Progesterone is a steroid hormone produced by the adrenal gland in both men and women, the testes in men and the ovary in women. It plays a role in the female menstrual cycle and pregnancy and circulates throughout the body binding to receptors in the brain, the cardiovascular tissue, breast tissue and more. Progesterone is also a precursor to other important hormones in our body- cortisol, aldosterone, testosterone and estradiol.
Progestins are a synthetic progestogens that bind some progesterone receptors in the body, but not all. They were produced first in 1938 in hopes of finding a patentable drug that could work like progesterone in the body. While chemically similar to progesterone, they are not identical, and this makes them patentable.
Since Progestins and Progesterone are different molecules they have different effects on the body. As a general rule, synthetic progestins are more potent that bio-identical progesterone. They have a longer half life than progesterone, have greater relative binding affinities and have been found to have a stronger affect on the endometrium at lower doses than progesterone. Thus -more potent. Progestins also can have androgenic qualities like increased facial hair growth while progesterone can be used as a treatment to reduce this symptom.
The metabolism of these two hormones differs quite a bit. Metabolites of progesterone are well known and include dihydroprogesterone, pregnenolone, pregnanediol and their isomers. Progesterone metabolites can be found in feces, urine, saliva and blood. Less is known, however, about the metabolism of progestins. One thing we do know is that progestin metabolites while fewer in number, have biologic activity themselves. Norethindrone in fact metabolizes to ethinyl estradiol increasing that total amount of ee that an individual is exposed to in combined HRT.
It's a very common mistake among health care professionals to use the terms progesterone and progestin interchangeably. But this mistake can be deadly. We know now that progestins have an unfavorable effect on the cardiovascular system while progesterone can be used to treat and prevent cardiovascular disease. A great review of this can be found in the Hermsemeyer et al article "Cardiovascular effects of medroxyprogesterone acetate and progesterone: a case of mistaken identity?"
Progesterone protects against estrogen-induced breast cancer, as seen in the following study in the http://aje.oxfordjournals.org/cgi/content/short/114/2/209 and as outlined in Dr John Lee, David Zava and Virginia Hopkins book "what your doctor may not tell you about breast cancer". Synthetic progestins when combined with estrogen increase a woman's risk of breast cancer. Recent studies can be seen at these links http://content.nejm.org/cgi/content/abstract/332/24/1589 http://jama.ama-assn.org/cgi/content/abstract/283/4/485
So if progestins can increase our risk for cardiovascular disease and breast cancer, while progesterone prevents them, if they each have their own distinct chemical structure, if they are metabolized differently and affect our other hormones in two different ways- how can we refer to them interchangeably? They are clearly affecting our health and our bodies in different ways. They are different!
We certainly don't know everything there is to know about these two hormones yet. There is always more to learn. Current evidence suggests that using progesterone is a safer and more beneficial choice than progestins and naturally, it make sense that we might want to use a molecule that our own body makes. But what's most important as health care providers, as researchers and health educators is that we come to understand that there is a distinct difference between Progesterone and Progestins and call it like it is!
Progestins are a synthetic progestogens that bind some progesterone receptors in the body, but not all. They were produced first in 1938 in hopes of finding a patentable drug that could work like progesterone in the body. While chemically similar to progesterone, they are not identical, and this makes them patentable.
Since Progestins and Progesterone are different molecules they have different effects on the body. As a general rule, synthetic progestins are more potent that bio-identical progesterone. They have a longer half life than progesterone, have greater relative binding affinities and have been found to have a stronger affect on the endometrium at lower doses than progesterone. Thus -more potent. Progestins also can have androgenic qualities like increased facial hair growth while progesterone can be used as a treatment to reduce this symptom.
The metabolism of these two hormones differs quite a bit. Metabolites of progesterone are well known and include dihydroprogesterone, pregnenolone, pregnanediol and their isomers. Progesterone metabolites can be found in feces, urine, saliva and blood. Less is known, however, about the metabolism of progestins. One thing we do know is that progestin metabolites while fewer in number, have biologic activity themselves. Norethindrone in fact metabolizes to ethinyl estradiol increasing that total amount of ee that an individual is exposed to in combined HRT.
It's a very common mistake among health care professionals to use the terms progesterone and progestin interchangeably. But this mistake can be deadly. We know now that progestins have an unfavorable effect on the cardiovascular system while progesterone can be used to treat and prevent cardiovascular disease. A great review of this can be found in the Hermsemeyer et al article "Cardiovascular effects of medroxyprogesterone acetate and progesterone: a case of mistaken identity?"
Progesterone protects against estrogen-induced breast cancer, as seen in the following study in the http://aje.oxfordjournals.org/cgi/content/short/114/2/209 and as outlined in Dr John Lee, David Zava and Virginia Hopkins book "what your doctor may not tell you about breast cancer". Synthetic progestins when combined with estrogen increase a woman's risk of breast cancer. Recent studies can be seen at these links http://content.nejm.org/cgi/content/abstract/332/24/1589 http://jama.ama-assn.org/cgi/content/abstract/283/4/485
So if progestins can increase our risk for cardiovascular disease and breast cancer, while progesterone prevents them, if they each have their own distinct chemical structure, if they are metabolized differently and affect our other hormones in two different ways- how can we refer to them interchangeably? They are clearly affecting our health and our bodies in different ways. They are different!
We certainly don't know everything there is to know about these two hormones yet. There is always more to learn. Current evidence suggests that using progesterone is a safer and more beneficial choice than progestins and naturally, it make sense that we might want to use a molecule that our own body makes. But what's most important as health care providers, as researchers and health educators is that we come to understand that there is a distinct difference between Progesterone and Progestins and call it like it is!
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