When checking your hormone levels, is a blood test always best?
There are three bodily fluids used for measuring hormone levels: blood, urine, and saliva. Each has certain advantages the others do not offer, and each has disadvantages. From my clinical experience, the different tests serve dif¬ferent purposes, and should be ordered for their usefulness in providing specific informa¬tion rather than as a matter of opinion or merely for convenience of use either for the patient or the doctor.
Use the right test to achieve the best results for the individual patient—that’s my philosophy of practice. Let’s look at the different methods of testing hormones, and see which ones may be best for you.
Hormone Testing in Blood Samples
Though there is no current standard for wellness and anti-aging hormone testing, blood testing is the main method used by most doctors to test hormones. There are several reasons for this. More tests have been performed by blood than by other meth¬ods and therefore, more is known about blood test results. Also, doctors are more familiar with blood testing methods and are more readily able to evaluate the results of most of the hor¬mones from a blood sample than from urine or saliva.
A criticism offered by some doctors and laypeople is that blood tests only provide a snapshot of the total amount of hormone cir¬culating in the bloodstream, and that this does not correlate with levels of the same hormone in the tissues, and therefore does not measure the bioavailability of the hormone. Though this is a valid criticism, it does not answer this question: How does one obtain a tissue specific level of an individual hormone without taking a live sample of that tissue? Of course, this cannot be done, since to take sam¬ples of living tissue from all the main sites of the body such as the liver, lungs, brain, breast, heart, and muscle would be not only extremely painful, but also very expensive and risky.
Though exact tissue bioavailability cannot be accurately measured, the amount of “free” hormones can be measured. Laboratory scientists use a mathematical model to calculate bioavailability based on the level of total hormone, free hormone, percentage of free hormone, and circulating binding proteins that carry hormones in the blood. A free hormone is one that is not bound to carrier proteins.
There are other advantages to blood hormone tests besides their convenience. Blood values are useful in monitoring peak levels of absorption of hormones (when one is on hor¬mone replacement therapies) or the normal metabolic nadir achieved in the natural cyclic secretion of hormones. For example, if you want to see if you are absorbing testosterone from the application of a hormone cream or gel, you can measure your testos¬terone levels two hours after application. The same applies for thyroid medication: measure your thyroid hormone levels after you have taken your thyroid pill to see if it is absorbing sufficiently.
You can also evaluate natural levels of estrogen or progesterone during their monthly peaks, though this does not apply to women past menopause who no longer have a period. Though most hormones are tested for their total circulating level, many hormones can also be tested in blood in their free form.
Blood tests are preferred for estradiol and other estrogens, testosterone and free testosterone, dihydrotestosterone, IGF-I, DHEA-Sulfate, cortisol, and thyroid hor¬mones. A blood sample is also best for the pituitary hormones TSH, LH, and FSH.
Another reason to use blood testing is that health insurances are more likely to cover it, and rarely pay for saliva or urine hormone tests.
24-Hour Urine Hormone Profiles
Hormone testing with urine, in my clinical opinion, does not replace blood testing, though many doctors consider it an equally valuable diagnostic tool for several reasons. It covers a much broader range of hormones, including pro-hormones and hormone metabolites. This provides a more comprehen¬sive hormonal picture. Pro-hormones are the precursors or biochemical building blocks for hormones. Hormone metabolites are the bio¬chemical by-products or end products of hormone metabolism.
The 24-hour period is necessary to collect all of the hormones secreted by your body dur¬ing this time. Since higher amounts of hor¬mones are secreted at different times during the day, this gives a picture of the average level of hormone secretion.
Other useful hormone tests are available using the urine, including different subtypes of estrogens such as 16 alpha (OH) estrone, and urinary metabolites of steroid sex hormones, such as those involved in testosterone and pregnenolone metabolism.
Thierry Hertoghe, M.D., from Belgium and the author of The Hormone Solution, proposes that urinary hor¬mone studies provide the best overall picture of hormone metabolism. He says they are a criti¬cal component for evaluating age-related hor¬monal changes, one that blood studies do not provide, and he suggests a comprehensive 24- hour urinary hormone profile as the initial test to be used in hormone balancing therapy.
I recommend 24-hour urinary profiles for patients aged 35-45, since abnormal hormone values in the blood are rarely found in healthy adults under age 40. It is also valu¬able in people between 45 and 55 years old for fine-tuning their hormone regimen.
There are several disadvantages to urine tests. People with kidney disease do not excrete urine or metabolic products normally, so a urine hormone test is not suitable in these cases. Also, older people are often unable to manage urine collection with accuracy, and for these individuals urine testing may be too cumbersome. Another disadvantage is that this test is complex and difficult to interpret, so you need to consult a physician who is an expert in this type of testing to tell you what it means.
Salivary Hormone Testing
Testing for hormones in a saliva sample is easy and con¬venient. For most purposes, this can be done at home, making it theoretically the ideal method for hormone evaluation. Saliva testing is definitely an alternative to blood or urine testing. Many compounds found in saliva, including hormones, can provide useful clinical information. However, there are drawbacks to salivary hormone testing.
First, not all hormones, such as follicle- stimulating hormone (FSH) or IGF-1 (used as a marker for growth hormone) are offered in salivary tests by all laboratories. There is no common standard among saliva testing laboratories, and many are not FDA approved, meaning that they are not held to the high standards of clinical laboratories. Another disadvantage, especially among older people, is that collecting multiple samples is difficult because of dry mouth due to lack of saliva caused by some prescription drugs or atrophy of salivary glands. This is also true with people who have certain types of autoimmune disorders that cause dry eyes and mouth. Also, most health insurance companies do not reimburse for hormone saliva testing.
One of the most significant technological roadblocks in the development of salivary diagnostics is the low concentration of hormones found in saliva compared to blood (300 to 3,000 times lower than in blood). Hormones are passed from the blood into saliva by a process called ultrafiltration. For molecules to squeeze through by this process, they have to be very small. Because the levels are so tiny, this makes the reference ranges in salivary samples difficult to interpret for their clinical significance. Third, contamination by blood, as from bleeding gums, even in invisible amounts, is common in saliva testing. This results in higher values than expected because of the added blood hor¬mones introduced in the saliva. Since there is no easy way to adjust for this kind of contami¬nation, the results must be discarded and another sample taken.
There are advantages to salivary testing. Saliva is a good way of testing because its collection is noninvasive and the donation process is relatively stress free, so even multiple collections can be obtained without imposing too much discomfort on the donor. Saliva is easy to collect, store, and transport; it does not require highly trained personnel. In addition, saliva is a “real-time” fluid because the salivary glands are exocrine glands that produce profiles indicative of an individual’s health and well-being status at the moment of collection. Hormones secreted at different times during the day, such as cortisol and melatonin, can be measured using multiple samples collected throughout the day and night, allowing for a representation of the normal (or deviation from) cyclical pattern in real time.
Another advantage of salivary testing is that it measures the free or bioavailable hormone fractions of the total amount of hormone; “free” means that the hormone is unbound by bind¬ing proteins in the blood such as sex hormone binding globulin. Though not the same as specific tissue levels, salivary levels offer an approx¬imation of how much hor¬mone is available to enter the tissues. However, relying exclusively on salivary hormone testing, despite obvious advantages in collection, can be clinically misleading.
In my practice, after testing thousands of patients, I still prefer blood tests for hormones. I use urine tests to check specific forms of estrogen that cannot be tested in blood or saliva, and to assess markers for bone loss, as well as for neurotransmitter levels. I find that saliva tests are best used to follow up those using topical hormone creams, and for serial testing as when following hormone levels through the monthly menstrual cycle. Saliva is the test of choice for free DHEA, free cortisol, and melatonin, when testing hormone rhythms over a 24-hour period of time.
The clinical bottom line is that blood, urine, and saliva tests each have advantages and disadvantages. One test type doesn’t replace the rest, but adds information that can be part of an assessment for the best outcome for the individual patient. What I want for my patients, and that I recommend you should require of your doctor, is the test with the highest level of accuracy and the greatest clinical value for your health concerns.