Plasma

These added substances intervene at different stages of the coagulation process, and these stages are used to highlight the factor under investigation.

To guarantee that the mix with the added substances is correct at the time of the blood test, the sampling test tube must be marked indicating that its filling has been completed.

• Plasma with lithium and heparin (green tube) is indicated for practically all factors of clinical chemistry and serology and can be an alternative to serum when small volumes are required (small mammals, birds, reptiles, etc.).
• Plasma with iodoacetic acid (grey tube) is used to measure glucose and lactate when it is not possible to perform a correct centrifugation of the serum or the total blood.
• Plasma with citric acid (light blue tube) is used for a concentration ratio of 1/10, for coagulation analyses (prothrombin time, Quick time, thrombin time, von Willebrand factor antigen, fibrinogen). If it is not possible to perform the analysis immediately, the citrated plasma should be sent frozen or as cold as possible to stabilise the coagulation factors.
• Plasma with EDTA (purple tube) is indicated for various parameters in haematology and clinical chemistry (e.g. ammoniac) and can also be an alternative to serum, albeit limited.
• EDTA (ethylenediaminetetraacetic acid) is a complex chelating agent stabilised by cations.
• Plasma-EDTA is not valid for measuring various electrolytes or for evaluating enzymatic reactions involving cations.

Plasma treated with aprotinin is indicated for measuring instable enzymes and hormones (e.g. ACTH).