How to Interpret the Numbers on Saliva Hormone Tests

By John R. Lee, M.D.
From the John R. Lee, M.D. Medical Letter – January 2000

Editor’s Note: Dr. Lee wrote this article because he knew that his readers use a variety of different laboratories for testing their hormones in saliva. Sadly, that sometimes makes it hard to understand saliva test results, as different laboratories report their results using different units of measurement for the same hormones.

Over the years, we have sold the saliva tests of a single laboratory — ZRT Laboratory — that consistently reports its saliva test results using the same unit of measurement for the sex hormones (picograms per milliliter, or pg/ml), and the same unit of measurement for the adrenal hormones (nanograms per milliliter, or ng/ml). This makes it much easier for our customers to understand their test results. In addition, all ZRT Laboratory test results include excellent written interpretations written by doctors on staff. This empowers you to understand your test results, make informed decisions with your doctor about balancing your hormones, and take action to balance them.

If you want to take a ZRT Laboratory saliva hormone test, we encourage you to order them from us! We offer ZRT Laboratory tests to customers in the United States at a significant discount from their list prices. Click here to learn more about and our ZRT Laboratory saliva hormone tests and to order them.

A Little Math Will Solve the Problem

Every week I get requests from people to help them interpret their saliva hormone test results. One major problem is that different labs use different units of measurement to record hormone levels.

Generally, the balance between progesterone and estradiol during the luteal (mid-cycle) phase in healthy premenopausal women is in the neighborhood of 300 to 1. That is, in healthy young ovulating women, the saliva concentration of progesterone is around 300 times higher than estradiol during their luteal phase. (We have reported this ratio as 200 to 1 in the past, but time and experience have shown us that 300 is a more useful ratio.) Having this ratio is useful because there is such a wide range of “normal” levels of estrogen and progesterone in healthy women. To make the ratio properly, it is important to use the same units of measurement to report the concentrations.

It’s Like Comparing Apples and Oranges but It’s Picograms and Nanograms

For example, if box A weighs 10 kg, and box B weighs 20 kg, it is clear that box B is twice as heavy as box A.

However, if the weight of box A is reported to be 22 lbs, while box B is reported as 20 kg, then one might mistakenly think that box A is heavier. This is like comparing apples with oranges. To make the proper ratio, the weights must be translated into the same unit of measurement: Since one kg equals 2.2 lbs, the 22-lb box A actually weighs only 10 kgs.

Similarly, to compare the concentration of progesterone to estradiol, it is important that they be expressed in the same units of measurement. The problem is that different labs report the concentrations of different hormones in different dimensional units. One lab makes it easy by reporting both estradiol and progesterone in picograms per milliliter (pg/ml). For example, progesterone concentration may be 600 pg/ml and estradiol concentration 2.0 pg/ml. The ratio of progesterone to estradiol is simple: 300 to 1.

[Editor’s Note: The lab Dr. Lee refers to above is ZRT Laboratory, and we sell ZRT Laboratory saliva test kits on this site. One reason we do so is because the test results use the same units of measurement, making the results easier to understand. Click here to learn more about and our ZRT Laboratory saliva hormone tests and to order them.]

Another lab, however, confuses people because it reports estradiol concentration in pg/ml, but reports progesterone concentration in nanograms per milliliter (ng/ml). The same concentrations as in the example above would be recorded as progesterone 0.6 ng/ml and estradiol 2.0 pg/ml. If the reader did not spot the difference in dimensional units and did not know that 1 nanogram equals 1000 picograms, she might think that her progesterone is far too low.

Here’s Where the Math Comes In

To determine the actual ratio, you must multiply the progesterone reported in ng/ml by 1000 to put it into pg/ml. When this is done, it is obvious that the progesterone concentration of 600 is 300 times greater than the estradiol concentration of 2.0.

This indicates that the ratio of progesterone to estradiol is fine. Assuming that your saliva test levels fall within “normal” ranges, you can probably assume that your symptoms are due to something besides an imbalance of those two hormones.

Yet another lab reports its results in millimoles per liter. Even college chemistry students would have trouble interpreting this unit of measurement. Fortunately, the lab also reports the concentration in pg/ml or ng/ml.

Timing the Testing

If a premenopausal woman is taking the hormone test, the best time of the menstrual month for obtaining hormone concentrations is 5 to 6 days after presumed ovulation. Ovulation is most often around day 12 to 14 of the cycle. Many women around age 35 will ovulate, but the corpus luteum makes progesterone for only a day or so, leaving them estrogen dominant and progesterone deficient for the rest of the month. Ideally hormones should be tested every 2 to 3 days throughout the luteal phase, but this is expensive. Testing once 5 to 6 days after presumed ovulation is usually adequate to reveal any problems. However, women who are having problems with fertility or miscarriages might want to spend the money to test every two to three days.