There is now sufficient evidence to show that standard serum (blood) testing protocols cannot quantify low concentrations of hormones in a reliable way. In general, blood measurements only give the total saliva hormone concentration, whereas saliva testing measures the important free, bioavailable, hormone level. “The measurement of testosterone (T) in plasma or serum, as done in most laboratories, suffers from a number of serious problems.” – Endocrine Society Position Statement 
A cursory look at Serum & Saliva Hormone Testing
Research has shown that, for most purposes involving otherwise healthy individuals, this method [serum] has limited application. Here’s why:
Saliva hormones present in the blood are either completely “bound” to their specific binding globulins, or “free”. At present most saliva hormone testing is conducted using the traditional method, i.e., by sampling and analysing blood – an invasive and costly procedure.
The bound component is biologically inactive and is considered to be a kind of hormone storage. Only less than 5% of the total hormones present are “free”, “active” or “bioavailable” and these are responsible for hormone activity in the body. In serum (blood) or plasma testing, the saliva measurement represents the level of the total hormone, including the “bound” component. This total concentration at best gives only an approximate indication of the bioavailable hormone present in cases of completely healthy and normal patients.
Disclaimer: TestoChecker provide Saliva hormone test kits in Australia and willingly disclose it’s interest in the popularity of saliva hormone testing. It should also be noted that Serum, Saliva, Hair as tissue sample types all have unique advantages, and likewise, none test specimen type can be considered perfect. Read our Blog Post ‘Limitations of Serum AND Saliva for Testing Hormones‘ if you’re interested to read more about this.
The Endocrine Society published an official position statement , including that reliable measurements in serum testing either need an additional extraction step, or need to be completed using chromatographic methods, such as tandem MS or GCMS (sophisticated and very expensive equipment). This casts doubt on the validity of blood testing for free, bioavailable hormones.
Hormones tested reliably
On the other hand, saliva sampling is non-invasive and can be done anytime, anywhere at multiple time points day or overnight. Provided the proper collection and testing procedure(s) is observed, hormones tested reliably using saliva as the biological specimen type include:
- Estrone [E1]
- Estradiol [E2]
- Estriol [E3]
Adrenal Function Extended Profile Test Kit
Comprehensive Cortisol Test Kit
Female Full Hormone Profile w/ Oestrone (E1) BioHealth
Fertility Balance G2 Hormone Test
Melatonin Sleep Rhythm Test Kit