In short. In blood collection tubes they are the same substance. When a label says sodium citrate, it means the trisodium salt of citric acid, that is trisodium citrate. What differs between tubes is not the name but the concentration and what else is added. PRP is prepared with sodium citrate or with ACD, a solution in which citrate is mixed with citric acid and dextrose.
Why two names
Citric acid can give up one, two or three hydrogen atoms to sodium, so mono-, di- and trisodium citrate all exist. The food and pharmaceutical industries tell them apart because their acidity differs. As a blood anticoagulant only the trisodium salt is used, usually as a hydrate. That is why tube descriptions use both names interchangeably.
How citrate keeps blood liquid
Clotting needs calcium ions. Citrate binds them, and the clotting cascade does not start until calcium is back in solution. The effect is reversible: if a protocol calls for activation, the physician adds calcium chloride. Platelets stay intact, which is why citrate became the PRP standard. Heparin works differently, through antithrombin, and is not used in plasma therapy, see heparin versus sodium citrate.
What actually differs
| Solution | Composition | Where it is used | For PRP |
|---|---|---|---|
| Sodium citrate 3.2 % | Trisodium citrate, about 0.109 mol/l | Light blue coagulation tubes, PRP tubes | Yes, if the tube is registered for PRP |
| Sodium citrate 3.8 % | Trisodium citrate, about 0.129 mol/l | ESR tubes, some older coagulation tubes | Less common in PRP devices |
| ACD, solutions A and B | Trisodium citrate, citric acid, dextrose | PRP and cell systems, apheresis | Yes, used in some systems |
| CPD, CPDA | Citrate, phosphate, dextrose, sometimes adenine | Donor blood bags | A storage preservative, not a PRP tube filling |
What to check on the label
- Anticoagulant name. Sodium citrate, trisodium citrate or ACD are suitable. Heparin, EDTA and clot activators are not.
- Concentration or blood ratio. Stated on the label or in the instructions. Fill the tube to the mark, otherwise the citrate to blood ratio is off.
- Intended use and class. The same citrate does not turn a laboratory tube into a PRP device. PRP as the intended use and class 2b must be in the registration certificate.
ReLife tubes use sodium citrate, the concentration is on the label and in the instructions we send with the documents. The tube also contains a separating gel, see PRP tubes with or without gel. Registration: Registration certificate RK-MP-5№016078.
Frequently asked questions
Are trisodium citrate and sodium citrate the same in a tube?
Yes. In medical tubes sodium citrate means the trisodium salt. The concentration may differ and is printed on the label.
Which is better for PRP, sodium citrate or ACD?
Both bind calcium and preserve platelets. ACD is slightly more acidic and contains dextrose, and is used in some device systems. The choice follows the physician's protocol and the device's intended use.