In fact, the entire picture needs to be evaluated in terms of the proper ratio of the two rather than the two hormones, isolated, considered at their individual levels. While you can get into lots of complexities measuring the two values and calculating their ratios (Dr. Joseph Collins goes into this at length in his book, What's Your Menopause Type, if you really want to pursue doing it), the bottom line is that the balance needs to be even, with one counteracting the worst of the other and not inhibiting the best of it.
This does not mean taking the same dose of each or even supplementing with both hormones—as we said back in the discussion of dosing, numbers don't mean anything except relative to that one particular brand/form/hormone. Instead, it means looking at both hormones such that they reach a balanced effect in your particular body. Finding this is an experiential, not mathematic, process, so we don't feel it's especially useful to get too hung up trying to work out the numbers. Listen to your body carefully, and that will tell you what you want to know.
Low progesterone
In particular, the excitatory effects of estrogen call out for progesterone's soothing counterbalance. Insomnia, jitteriness, anxiety—all of these may be well addressed by progesterone when they cannot be addressed by estrogen reduction alone. Mental fuzziness or moodiness are also things that could be helped by the addition of progesterone if estrogen alone has not cleared things up.
Libido and genitourinary health are also areas where adding progesterone can have notable effects. Remember, estrogen in excess inhibits orgasm, but progesterone can help you produce the additional testosterone needed to experience desire once your estrogen is as fully tuned as it can be. Incontinence and vaginal dryness are also signs that progesterone may be of help if estrogen alone has not resolved the problem. There are lots of progesterone receptors in this part of the body.
Fluid retention and painful breasts can be helped by increasing progesterone although if they are caused by excess estrogen, adjusting estrogen downward is is a much better way to begin dealing with them. Progesterone counterbalances estrogen's effect on appetite (and insulin metabolism), and becoming better balanced on the two may help limit the weight gain that estrogen may seem to cause.
Muscle aches and joint pains may indicate a low progesterone level relative to estrogen.
Dry skin or eyes can also reflect this sort of imbalance.
Attentiveness to progesterone adequacy can be very helpful when fibrocystic breasts are aggravated by estrogen, to an extent that some claim it "cures" fibrocystic breasts (we wouldn't go that far, but it does make a difference for many).
High progesterone
Progesterone has a soothing effect on the nerves and brain, and this taken to extremes is what is most often seen at excess. Drowsiness is often the first sign noted. To some extent, this may be an inevitable result of progesterone use. For this reason, many women take their progesterone at night. Oral forms of progesterone are particularly sleep-inducing in the way they are metabolized, so they should not be taken in the morning.
Other symptoms of progesterone excess that go beyond sleepiness are depression, apathy, and even suicidal ideation. These are not truly side effects, or signs of being intolerant of progesterone, as some critics of progesterone use have suggested. Rather, they are the normal effects of this hormone when it's present in significant excess related to needs.
Some women report that when they first begin taking progesterone, they experience dizziness and vertigo. This may be related to the fact that progesterone acts on some of the same parts of the brain and in a similar way to anesthesia. If this represents a symptom of excess, it seems to be a transitory one that clears as your system accommodates to a greater availability of the hormone. It can, in the short term, however, represent a significant safety hazard requiring some vigilance to avoid putting yourself, or others, at risk.
One mysterious (that means we don't know the physiologic basis for it happening) effect in the progesterone "intolerant" is bladder problems. Some women have either a great increase in urinary tract infections or a feeling like having an infection as soon as they try taking a "normal" progesterone dose. Since interstitial cystitis is believed to have a hormonal link, we're sure this is all tied in together somewhere—we just aren't quite sure of exactly how. What you need to know is that yes, if these symptoms start and stop with starting/stopping progesterone, they may be related to your personal level of needs. If it happens to you, you may want to get some serious lab work to determine whether you need progesterone at all, and if you do, work with exquisitely tiny doses to feel your way along.
As we've said throughout this guide, everyone's need for hormones is different. Some women respond to even very low doses of progesterone with symptoms of excess. But that's not so much an excessive susceptibility as an indication that for these women their endogenous production is adequate to provide for their needs. In practice, the range of progesterone tolerance (the difference between meeting needs and excess) can be quite narrow, and a tiny dose—or none at all—could be all that is needed to complete balance between the estrogen you're taking and the progesterone you're making if any supplementation is needed at all. Our hormones are supplements to what we are making, meant to bridge the gap between what we make and what we need; they are not something we must either take or have none at all of, even when we no longer have ovaries.