What are the methods for measuring plasma calcium conversion time

The main methods for determining plasma procalcitonin time include test tube method, instrument method, siliconized tube method, activated clotting time method, and prothrombin time method.

1. Test tube method:

The test tube method is a traditional manual measurement method, in which sodium citrate anticoagulant plasma is mixed with calcium chloride solution in proportion and placed in a 37 ℃ water bath to observe the formation time of fibrin. This method is simple to operate but is greatly affected by temperature and pH values, requiring strict control of experimental conditions. Clinically, it is commonly used to screen for abnormalities in endogenous coagulation pathways, with a normal reference value of 2-4 minutes.

2. Instrumental method:

uses a fully automatic coagulation analyzer to detect and monitor the plasma coagulation point through optical or mechanical methods. The instrument method has good repeatability and can simultaneously detect multiple samples, with results accurate to the second level. Common equipment uses the principle of magnetic bead method. When the viscosity of plasma changes and the amplitude of magnetic bead movement decreases, it is determined as the coagulation endpoint, which is suitable for large-scale detection.

3. Silicified tube method:

uses siliconized glass test tubes for measurement, which can reduce the interference of activated coagulation factors on the glass surface. This method is 1-2 minutes longer than the ordinary test tube method and is more sensitive to reflecting endogenous coagulation factor deficiency, especially suitable for hemophilia screening. It should be noted that repeated use of siliconized tubes will reduce the coating effect.

4. Activated clotting time method:

Adding activators such as kaolin or tannic acid during the process of decalcification accelerates the activation of contact factors. This method shortens the detection time to 50-100 seconds, improving the sensitivity of monitoring heparin treatment. If the activation results are still prolonged, it indicates the presence of coagulation factors VIII, IX, XI deficiency or inhibitors.

5. Prothrombin time method:

initiates an exogenous pathway by adding tissue thromboplastin, and combines calcium ion determination to determine the time to calcium replenishment. This method can distinguish between endogenous and common pathway abnormalities. When the time for calcium replenishment is prolonged and PT is normal, it indicates hemophilia or factor XII deficiency. International standardized reagents are required to ensure comparability of results.

Blood should be collected on an empty stomach before determining the time of plasma calcium conversion to avoid lipid blood affecting the results. When collecting blood, pay attention to completely mixing the anticoagulant to avoid hemolysis or coagulation of the specimen. During the testing period, maintain stable room temperature and rest for 30 minutes after vigorous exercise before testing. Abnormal results are recommended to be further examined in combination with activated partial thromboplastin time, coagulation factor activity, etc. If necessary, vitamin K supplementation or replacement therapy should be performed under the guidance of a hematology department.