When testing hormones like cortisol, DHEA, testosterone, estrogen, or progesterone, it’s important to know that saliva and blood tests measure different forms of these hormones — and their values should not be directly compared or converted.
Saliva tests measure the free (bioavailable) hormone — the fraction that is active and available for use by the body.
Blood tests (serum or plasma) typically measure the total hormone level — this includes both the active (free) portion and the inactive (protein-bound) portion.
Since the amount of free hormone is only a small part of the total, a value from a saliva test will naturally be much lower than a blood test result, and they’re expressed in different units.
Different testing methods = different sensitivity
Different testing methods = different sensitivity
Saliva samples are typically analyzed using methods optimized for very small hormone concentrations (e.g., pg/mL or pmol/L).
Blood samples, on the other hand, are suited for detecting higher concentrations and use units like ng/mL or nmol/L.
No direct conversion is possible
Because saliva and blood tests measure different biological components using different technologies, there is no reliable formula to convert results between them.
That’s why each test uses units specific to its method to ensure results are meaningful and accurate.
We always present your results in the most relevant unit for the method used, along with a reference range that allows you to interpret the result correctly.
The best way to understand your hormone levels is to compare your value to the reference range provided in the report, rather than trying to match it to blood test results from another source.
Summary: Saliva and blood tests measure different things, with different sensitivity and purposes. This is why they require different units to provide correct and useful results.
Comparing Mineral and Vitamin Tests (Whole Blood vs. Serum/Plasma)
Just like with hormone testing, measurements for minerals and vitamins depend on the sample type used. Whole blood tests measure the total amount inside both red blood cells and plasma, while serum or plasma tests measure only what circulates in the fluid portion.
Because of this, values and reference ranges cannot be directly compared or converted. Whole blood results are often higher since they include minerals stored inside cells.
For example, zinc, magnesium, and selenium are much higher in whole blood than in serum. A zinc value of 6.5 mg/L from a whole blood test might seem high compared to serum ranges (0.7–1.2 mg/L), but they reflect different measurements.
Always interpret results using the reference range provided for that specific test type.