What are the effects of different EDTA anticoagulants in biochemical testing?

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What is EDTA?

Ethylenediaminetetraacetic acid (EDTA) is a commonly used anticoagulant for testing. There are three types: disodium (EDTA-Na2), dipotassium (EDTA-K2) and tripotassium (EDTA-K3).

Because potassium salt is more soluble than sodium salt, EDTA-K2 and EDTA-K3 are better than EDTA-Na2; and because the pH of EDTA-K2 is lower than that of EDTA-K3, it can compensate for cell wrinkles caused by osmotic pressure. Therefore, EDTA-K2 stands out as the most commonly used EDTA anticoagulant in clinical practice. The anticoagulant tube is marked with a purple cap.

The anticoagulant mechanism of EDTA

Ca2+ is an indispensable factor for both internal and external blood coagulation pathways. EDTA forms a stable chelate with Ca2+ in the blood to play an anticoagulant effect.

The impact of EDTA-K2 on biochemical projects

Determine the impact of the project

Project Impact Reason

K+ ↑ EDTA-K2 itself contains potassium ions, causing high blood potassium

Ca2+ ↓ EDTA can chelate Ca2+ ions in blood samples, which is also the anticoagulant mechanism of EDTA

Mg2+ ↓ EDTA chelated Mg2+ ions in the blood sample to reduce blood magnesium. In addition to Ca2+ and Mg2+, EDTA can also chelate other divalent metal ions, such as Mn2+, Fe2+

ALP ↓ Mg2+ is the activator of ALP activation center, so EDTA-K2 will reduce the activity of ALP

Clinically, when the phenomenon of high potassium, low calcium, and low ALP occurs, first consider:

①The situation of using wrong blood collection tube: EDTA-K2 anticoagulant tube is used for blood collection for biochemical testing;

If the blood collection tube is correct, be wary of the following errors:

② EDTA interference caused by irregular blood sampling sequence: first use EDTA tube to collect blood for routine blood testing, resulting in the blood sampling needle carrying a small amount of EDTA anticoagulant or even EDTA anticoagulant blood flowing back along the blood sampling needle, thereby contaminating the next biochemical tube.

Projects that may affect

Through controlled experiments and statistical analysis, different documents describe the biochemical items that EDTA-K2 may have an impact

▪ Liver function: AST, ALT, TP, TBIL, DBIL

▪ Kidney function: BUN, UA

▪ Blood lipids: CHOL, HDL-C, LDL-C

▪ Myocardial enzymes: LDH, CK

▪ Other: HCO3-, AMY

The reasons for the impact may include:

① EDTA chelates divalent metal ions. These ions may act as prosthetic groups (activators or stabilizers) of certain enzymes. The changes in the existence of these ions change the activity of enzymes.

②EDTA has penetrating and diluting effects, which may interfere with the accuracy of biochemical testing

Although there is no recognized definitive evidence for the effect of EDTA on biochemical indicators other than ions and ALP, in order to eliminate this uncertain pre-analysis influencing factors, it is recommended to use lithium heparin anticoagulation tubes to collect blood samples for biochemical testing.

Whether it is EDTA-K2, EDTA-K3 or EDTA-Na2 anticoagulant, Desheng can provide it. In addition to anticoagulants, the series of products such as coagulants, separating gels, and silicone oils in our blood collection tube additives are the company's main products.