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This page describes products and general use; it is not medical advice.
Short answer: a PAXgene tube is a blood collection tube that already contains a stabilizing additive, so the RNA (or DNA) in the sample does not degrade between the draw and the lab. The name belongs to Qiagen’s PAXgene family; the tubes it is often compared with, Streck’s cell-free DNA tube and the Tempus blood RNA tube, are different products with different manufacturer instructions. They are not interchangeable with each other or with the extraction kit a laboratory has validated.
Who uses it: clinical and research laboratories, the phlebotomy staff who collect for them, and biobanks that store stabilized blood.
What a PAXgene tube is
The PAXgene Blood RNA Tube (IVD) is an evacuated blood collection tube that holds a reagent which stabilizes intracellular RNA as the blood enters the tube. Qiagen lists it as catalog 762165, a box of 100 tubes sold by BD, and it is used with the PAXgene Blood RNA Kit as the PAXgene Blood RNA System. It is intended for in vitro diagnostic use, and Qiagen states that its performance was established for the FOS and IL1B transcripts.
Its purpose is to preserve the RNA profile of the sample at the moment of collection, so that gene-expression results reflect the sample and not the time spent in transit.
How it is built
Per Qiagen’s product page, the PAXgene Blood RNA Tube is 16 x 100 mm, has a BD Hemogard closure with a red stopper, holds 6.9 ml of additive and is designed for a 2.5 ml blood draw. Because the tube contains a fixed additive volume, the blood-to-additive ratio depends on the tube filling to its intended draw volume.
PAXgene vs Tempus vs Streck cell-free DNA tubes
These three names come up together because all of them stabilize a blood sample before analysis. They stabilize different targets, which is the main difference.
| Tube | Stabilizes | Product points from the manufacturer’s documents |
|---|---|---|
| PAXgene Blood RNA Tube (IVD) | Intracellular RNA | 2.5 ml draw volume; RNA stable 3 days at 18-25 C or 5 days at 2-8 C; frozen storage guidance on the Qiagen product page |
| Streck Cell-Free DNA BCT CE (IVDR) | Cell-free DNA in plasma, plus a cell preservative (contains K3EDTA) | Fill completely; sample stability table in the IFU; empty tubes must not be frozen (Streck IFU) |
| Tempus Blood RNA Tube | RNA in blood stabilized with Tempus reagent | Thermo Fisher sells a separate MagMAX RNA isolation kit for Tempus-stabilized blood; that kit is labelled for research use only |
Each tube has its own manufacturer documents. Use the instructions for use that ship with the lot you hold.
Specifications that matter
| Item | PAXgene Blood RNA Tube (IVD) | Streck Cell-Free DNA BCT CE (IVDR) |
|---|---|---|
| Tube size and closure | 16 x 100 mm; BD Hemogard, red stopper | Contains K3EDTA anticoagulant and a cell preservative in liquid medium |
| Fill | 2.5 ml draw (6.9 ml additive) | Fill completely; over- or underfilling gives an incorrect blood-to-additive ratio |
| Sample stability, room temperature | RNA: up to 3 days at 18-25 C | Cell-free DNA and cellular genomic DNA: 14 days at 6-37 C; epithelial (tumor) cells: 7 days at 15-30 C |
| Sample stability, refrigerated | RNA: up to 5 days at 2-8 C | Within the 6-37 C range above |
| Frozen storage | -20 or -70 C, up to 11 years on current data; up to two freeze/thaw cycles | Do not freeze specimens in glass tubes; do not freeze empty tubes |
| Intended use | In vitro diagnostic; tied to the PAXgene Blood RNA Kit | In vitro diagnostic; for use by laboratory professionals |
How to choose
- Match the tube to the analyte. The PAXgene Blood RNA Tube is for intracellular RNA; the Streck tube is for cell-free DNA.
- Match the tube to the downstream kit. The PAXgene Blood RNA Tube is described as part of a system with the PAXgene Blood RNA Kit, and Thermo Fisher documents a separate kit for Tempus tubes.
- Check the regulatory status of the version. Qiagen lists the PAXgene Blood RNA Tube as an IVD product; the Streck IFU is an IVDR document; the Thermo Fisher kit for Tempus tubes is labelled research use only.
Collection instructions, storage and the stability trap
Collection instructions
Each stabilizer tube comes with its own instructions for use covering its position in the order of draw, any waste or discard tube, and mixing. These differ between products, so a laboratory’s phlebotomy procedure and each tube’s IFU govern. See the phlebotomy lab supply checklist for related supplies.
Storage
For PAXgene RNA tubes the windows are 3 days at room temperature (18-25 C) and 5 days at 2-8 C. For frozen storage Qiagen states the tubes should be frozen in a wire rack, not an expanded polystyrene foam tray, and that for storage below -20 C they are first frozen for 24 hours at -20 C and then moved to -70 C.
The Streck stability trap
The Streck IFU contains two numbers that readers often merge. Its stability section says samples are stable for up to 14 days at 6-37 C. Its precautions say whole blood should be stored at 18-25 C for up to 7 days before processing to plasma. Follow the IFU for your product version and assay, since older research-use material cites different figures. Empty Streck tubes are acceptable at 2-40 C for short-term storage of up to 14 days, must not be frozen, and must not be used past expiry. Streck also states that specimens in its glass tubes must not be frozen.
Label specimens carefully; see specimen labeling error prevention.
FAQ
What is a PAXgene tube used for?
It collects blood and stabilizes intracellular RNA so gene-expression analysis reflects the moment of collection. The Blood RNA Tube is used with the PAXgene Blood RNA Kit.
Is a Streck tube the same as a PAXgene tube?
No. The Streck Cell-Free DNA BCT preserves cell-free DNA with a cell preservative and K3EDTA, has its own instructions for use, and is a different manufacturer’s product.
What is a cell free DNA tube?
A blood collection tube whose additive (in Streck’s case K3EDTA plus a cell preservative) is meant to preserve cell-free DNA in the sample until plasma processing. Streck’s Cell-Free DNA BCT is one such tube; its IFU gives the fill and storage rules.
How long is RNA stable in a PAXgene tube?
Per Qiagen: up to 3 days at room temperature, up to 5 days at 2-8 C, and up to 11 years frozen at -20 or -70 C on current data.
Is a Tempus tube the same as a PAXgene tube?
No. Tempus Blood RNA Tubes are a different product line from a different manufacturer, and Thermo Fisher documents a separate RNA isolation kit for them. Qiagen’s PAXgene Blood RNA Tube is tied to the PAXgene Blood RNA Kit.
Is a PAXgene Blood RNA Tube for diagnostic use?
Qiagen lists it as intended for in vitro diagnostic use, with performance established for the FOS and IL1B transcripts.
For a wider checklist of what a genetic-testing laboratory stocks, see the genetic testing lab supply checklist, and for downstream work see RNA extraction protocol basics. Related term: biospecimen.
Sources
- Qiagen, PAXgene Blood RNA Tubes (IVD) product page, https://www.qiagen.com/us/products/discovery-and-translational-research/sample-collection/paxgene-blood-rna-tubes, checked 2026-10-30.
- Streck, Cell-Free DNA BCT CE instructions for use (IVDR), PDF copy at https://pathologie.uk-essen.de/wp-content/uploads/2025/08/01_Cell-Free_DNA_BCT_CE_IFU_IVDR.pdf, checked 2026-10-30.
- Thermo Fisher Scientific, MagMAX for Stabilized Blood Tubes RNA Isolation Kit (Compatible with Tempus Blood RNA Tubes) quick reference card, https://documents.thermofisher.com/TFS-Assets/LSG/manuals/cms_084750.pdf, checked 2026-10-30.
