Hormone Substitution Vs. Hormone Replacement
The time has come to recognize the clear difference between these two terms. It isn’t just a question of semantics. There is increasingly strong evidence that they represent two entirely different approaches, the former being superior to the latter both in clinical benefits and safety.
While “hormone replacement” can refer to any hormones, it is generally reserved to mean estrogen and progesterone use in perimenopausal and postmenopausal women.
But in order to be “real hormone replacement”, it must replace the hormones which the ovaries no longer are producing, estradiol and progesterone, in kind and in adequate amounts. Furthermore, these hormones must be identical in structure to those they replace, and mimic their route of entry directly into the systemic blood stream, rather than through the intestinal wall and the liver as occurs with oral (by mouth) administration. Otherwise, what is being done is hormone substitution, not replacement.
Why is this important? First and foremost, virtually all major studies to date have been done using hormone substitution. The results of these studies are not only questionable; they are completely misleading, and in some instances totally contradict the true situation. Premarin, the type of estrogen used in almost all studies so far, is a mixture of horse estrogens (primarily equilin) derived from the urine of pregnant horses.
It cannot be measured accurately in human blood, so its effects cannot be quantitated and dosages compared. Provera (and a mixture called Prempro, which is Premarin plus Provera), is a synthetic progesterone-like drug which again cannot be quantified in human blood samples and produces several effects entirely different from real human progesterone. Both are taken by mouth (orally).
Some health benefits from Premarin and human ovarian estradiol is similar – for example, protection against osteoporosis and colon cancer. Some are entirely different.
Memory, mood, cognition, and sleep are favorably affected by non-oral estradiol, but much less so by Premarin. Other effects which can be dangerous are caused by Premarin, such as cardiovascular risks (heart attacks, strokes, blood clots, phlebitis), gall bladder disease, elevated blood pressure, and elevated C-Reactive protein, but are not caused by non-oral estradiol (creams, patches, subcutaneous pellets).
Likewise, Provera seems from two recent studies to increase the risk of breast cancer. So far, no studies using real human progesterone suggest that it does the same, although no long term studies are yet available, since protocols using non-oral progesterone itself are so far of too short duration. No studies have indicated any favorable features that Provera has in comparison to real progesterone.
The time has come for a definitive study comparing benefits and risks using nonoral human estradiol and progesterone for hormone replacement rather than more studies involving hormone substitution. The consequences, good and bad, are too important to too many women to delay or ignore.