Blood, Urine, and Saliva: which one is best for measuring hormones?
Serum (blood), urine, and saliva testing are all useful tools for measuring hormones, but they all have areas that they shine in and areas that they fall short in. Oftentimes a combination of these three methods is necessary to get the best understanding of what your hormones are doing. Read on to understand the when and why of each form of hormone testing.
Blood testing: Also known as serum testing
Serum testing doesn’t differentiate between bound and unbound (free) hormones. The unbound hormones are the hormones that are available for use by the body so these are the shormone levels that we are most about. However, because serum can't differentiate between bound and unbound it can seem like hormone levels are falling into the normal or even high range due to the amount of bound hormones showing up in the lab results. What this means is that your hormone levels can show up within range but you are actually functionally deficient and can have symptoms because of it.
Serum testing doesn’t differentiate between bound and unbound (free) sex hormones. The unbound hormones are the hormones that are available for use by the body so these are the shormone levels that we care most about. However, because serum can't differentiate between bound and unbound it can seem like hormone levels are falling into the normal or even high range due to the amount of bound hormones showing up in the lab results. What this means is that your hormone levels can show up within range but you are actually functionally deficient and can have symptoms because of it. Serum testosterone is the exception in that it's levels can be measured as both total and free Testosterone which can be useful.
Also, hormones are pulsatile in nature, meaning they fluctuate throughout the day and night. Because blood draws are only done once, they only give you a single snapshot of what your hormones are doing as opposed to a clear picture of how they are fluctuating throughout the day.
Serum is best for measuring thyroid hormones, LH, FSH, prolactin, fasting insulin, and sex hormone binding globulin (SHBG).
Saliva testing:
Saliva measures free, unbound bioavailable hormones but bound hormones do not pass into the saliva.
Saliva testing is usually done as multiple collections throughout the day and is a noninvasive method that is done at home. Saliva is most commonly used for insight into your cortisol activity. Cortisol is another hormone that is diurnal, meaning it fluctuates throughout the day so the multiple test times give useful insight. There are restrictions on eating and drinking times when you're doing saliva testing though which can feel inconvenient.
Saliva testing is not used for measuring thyroid hormones.
Urine testing:
Urine testing measures both the parent hormones and the metabolites of the hormones meaning what the hormones are broken down into before they are excreted. This is advantageous because the metabolites of hormones can give more insight as to what is going on inside of the body. For example, estrogen is broken down into different metabolites, some of which have protective effects and some of which have carcinogenic effects .
I use the DUTCH test for urine testing because it is done at home, making it noninvasive and convenient. It also doesn’t involve carrying around a pee jug like traditional urine testing does which can be very cumbersome.
Urine testing collects a large amount of information including both sex and adrenal hormones like DHEA and cortisol, and also looks at their metabolites, aka how your body is breaking down the hormones.
Urine testing is not available for thyroid hormones.
Serum, saliva, and urine testing can all offer valuable insight as to what's going on in your body. Talk to your doctor to determine what's the best combination of testing for you.