Logistics: Shipping cfDNA Without Ruining the Sample

The most dangerous part of a liquid biopsy's journey is not the needle stick or the PCR machine—it is the FedEx truck.

Once you have collected and processed your sample, you are fighting against two enemies: Time and Temperature. If either wins, white blood cells lyse, or DNA degrades, and the result is invalid.

Here is how to navigate the two main shipping protocols.

Protocol A: The Frozen Plasma Route

This is the standard for labs that require you to process the sample in-house (using the double-spin method).

* The Sample: Cell-free plasma in a cryovial.
* The State: Frozen solid (-20°C or -80°C).
* The Threat: Thawing. As plasma thaws, ice crystals shift and shear the long DNA fragments. If a sample thaws and refreezes during shipping (e.g., sitting on a tarmac), the DNA integrity is compromised.
* The Solution: Dry Ice.
* Ice packs (blue gel packs) are NOT cold enough. They keep things "cool" (4°C), they do not keep things frozen.
* You must use at least 2–3 kg of dry ice for an overnight shipment to ensure the sample never enters the liquid phase.

Protocol B: The Stabilized Whole Blood Route

This is for labs that use Streck or PAXgene tubes, allowing you to ship whole blood.

* The Sample: Whole blood in a glass or plastic tube with a preservative.
* The State: Ambient / Room Temperature.
* The Threat: Extreme Temperatures (Heat or Freezing).
* Freezing: This is the #1 error. If you put a Streck tube in the freezer, the water inside the blood cells expands and bursts the cell membranes. The preservative cannot stop physics. A frozen whole blood tube is 100% hemolyzed and useless.
* Heat: Sitting in a dropbox in Arizona in July (>37°C) can overwhelm the preservative, leading to cell metabolism and lysis.
* The Solution: Insulated Box at Room Temp.
* Ship with a "room temperature pack" (a gel pack that has been left on the counter, not frozen) to act as a thermal buffer against spikes in outside temperature.
* Do NOT include ice.

The "Friday Draw" Dilemma

If you draw blood on Friday afternoon and FedEx doesn't pickup until Monday:
1. If using EDTA: You must spin, separate, and freeze the plasma immediately. You cannot leave EDTA blood in the fridge for the weekend.
2. If using Streck: You can leave the tube at room temperature (away from windows/sun) over the weekend and ship Monday.

Summary

* Plasma: Ship on Dry Ice.
* Whole Blood: Ship Ambient. NEVER FREEZE.

Treat the shipment as part of the medical procedure. A bad shipment = no diagnosis.