In short: Collecting blood carries hazards, particularly in children, and the stress and pain of sampling can themselves raise the hormones being measured and cause false-positive results. A 2025 validation study in Endocrine Connections built a method that can measure catecholamine metabolites in as little as 20 µL of saliva, and tested how well three different collection swabs recover them, including Micro•SAL for Children. It shows why the choice of collection device matters as much as the lab assay.
This article describes published research. Oasis Diagnostics devices are for research use. Nothing here is medical advice.
Key takeaways
- The study developed and validated an LC-MS/MS assay for metanephrine, normetanephrine and 3-methoxytyramine in saliva, designed to work with the tiny volumes available from newborns and from people with a dry mouth.
- A sample volume as low as 20 µL was acceptable for all analytes, though 50 µL gave better accuracy and precision.
- Of three swabs tested, two were suitable for newborns (Micro•SAL for Children and the SalivaBio infant swab) and one (Salivette) for adults only.
- At the middle calibration levels, recovery from the Micro•SAL for Children collector was 90–113%, compared with 93–104% for the SalivaBio swab and 85–107% for the Salivette.
- Analytes were stable on the swab for 6 hours at room temperature and for at least a week at −20 °C.
Why saliva for hormone testing?
Stress and anxiety trigger release of catecholamines such as epinephrine and norepinephrine. The authors explain that it is clinically challenging to tell tumour-driven hormone elevation from ordinary stress-related elevation, and that sampling saliva at home without stress and pain has the potential to reduce false-positive results and repeat sampling. They describe saliva as simple to process and non-invasive, which makes it a preferred alternative in paediatric populations, people with anaemia or anxiety, and frail older adults prone to fainting.
The challenge is volume. The authors note that a dry mouth (hyposalivation) is a real-life problem in people with catecholamine excess, so they worked to minimize the sample volume needed and make the assay suitable for paediatric and older populations. They say that, to their knowledge, theirs is the first published method validated for metanephrines in saliva samples suitable for newborns and patients with hyposalivation.
What the researchers did
They developed the assay and validated it against current guidelines, checking selectivity, matrix effects, linearity, trueness, repeatability, carry-over and stability. They then tested recovery of the analytes from three collection swabs:
| Swab | Suitable for | Recovery (calibrator levels 2–4) |
|---|---|---|
| SalivaBio infant swab (Salimetrics) | Newborn population | 93–104% |
| Micro•SAL for Children (Oasis Diagnostics) | Newborn population | 90–113% |
| Salivette with synthetic swab (Sarstedt) | Adults only | 85–107% |
Both infant-suitable swabs gave good recoveries, within ±15% for all analytes except one case at the lowest calibration level for 3-methoxytyramine (149% for the SalivaBio swab). The Salivette showed recoveries mostly around 90%, with the lowest below 90% at some concentration levels.
Handling Micro•SAL samples. Saliva collected with Micro•SAL was pressed through a narrow-bore tube into a 2 mL microcentrifuge tube at collection and frozen at −20 °C within 10–90 minutes, then moved to −80 °C for long-term storage. The other swabs were stored on the swab and centrifuged later to release the saliva.
Stability
Metanephrine and normetanephrine showed reduced on-swab stability after 7 days at room temperature, but all analytes were stable at room temperature for 6 hours and tolerated at least one week at −20 °C. In practice this gives a short window for freezing after collection.
What this means for study design
- Match the device to the age group. The study treated two swabs as suitable for newborns and one as adults-only.
- Validate recovery for your analyte. The same assay recovered between 85% and 113% depending on the swab, so the swab is part of the method.
- Plan freezing time. Samples here were frozen within 90 minutes of collection.
- Design for low volume. A 50 µL sample gave the best accuracy, with 20 µL still acceptable.
Collection devices for the youngest participants
- Micro•SAL for Children has a reduced-size collector with a small, soft pad and collects up to 500 µL, with samples comparable to Super•SAL. It is made for younger children who are too old for infant kits.
- Pedia•SAL is a soother-style kit for infants, collecting passively as the child suckles.
Pedia•SAL was not part of this study; it is included as the Oasis infant option.
Sources
- Stressless sampling to improve diagnostics of catecholamine excess: new assay to determine metanephrines in saliva. Endocr Connect. 2025. https://doi.org/10.1530/ec-25-0023