Application of Sodium Citrate in the Medical Field
As an anticoagulant, sodium citrate has well-defined application specifications and technical positioning in the field of clinical blood collection tubes. It is applied in blood collection tubes specifically for coagulation function tests (internationally marked with blue and black caps) and suitable for collecting blood samples for tests such as the four coagulation assays and erythrocyte sedimentation rate (ESR).
1. Anticoagulant Principle
The anticoagulant principle of sodium citrate is based on its unique chemical chelation effect. The mechanism is as follows: the citrate ions dissociated from sodium citrate can combine with calcium ions (Ca²⁺) in the blood to form a soluble complex that is difficult to dissociate, thereby reducing the concentration of dissociated calcium ions in the blood.
Calcium ions act as activators for various coagulation factors in the blood coagulation process (for example, the formation of prothrombin activator and the activation of thrombin both rely on calcium ions). When calcium ions are chelated, the coagulation process is blocked and blood will not clot, thus achieving the anticoagulant effect.
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2. Application
2.1 Controllable Anticoagulation Efficiency: A fixed dosage ratio of anticoagulant ensures consistent anticoagulation effects and reduces sample quality variations caused by human operational errors. Blood collection tubes achieve precise control over the anticoagulant-to-blood ratio. Typically, blue-capped tubes use a 9:1 volume ratio of blood to sodium citrate solution for four coagulation assays, while black-capped tubes adopt a 4:1 volume ratio of blood to sodium citrate solution for erythrocyte sedimentation rate (ESR) tests. This not only ensures effective anticoagulation but also maximally preserves the original state of blood components, providing clinical laboratories with standardized samples that meet testing requirements.
2.2 Specificity of Testing Items: It is only suitable for coagulation function tests and shall not be used for other types of tests such as routine blood tests and blood biochemistry tests. (The chelation of calcium ions may affect cell morphology or enzyme activity.)
2.3 Limited Anticoagulation Duration: Samples shall be submitted for testing promptly after collection (complete testing within 2 hours) to avoid component changes caused by prolonged storage.
3. Conclusion
Sodium citrate tubes provide reliable technical support for clinical coagulation function tests through a scientific anticoagulation mechanism and standardized application. Their action principle not only reflects the precise application of chemical chelation reactions in the medical field, but ensures the accuracy and repeatability of test results through strict operating specifications, making them an indispensable part in modern clinical laboratory testing.
Shanghai Tenghu Biotechnology is specialized in the blood collection tube reagents. We provide high-quality blood collection tube reagents such as sodium citrate, coupled with professional usage instructions. Based on customers' testing requirements and the characteristics of blood collection tubes, we offer recommendations on the rational selection of anticoagulant types as well as the dosage of dissolution and spray coating, so as to ensure the scientificity and reliability of medical diagnostics.
