Quick facts
- A lithium heparin tube is a blood collection tube whose additive is the lithium salt of heparin, used to keep whole blood fluid so the plasma can be tested.
- In the United States a tube of this kind is a named Class II entry at 21 CFR 862.1675, the regulation for sample tubes with an anticoagulant and for serum separators.
- In Canada a blood collection tube is a Class II medical device under the Medical Devices Regulations, and a Class II device needs a medical device licence under section 32.
- A heparin tube is not for coagulation testing; the heparin in the tube interferes with the assay, so a coagulation sample goes into a citrate tube and the order of draw follows CLSI GP41.
- The draw volume is part of the device: ISO 6710 covers the single-use container for venous blood specimen collection, and a short draw changes the additive-to-blood ratio.
- The entries and rule text quoted here were checked against the openFDA device classification API and the Regulations on 2026-10-06.
A lithium heparin tube is the anticoagulant tube a laboratory reaches for when a chemistry result is needed quickly. It is used for plasma chemistry, for some electrolyte panels and for tests where a delay in clotting would be a problem. The tube is a Class II device, and the additive inside it is the reason the tube cannot be used for every test.
What is a lithium heparin tube and what is it used for?
The additive is the lithium salt of heparin, which stops blood from clotting by blocking the clotting cascade. Because the anticoagulant stays in the plasma rather than being removed, the plasma can be separated by centrifuge and tested directly. That makes the tube a fast route to a chemistry result, and it is why a heparin tube is common in an urgent-care or point-of-care setting.
The same property rules out other uses. A coagulation test measures the clotting cascade, and a tube that blocks the cascade will not measure it. So a prothrombin time or an activated partial thromboplastin time goes into a citrate tube, not into a heparin tube, and the order of draw keeps the heparin tube from contaminating the tube that follows it.
How do Canada and the United States classify the tube?
The two countries reach the same class from different directions.
| Item | Canada | United States |
|---|---|---|
| Tube with anticoagulant | Class II device, licence under s. 32 | Class II, 21 CFR 862.1675 |
| Serum separator tube | Class II | Class II, same regulation |
| Capillary blood collection tube | Class I | Class I, 21 CFR 864.6150 |
| Coagulation tube (citrate) | Class II | Class II, same regulation family |
| Basis of the class | The device and its intended use | The named entry and product code |
In the United States the entry covers sample tubes with an anticoagulant and serum separators, and a product filed under that entry is Class II. In Canada a blood collection tube is a Class II medical device and needs a medical device licence under section 32 supported by a quality-system certificate against ISO 13485.
The distinction that moves work is between the tube and the additive. The class follows the intended use recorded for the tube; a tube sold as a heparin tube and then used for a coagulation assay is used outside the use its licence describes.
Why does the order of draw matter?
Because the additive in one tube can carry into the next. CLSI GP41 sets the order in which tubes are drawn and the way each tube is mixed, and CLSI GP39 covers the collection, transport and processing of specimens for plasma-based coagulation assays. The order is not a preference; it is the step that stops a heparin tube from biasing the tube that follows it.
A short draw is the second hazard. ISO 6710 fixes the draw volume for a venous collection container, and a partly filled tube carries too little blood for the additive inside it. The result is not a smaller sample of the same plasma; it is a sample with a different additive-to-blood ratio, and an assay read from it can be wrong.
Which standard covers interference from the additive?
The interference question is answered by a standard rather than by the class. CLSI EP07 covers interference testing in clinical chemistry, and it is the document a laboratory reads when a result looks inconsistent with the patient. A lithium heparin tube is the right tube for the tests it was made for, and a separate tube for the tests it was not.
For a laboratory the practical step is to keep the collection order and the tube colour on the same card, and to record the tube type with the result. That record is what shows, after the fact, that the correct tube was used.
What do the two rulebooks actually say?
The entries are short, and the difference between them is the point of this article.
| Rule or entry | Wording in the source | Effect on a lithium heparin tube |
|---|---|---|
| 21 CFR 862.1675, US | Tubes, vacuum sample, with anticoagulant | Named Class II entry |
| 21 CFR 864.6150, US | Tube, collection, capillary blood | Class I for a capillary tube |
| MDR section 32, Canada | A device licence is required for a Class II device | Licence before sale |
| MDR section 45, Canada | An establishment licence for the activity | Who may import or sell |
| ISO 6710, ISO | Single-use containers for venous blood collection | Draw volume and colour coding |
Read together, the five lines explain why a supplier cannot move the class by relabelling a tube. A tube described as a general collection tube while it holds heparin is described against the text, not against the cap.
Which consumables does a collection bench restock?
A blood collection bench runs on the same supplies as any other bench. The seventy percent alcohol prep pads are the skin-prep item used before every draw, and the sterile centrifuge tubes carry the separated plasma away from the bench. A laboratory that also monitors its own steriliser pairs the sterilization monitoring collection with the 24-hour monitoring five-pack trial. Laboratories and multi-site groups ordering at case level use the wholesale ordering page, and the B2B wholesale collection lists the lines held for institutional buyers. Reselling? become a distributor.
Which tests use a lithium heparin tube?
A heparin tube is chosen for a plasma chemistry result that is needed quickly, and for analytes that are stable in plasma. It is a common tube for a blood-gas panel drawn at the bedside, for many routine chemistry panels, and for tests where a serum tube would take too long to clot. It is not the tube for a coagulation assay, because the heparin blocks the cascade the assay measures.
The lithium rather than the sodium salt is the usual choice for a chemistry panel, because the sodium load of a sodium heparin tube can shift a sodium result. That is a small effect, but it is the reason the two salts are stocked as separate tubes rather than used interchangeably. A laboratory that stocks one salt and not the other should say so on the collection card, so that a draw does not have to be repeated to get the right tube.
Sources
- 21 CFR 862.1675, Tubes, vacuum sample, with anticoagulant
- 21 CFR 864.6150, Tube, collection, capillary blood
- 21 CFR 864.3250, Container, specimen, sterile
- Medical Devices Regulations, SOR/98-282, full text
- openFDA device classification API
- ISO 6710:2017, single-use containers for venous blood specimen collection
- CLSI GP41, collection of diagnostic venous blood specimens
- CLSI GP39, processing of specimens for coagulation testing
- CLSI EP07, interference testing in clinical chemistry
- ISO 13485:2016, medical devices quality management
- ISO 14971:2019, risk management for medical devices
- Health Canada, medical devices guidance
- Public Health Ontario, laboratory services test index
- CLSI, clinical and laboratory standards
- US FDA, medical devices
- Standards Council of Canada
- CCOHS, OSH answers
- Canadian Dental Association
A count of how many tubes a draw station opens is a count that is hard to rebuild later. The printable collection order and lot log is a blank form with columns for the tube type, the order, the lot and the date, so a mis-ordered draw is visible on the day. The collection log generator on the same page sizes the form to the number of draw stations a site runs. No account and no sign-up are needed to open either one.
Every collection setup is different. Ask a compliance specialist and you will get a written answer specific to your equipment and province, with the regulation or standard it is based on cited.
Related reading
- Blood Collection Tube Systems in Canada vs the US: Which Order?
- Capillary Tubes in Canada vs the US: Which Size and Standard?
- Microcentrifuge Tubes in Canada vs the US: Which Standards?
CliniEco Medical supplies eye care, laboratory and dental consumables of the kind described in this article. MDEL #35334. This article is written for optometry, laboratory and procurement professionals and is not legal advice; the class of a device and the records kept by a clinic belong to the manufacturer and to the requirements that apply to it.
Frequently Asked Questions
Is a lithium heparin tube a Class II device in the United States?
Yes. A sample tube with an anticoagulant is a named Class II entry at 21 CFR 862.1675, the same regulation that covers serum separator tubes.
How does Canada classify the same tube?
In Canada a blood collection tube is a Class II medical device, and a Class II device needs a medical device licence under section 32 of the Medical Devices Regulations, supported by an ISO 13485 certificate.
Can a lithium heparin tube be used for a coagulation test?
No. The heparin in the tube blocks the clotting cascade the assay is measuring. A coagulation sample goes into a citrate tube, and the order of draw follows CLSI GP41.
What happens if the tube is only partly filled?
The additive-to-blood ratio changes. ISO 6710 fixes the draw volume for a venous collection container, so a short draw is not a smaller sample of the same plasma but a sample with too much additive.
What is the mix step for a heparin tube?
A heparin tube is mixed by gentle inversion immediately after the draw, and the invert count is given by CLSI GP41. The step is part of the collection procedure, not an optional extra.
Does the tube colour decide the additive?
The colour coding is a convention fixed by ISO 6710, and the licensed label is the authority. A tube should be identified by the additive named on its label, not by the colour of the cap alone.
What does the class change for a supplier?
In Canada a Class II device needs a licence under section 32 held by the manufacturer, while the Canadian seller holds an establishment licence under section 45. In the United States the product reaches the market through premarket notification unless its named entry is exempt.
0 comments