Final answer:
Isoenzymes in the circulating blood are not a type of plasma protein, but rather different enzymes released into the blood when there is tissue damage. Analysis of these isoenzymes can help diagnose the location of the damage.
Step-by-step explanation:
Isoenzymes in the circulating blood are not a type of plasma protein normally present in the circulating blood. Instead, isoenzymes are different enzymes that perform the same function in different body parts. They are usually released into the blood when there is tissue damage, and their analysis can help diagnose the location of the damage.
For example, an elevated level of LDH5 isoenzyme indicates liver damage, while a high level of LDH1 isoenzyme is indicative of heart damage. CK₂ levels also increase in cases of heart damage.
These isoenzymes typically function within cells, but can be released into the blood when tissue damage occurs. For instance, the presence of elevated levels of certain isoenzymes can indicate specific organ damage, such as LDH5 suggesting liver damage or a high level of LDH1 isoenzyme signifying myocardial infarction (heart damage). Additionally, the analysis of blood serum for the levels of these specific isoenzymes is used to diagnose the location of the damage. The increase in the concentration of certain enzymes in the plasma can indicate disorders to the tissue where they are primarily located, such as the Bence Jones proteins in the case of multiple myeloma. It is important to note that not all isoenzymes are involved in inflammation; some are involved in normal physiological processes such as plasma proteins contributing to blood clotting and immunity.