Prekallikrein is a so-called proenzyme in the body, a chemical with the capacity to become an active enzyme when it is cleaved. This particular proenzyme turns into kallikrein, an active enzyme involved in the clotting process and the regulation of blood pressure. In rare cases, people can have a prekallikrein deficiency where not enough of this compound is produced. This can sometimes lead to health problems, as well as irregularities in the blood chemistry.
Prekallikrein is activated by factor XII, a blood protein. When it is cleaved by this protein into kallikrein, the active enzyme plays a role in mediating clotting processes and controlling the level of the blood pressure. The body will break down the components for elimination and recycling once the enzyme has been used, ensuring a steady supply of raw materials for making more prekallikrein, as well as other proenzymes and active enzymes.
This proenzyme is also known as Fletcher factor, named for a notable family with prekallikrein deficiencies studied in the United States. People deficient in prekallikrein can experience clotting abnormalities, such as developing blood clots, and may also bleed freely from the mucus membranes. The risk of pregnancy loss can also be increased, depending on the nature of the deficiency. As is common with genetic conditions, the severity of a deficiency can vary, as people inherit differing snippets of genetic material. People with blood disorders like sickle cell anemia are more likely to have low levels of prekallikrein in their bodies.
The kallikrein generated when this proenzyme is cleaved plays a role in the kinin system, a complex cascading process related to blood coagulation. Kallikreins are capable of breaking kinins away from kininogens, and can also separate plasma from plasminogens. The precise role of this enzyme in the body continues to be a topic of study, and kallikreins have been identified in varying concentrations in many areas of the body.
When people appear to have clotting and other blood disorders, blood testing can be performed to look for potential causes. This may reveal deficiencies or excesses of various compounds in the blood, providing important information about the origins of a patient's condition. Often it is the result of an inherited condition and there may be a family history of disease. In other cases, people acquire a genetic mutation in the womb, or experience a problem like prekallikrein deficiency as a result of an ongoing disease process.