are elevated in pancreatitis due to reduced renal clearance. Biliary Obstruction: In cases of bile duct obstruction, enzymes like alkaline phosphatase and gamma-Glutamyl transferase (GGT) can build up. 4. Increased Permeability of Cell Membranes Membrane Damage: Conditions that cause alterations in membrane integrity, like hypoxia or ischemia, lead to the leakage of intracellular enzymes into the bloodstream. For example, lactic dehydrogenase (LDH) is released in many types of cell damage. 5. Genetic or Inherited Conditions Enzyme Deficiency or Malfunction: Some genetic disorders lead to enzyme malfunction or deficiency, leading to abnormal levels of enzymes. For example, glucose-6-phosphate dehydrogenase (G6PD) deficiency can lead to abnormal enzyme activity and related symptoms.  Congenital Disorders: In some metabolic disorders, abnormal enzymes can accumulate or fail to function, leading to altered enzyme levels (e.g., in lysosomal storage diseases). 6. Increased Turnover of Tissue Rapid Cell Proliferation or Destruction: Conditions like cancer or acute tissue injury can result in the rapid turnover of cells, leading to the release of enzymes into the bloodstream. 7. Infections and Inflammatory Conditions Inflammatory Response: Infections and inflammatory diseases can stimulate cells to release enzymes, either due to direct cellular damage or immune-mediated processes. For instance, elevated liver enzymes may be seen in viral hepatitis.