Citrated blood
As a medical term, citrated blood refers to a blood sample that has been taken for examination purposes and made incoagulable by adding a defined amount of sodium citrate or isotonic sodium citrate solution (3.8%). Citrated blood is also used for blood transfusions .
Biochemical background
Citrate binds the calcium ions in the blood. Since calcium is an important factor in blood clotting , the blood can no longer clot .
use
Citrated blood is required in particular for the determination of the coagulation factors in the blood. It is removed and examined at almost every routine examination, for example before an operation.
Laboratory practice
A vacuum blood collection tube of 5 ml contains 0.5 ml of 3.8% sodium citrate solution and is to be filled up to the mark with 4.5 ml of venous blood from a peripheral venipuncture that is as free as possible. The blood must be examined immediately (within 2 hours) after collection.
The rate of sedimentation of the blood cells , which is used for general inflammation diagnostics, is also determined from citrated blood.
In addition to citrated blood, there are other methods of making blood incoagulable for examination purposes:
Other examination methods use coagulated blood; the laboratory values sought are determined from the excess blood serum . Analogous to the citrate buffer of the citrated blood, the Alsever solution is sometimes used.
Laboratory values that can be determined from citrated blood
- Thrombin time (PTZ) or Quick value
- partial thromboplastin time (PTT)
- Fibrinogen
- individual coagulation factors
See also
Web links
- Laboratory examinations of coagulation ( Memento of January 13, 2005 in the Internet Archive )
