Is saliva testing accurate? In some cases, e.g., for cortisol and hormones testing, saliva is very popular and as accurate as a blood test. Learn more about the advantages of using saliva for your next lab test.
People often wonder why they have to go through the painful process of drawing blood and not simply use saliva or a swab for their lab tests.
Unfortunately, most lab tests have been developed with blood samples. But in past few years, saliva has shown to be favored method for many markers.
In some cases, a saliva sample can be an easy stress-free alternative with same high quality of results. Cortisol stress hormone test and men's and women's hormones are good examples.
Saliva has clear advantages over blood during collection whenever it's possible to test with a saliva sample.
Saliva can be collected at home and sent to the lab without requiring you to visit the clinic or lab. This is especially important for tests that need many samples throughout the day or on a regular basis. Also, you don't need a nurse, phlebotomist or a trained medical professional to collect saliva as long as you follow the instructions carefully. Here are a few more benefits:
Children and many adults are afraid of needles. This fear and stress during venipuncture may cause a sudden adrenal spike which can interfere with the results.
Saliva samples are stable at room temperature for several days (e.g., our hormone test saliva samples are stable for 30 days); when frozen, they can be stored for months.
Saliva can be collected in natural environment that reflects normal routine; blood is often collected in different settings e.g., in a lab or clinic at certain hours.
Saliva sample collection is obviously better choice in cases where a blood draw is almost impossible. For example, athletes when they are training or seniors who have thin veins or sample collected at night before or after sleeping.
Some of the main complaints about saliva collection include social taboo associated with spitting and not being able to produce enough sample.
Here are few things you can do to help in collection:
Try to relax, in a private, comfortable space. A stressful situation might cause unwanted increase in stress hormone levels.
Rinse your mouth 10-15 minutes before collection.
Imagine your favorite food to help the mouth release more saliva.
Sometimes, smelling a lime or lemon helps. It's best to NOT lick or drink citrus as that might change the pH of saliva.
It may take 5-10 minutes to collect the desired amount, which is okay. But make sure to fill the tube up to three-fourth of the volume (not including the bubbles).
Do not drink alcohol 12-24 hours before collection. Alcohol may not be fully out of your system in this much time.
Avoid any exercise for at least 30-60 minutes before collection. This may affect your results as some hormones (e.g., testosterone and cortisol) are known to increase with exercise.
Do not brush teeth for at least 30 minutes prior to collection. Blood from gums might contaminate the sample.
Do not smoke, drink caffeine, diary or sugary drinks 30 minutes before collection. They tend to change the pH of the mouth and interfere with natural saliva production.
Avoid eating at least 60 minutes before collection. Food particulates might contaminate the sample.
Specify any supplements or medicines you are taking. Anti-depressants, anti-psychotics, and stimulants can affect your results.
Certain hormones also depend on menstrual cycle. For example, when testing for a Women's Health Test, that checks progesterone levels, samples should be collected on day 19 to 21 of the menstrual cycle (day 1 will be the first day of bleeding).
It's best to maintain a normal routine. Jet leg, night shift work, and certain medicines can interfere with saliva test results.
Either wait until you are back to normal routine, or clearly specify them on the form to ensure the lab is aware of your condition.
Melatonin or sleep hormone is highly dependent on the time of the night and other factors such as computer screens or supplements.
Role of uneven sleep routine is one of the most commonly asked questions.
If you tend to wake up in middle of night or early, or can't go to sleep easily, consider collecting your sample after the longest stretch of sleep. This is especially important for cortisol and testosterone, that rise soon after waking up and depend on the time of collection.
Not all tests can be performed with saliva because a corresponding marker of a blood test may not be available in saliva. For example, to check total testosterone, where 98% of testosterone is bound to SHBG (sex hormone binding globulin) can only be tested with blood. But the remaining 2% free testosterone can be checked with saliva and acts as a proxy for the total volume.
One of the main concerns 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 monitors 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 and cortisol 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 their teeth, or eating and chewing.
Carefully collecting the samples with strict guidelines can avoid possible variations in results.
There is credible research published, e.g., by The American Association for Clinical Chemistry, showing that saliva-based tests have proven to be reliable and, in some cases, even superior to other body fluids samples.
A study of 197 samples comparing free saliva cortisol and total blood serum cortisol had strong correlation. It recommended saliva as a credible option due to ease of use.
Because saliva testing has evolved in last few decades, the old school of blood based testing 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 saliva results is a challenge because not all doctors may have experience with saliva testing. 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.
Order a 24-hour cortisol test.
Current Status of Salivary Hormone Analysis: Clinical Chemistry, Vol 54(11), Nov 2008.
Cortisol in Saliva - Reference Ranges and Relation to Cortisol in Serum, by Aardal and Holm, Eur J Clin Chem Clin Biochem, 1995.
All About Cortisol - a brief summary of the stress hormone.
Cortisol: Risk Factors - key facts and the risks related to high cortisol levels.
Five Telltale Signs of High Cortisol Levels - learn about the common signs.
Why Morning Cortisol and its Collection Time are so Important? - learn why morning levels are crucial.
The Most Common Effects of High Cortisol Levels - know what chronic high stress can do to you.
How Can My Medicine Affect Cortisol Levels? - a list of common drugs that can interfere with your results.
All About Testosterone - a comprehensive review of the male hormone.