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How to Get More Out of Your Saliva Collection & Handling

By 04.01.2022

How to Get More Out of Your Saliva Program: Powerful Considerations for Saliva Collection and Handling

How to Get More Out of Your Saliva Collection & Handling

Compared to traditional biofluids (i.e., blood), oral biofluids, such as saliva, hold a lot of potential for diagnostic testing. Saliva collection is minimally invasive, safe, and can be done quickly and in a variety of settings, giving it a big upper hand over (often) painful blood draws, which need to be done in a laboratory setting by a medical professional.1-3

Yet much of saliva’s potential in diagnostics remains untapped. Because saliva has not been as widely used as other biofluids, there is less awareness amongst scientists and researchers about the infrastructure, reagents, and best sample collection and handling practices required to implement an effective saliva testing program or research study. In addition, there is a large need for standardization to remove variability in workflows and ensure consistent data collection and analysis.4-6

To ensure that your saliva diagnostics program gets off on the right foot, we’ve collected some best practices and common considerations – from study design to sample collection and handling – for setting up a workflow and getting the most out of your efforts.

Designing your study or program

Regardless of the scope of your testing program or research study, the primary goal is to generate sensitive and selective detection of a specific salivary biomarker. This means eliminating any elements of your study design that can lead to sample contamination, participant noncompliance, or other confounding factors that could have unexpected downstream effects.

The location of sample collection does matter

The guidance for where sample collection should be based on compliance to the product specifications and proximity to testing labs. Sample collection for diagnostics should be administer by, or in the presence of a professional healthcare provider, and in a location near the testing facility.  Researchers can then directly oversee sample collection to analysis. Across participants, standardization to a pre-approved protocol is more easily achieved and verified. Locations that require further transport risk possible specimen degradation, cross-contamination or mishandling.

Conducting saliva collection in settings such as a person’s home or “in the field,” has its appeal to compared to approved centralized collection facilities (i.e., achieve a more rapid, decentralized sample collection) but there is a greater risk of human error without being in the presence of a professional healthcare provider. This includes contamination or deviation from protocols, as individuals without experience in sample collection may be responsible for sterile technique or (relatively) complex procedures. While procedurally challenging to account for errors, decentralized collection for surveillance of Sars-CoV-2 has been useful and will likely continue to be used in cases of infectious disease monitoring.7,8

Managing noncompliance 

Noncompliance can be a major issue with decentralized sample collection. In research areas where saliva testing has been more routinely performed, such as in salivary cortisol testing,  experts recommend several strategies for ensuring participant adherence, including:9

  • Explain the importance and the “why” behind protocol adherence around saliva collection and handling
  • Outline the detailed protocol and do one-on-one practice with participants, allowing them to ask questions
  • Provide clear, detailed instructions (i.e., written, video) and contact information for the research team
  • Make collection kits so all required materials are available on-demand
  • Remind participants at or before key sample collection times and of key steps in the protocol, including handling and freezing of samples post-collection.

Using these strategies can help ensure the consistency of sample collection and adherence to the study protocol or diagnostic workflow. However, protocol for clinical studies requires the sample be collected in the presence of a trained healthcare professional.

Collecting saliva samples from patients

a sample collection scheme must include standardized timing for saliva collection. Biological factors can affect the concentration of specific salivary analytes and their effective collection. 10 For instance, many salivary hormones follow a diurnal pattern of expression, and therefore, Other pivotal factors include the method of saliva collection, anatomical location of collection, and sample volume.

“For best results, saliva donors should be instructed to refrain from eating, drinking, using tobacco products, or chewing gum for at least 30 minutes for best results.” See Specimax Dx Instructions for Use for more details.

Variations in salivary glands secretion

Not all oral samples are created equal. Whole saliva is a complex mixture of biomolecules and contains oral fluids from various salivary glands, including the parotid, submandibular, sublingual, and other minor secretory glands. The secretions from these glands differ in composition and thus, sampling them individually versus whole saliva can provide different diagnostic results.

In addition, saliva composition changes in response to taste, smell, and even the stimulation of chewing.11 Another factor to consider is blood contamination in the saliva, which contains certain biomarkers at much higher concentrations than is present in saliva. This can be particularly concerning in populations where oral health is impacted by gingivitis, periodontal disease, HIV, tobacco use, and other factors and can be controlled by incorporating careful screening methodologies for saliva samples.12-14 Taken together, understanding the presence or absence of a specific salivary biomarker in whole saliva or secretions from a particular gland, is a critical prerequisite to establishing a reliable testing scheme.

Saliva sample collection methods

A standard practice for saliva collection is the collection of unstimulated whole saliva, using the passive drool method. Whole saliva is most easily collected using collection tubes with funnels to prevent spillover. Saliva donors should allow saliva to pool in their mouths and then drool the saliva into the top of the funnel affixed to the saliva collection device. Consider the liquid portion of the saliva, not the bubbles, when determining if enough saliva has been collected.

Thermo Fisher recently launched its line of SpeciMAX Saliva Collection Kits that addresses sample collection concerns with a funnel top into a standardized test tube. Depending on the application, raw and stabilized variations of the tube can be purchased.

When an analyte from a specific gland is required or populations are being studied that are unable to do passive drool (i.e., infants or geriatric populations with xerostomia), a variety of swabs are available for different age groups and analytes. If self-administration is required for your testing scheme, the swab method may be technically challenging and suffer from noncompliance issues.

Choosing which collection method to use depends on a combination of the age of participants, target analyte, number of required samples, sample volume, sample storage, and whether or not assistance will be provided for sampling.

Heratherm 400L General Protocol Oven for sample storage

Sample handling for saliva

Maintaining sample integrity for the short- or long-term is critical to running a successful saliva testing program. The choices made about cold chain management and workflow manipulation can affect analyte concentration and therefore, the reliability of diagnostic results.

Cold Chain Management

Though some analytes are stable at room temperature, many are not.15 For example, the SpeciMAX™ Dx Stabilized Saliva Collection Kit from Thermo Fisher Scientific are to be stored at 15–30°C. In general, some analytes still require storage with inhibitors to prevent degratation.19

Temperature sensitivity can severely limit the ability to implement an at-home or decentralized testing system. Transporting saliva samples after collection can require dry ice, increasing the complexity and cost of testing, ultimately, limiting the scope of participation.

Post-collection handling

Many biomolecules are sensitive to freeze-thaw cycles. Accordingly, minimizing freeze-thaw cycles can help maintain sample integrity. Certain hormones, such as progesterone and estradiol, are sensitive to freeze-thaw cycles while others – like DNA – are more robust though there is still a decrease in quality the more a sample is refrozen.20

To avoid freeze-thaw cycles, it may be necessary to aliquot an individual sample into multiple cryovials and use one aliquot at a time for analysis. This may create a labor-intensive workflow and be challenging with viscous whole saliva samples, but necessary to ensure reliable results.

Implementing best practices using saliva collection with SpeciMax

There’s a lot of planning that goes into establishing a trusted saliva collection and testing workflow. Thermo Fisher Scientific’s SpeciMax whole saliva collection tubes help address many of the considerations raised above: They have a simple design with an easy-to-use collection funnel to minimize mess during passive drool collection, pre-marked lines to determine when sampling is complete, and compatibility with automated liquid handlers to minimize manual pipetting steps. The SpeciMax collection tubes also enable efficient use of refrigeration and freezer space, allowing labs to fit 6 times as many SpeciMax tubes as 50 mL conical tubes in the same space.

Learn more about SpeciMAX Dx Saliva Collection Kits for In Vitro Diagnostics and see how Thermo Fisher Scientific can help you establish a powerful high-throughput saliva testing program from sample collection and preparation to PCR analysis and results.

Read More Related Articles

  • Triumphs for Saliva as a Diagnostic Fluid
  • The Future of Saliva Biomarkers in the Clinic

This article contains product information intended for General Laboratory Use. It is the customer’s responsibility to ensure that the performance of the product is suitable for customer’s specific use or application.

References:

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