Diagnostic labs rely on temperature-controlled transport every day, but when it comes to refrigerated specimens, small temperature deviations can create outsized problems. From the moment a sample is collected to when it reaches the lab, it moves through multiple environments, each introducing potential variability.
To better understand how to control that risk, it helps to break the problem down into four key questions.
What types of specimens require refrigeration (2–8°C)?
A wide range of diagnostic specimens must be kept within a refrigerated range during transport, typically 2–8°C. This includes blood samples (such as plasma and serum), microbiology specimens, molecular and genetic testing samples, and certain immunology or pathology materials.
These specimens are temperature-sensitive because their biological components can change quickly outside of controlled conditions. Enzymes can degrade, cells can break down, and microbial activity can shift, all of which directly impact the accuracy of test results. Maintaining a stable temperature range isn’t just a guideline, it’s essential to preserving specimen integrity.
What happens if these specimens face a temperature excursion?
When a refrigerated specimen moves outside the 2–8°C range, even briefly, the effects can be significant. The issue isn’t always obvious at first, but it shows up in downstream results and operations.
Temperature excursions can lead to:
- Sample degradation or instability
- Changes in bacterial growth for microbiology samples
- Invalid or inconclusive test results
- Redraws, requiring patient samples to be recollected
- Delays in lab workflows and reporting
Studies have shown that up to 70% of laboratory errors occur in the pre-analytical phase, before testing even begins. That means many issues originate during collection, handling or transport, often due to uncontrolled temperature conditions.
What helps minimize temperature excursions during transport?
Not every variable in specimen transport can be controlled. Routes change, delays happen, and environmental conditions fluctuate. However, packaging plays a critical role in reducing how much those variables impact the sample.
A well-designed packaging system helps stabilize conditions throughout the journey. This typically includes insulated shippers and a consistent packout process, and equally important is the refrigerant used inside the package.
When the refrigerant performs consistently, it helps absorb environmental changes instead of amplifying them. This becomes especially important in multi-stage transport, where small fluctuations at each step can compound over time.
Why choose a 5°C PCM pack over a gel pack?
Standard gel packs are widely used because they’re simple and familiar, but their performance is often misunderstood. Because they are water-based, gel packs freeze around 0°C (32°F). In practice, they are usually conditioned below that temperature, meaning they often enter a shipment much colder than intended.
This creates a pattern where the shipment starts too cold and then gradually warms over time. Instead of maintaining a stable temperature, gel packs move through a broad range—introducing variability at both ends.
This typically results in:
- Overcooling at the beginning of the shipment
- Less predictable temperatures as the pack warms
- Performance that varies depending on route and conditions
In contrast, 5°C phase change material (PCM) packs are designed to hold a specific temperature point. Rather than passively cooling, they actively stabilize around that phase change temperature, helping maintain a more consistent 2–8°C environment.
This difference becomes especially important when looking at seasonal extremes. In colder conditions, gel packs can increase the risk of freezing sensitive specimens. In warmer conditions, they may not provide consistent protection against rising temperatures. PCM packs, on the other hand, are designed to perform more predictably across both scenarios by maintaining a controlled temperature closer to the target range.
A More Controlled Approach to Refrigerated Transport
Specimen transport will always involve some level of variability. The goal isn’t to eliminate every variable, it’s to prevent your packaging from adding to the problem.
By using a refrigerant designed to maintain a defined temperature, labs can create more stable conditions throughout the shipping process. This leads to more consistent outcomes, fewer disruptions, and greater confidence in the integrity of every sample.
The Bottom Line
Refrigerated specimens don’t fail because of one major breakdown. More often, it’s the result of small temperature inconsistencies that build up over time.
Controlling temperature from the start, with the right packaging choices, makes it easier to maintain stability across the entire journey.
And that consistency is what ultimately protects both the sample and the results that depend on it.
“At Akuratemp, we strive for excellence in the field of thermal packaging with products that provide sustainability in their reusability, peace of mind in their precision, and an optimal weight-to-volume ratio that assists in the reduction of shipping and storage costs.”
Harshul Gupta, CTO
