There are questions whether blood draw using needles is always necessary for a health test.
In some cases, a saliva sample can be a non-invasive and stress free alternative while providing equivalent high quality results.
A testosterone test using saliva sample is good example.
Saliva samples provide clear advantages over blood whenever an analysis using saliva is possible. They can be collected at home and sent to the lab without requiring the patient to visit the clinic or lab. This is especially important for tests requiring multiple samples throughout the day or on a regular basis.
Most children, and a significant adult population, are afraid of venipuncture. The sudden adrenal spike as a response to the stress of blood collection can interfere with the results. Saliva sample collection is obviously better choice in cases where a blood draw is almost impossible. For example, in athletes during training or in aged patients with thin veins,
The main concern regarding a saliva based test is the variation in results, either from the labs or the way samples are collected.
There are possible ways to close these concerns.
Labs that test thousands of human samples, regularly compare their results with their peers, and monitor the trends of their most frequent patients are highly reliable due to close control of the variations. In order to maintain their quality, the labs are required to be CLIA-certified every two years. CDC, in partnership with CMS and FDA supports the CLIA program and clinical laboratory quality.
Another key sources of variations in results is the time of the day for saliva samples collection. Testosterone levels are highest in the morning and then decline during the day. That’s why one should collect a saliva sample early morning within 30 minutes of waking up, without brushing your teeth, or eating and chewing.
Carefully collecting the samples with strict guidelines can avoid the variations in results and provide a very narrow range of reference against which each test can be compared.
There is credible research published, as an example in Clinical Chemistry, a journal by The American Association for Clinical Chemistry showing that saliva based health testing has proven to be reliable and, in some cases, even superior to other body fluids.
Because saliva testing has evolved in last few decades, the old school of testing by blood still tends to keep faith in their old methods. That should not force patients to go through the painful experience of a blood draw, especially for kids and those with fear of needles.
There is a note of caution though. Clinical interpretation of the results is a challenge. The tests are good first step to confirm or overrule the cause of symptoms at a rather inexpensive and expedited way. But a thorough follow up should always be part of the full diagnosis.