Salivary testosterone testing measures hormone levels using a sample of spit, offering a less invasive alternative to traditional blood draws. This approach has gained popularity, especially with the rise of convenient at-home collection kits. These tests screen for potential hormonal imbalances by providing a snapshot of the body’s androgen status. Understanding the results requires examining the scientific consensus regarding its accuracy and the specific type of hormone it measures.
Understanding What Saliva Tests Measure
Testosterone circulates in the bloodstream in two main forms: bound and unbound. The majority (approximately 97% to 98%) is bound to proteins like sex hormone-binding globulin (SHBG) and albumin, making this bound portion largely inactive. The remaining small fraction is the unbound, or biologically active, hormone.
This active portion is the only form that can passively diffuse from the blood into the saliva. Consequently, salivary tests measure this free, bioavailable testosterone, which directly interacts with tissues and exerts its effects. Measuring only the free portion is an advantage because it provides a direct index of the hormone available for use by the body’s cells. Unlike blood tests for total testosterone, which are influenced by SHBG levels, salivary testing offers a measurement independent of these binding proteins.
Quantifying Test Reliability
The reliability of salivary testing is assessed by comparing its results to established clinical methods, primarily serum free testosterone. Scientific literature indicates a moderate to strong correlation between salivary and blood free testosterone levels, particularly in men. Studies often report correlation coefficients ranging from 0.70 to over 0.90 in male populations, supporting its use as a reliable surrogate for the biologically active hormone.
Modern, highly sensitive laboratory techniques, such as liquid chromatography-tandem mass spectrometry (LC-MS/MS), have improved analytical precision. Using these advanced methods, the test can detect the low concentrations found in women and children. The consistency of the measurement, known as precision, is also high. Laboratory studies demonstrate good reproducibility, with intra-assay variations often below 5%. This consistency is valuable for monitoring changes over time, such as natural daily fluctuations.
However, the correlation between salivary and serum free testosterone is weaker and more variable in women compared to men, sometimes reporting coefficients below 0.50. This is attributed to the significantly lower hormone concentrations present in female saliva. While saliva testing tracks cyclical changes well, its accuracy for establishing an absolute diagnostic baseline can vary between laboratories and methodologies.
Common Variables That Skew Results
The accuracy of a salivary testosterone test is highly dependent on proper collection technique, as several extrinsic factors can artificially skew the results.
Diurnal Rhythm
Testosterone follows a distinct diurnal rhythm, naturally peaking in the morning, typically between 7:00 a.m. and 9:00 a.m., and declining throughout the day. Collecting a sample outside of this peak window without accounting for the time of day can lead to a misleadingly low result.
Oral Contamination
Recent oral activities can compromise the sample integrity. Eating, drinking, or chewing gum within an hour before collection can dilute the sample or introduce substances that interfere with the assay. Similarly, brushing teeth too close to the collection time, often within two hours, can cause minor gum irritation.
Blood Contamination
Even a minute amount of blood from irritated gums can contaminate the saliva sample. Since testosterone concentrations in the blood are vastly higher than in the saliva, this small amount of blood contamination can artificially and significantly inflate the measured hormone level. To ensure a valid test, it is recommended to avoid dental work for 48 hours and use the passive drool technique, which minimizes oral stimulation.
Saliva Testing Versus Serum Testing
Serum (blood) testing remains the clinical standard for the initial diagnosis of many androgen-related conditions. A blood test typically measures total testosterone, providing the overall amount of the hormone in circulation, which is the measurement most widely accepted in medical guidelines. Serum collection is invasive, requiring a venipuncture, and can be challenging for frequent sampling.
Saliva testing, by contrast, is non-invasive and easy to perform repeatedly at home, making it useful for monitoring hormone fluctuations. Because saliva reflects the free, biologically active portion, it is a preferred method for tracking the effectiveness of hormone replacement therapies or observing diurnal patterns.
A healthcare provider may use a serum test for an initial diagnosis to establish a definitive baseline of total testosterone. Conversely, they might recommend salivary testing for subsequent monitoring, especially when symptoms correlate better with the bioavailable hormone level. Both methods offer distinct but valuable perspectives on an individual’s hormone status.