That is an interesting question and comes up at almost every hormone seminar I attend. The audience at these conferences is very diverse with healthcare providers from many different specialties. These specialties include OB/GYN, Cardiology, Endocrinology, Orthopedics and many more. It is widely assumed that women who have had a hysterectomy don’t need to take progestogen. This seems to be especially true among the OB/GYN and Endocrinologist. If you do a google search you will see many of articles from the well respected Cleveland Clinic and Mayo Clinic that clearly state, if you have had a hysterectomy and no longer have a uterus, you don’t need to take progesterone. That belief is totally wrong. Let me be clear, you do need progesterone even if you don’t have a uterus.
The notion that women no longer need progesterone after hysterectomy comes from the proven fact that if you take Estrogen replacement therapy you must take Progesterone to prevent endometrial cancer. It is a scientific fact that taking Estrogen without Progesterone can cause cancer of the uterus. Therefore, if you don’t have a uterus, you can not get endometrial cancer and therefore don’t need Progesterone. This misconception assumes that the uterus is the only tissue in the body that has Progesterone receptors. This assumption is completely false. Progesterone does a lot more that protect the uterus from the effects of Estrogen. There are several tissues that have Progesterone receptors and therefore needs Progesterone to counter Estrogen for optimal function. These tissues include the kidneys, thyroid, bone and central nervous system.
In the kidneys, progesterone acts as a natural diuretic. It causes the body to get rid of sodium by blocking the activity of a chemical called aldosterone, and water follows the sodium out and is excreted in the urine. Estrogen causes water retention and swelling, so progesterone nicely balances this effect of estrogen.
Progesterone causes an increase in thyroid levels which will cause your body to carry out more efficient metabolism. By contrast, estrogen increases the amount of thyroxine-binding globulin, a protein which binds to thyroid hormone, decreasing the amount of active thyroid for your body to use. This results in decreased metabolism and increased fat storage, so again we see the purpose in balancing estrogen and progesterone in hormone replacement therapy.
In bone, progesterone stimulates osteoblast activity. Osteoblasts are the cells responsible for bone formation. Estrogen inhibits osteoclast activity. Osteoblast are the cells responsible for bone formation. Osteoclasts are the cells responsible for absorbing bone back into the body. Here, we see progesterone complementing estrogen to prevent bone loss associated with menopause and assisting in bone formation.
In the nervous system, progesterone reduces anxiety by exerting effects on GABA receptors in the brain. When GABA receptors are activated, a sedative effect is produced in the body. The action of progesterone on GABA receptors is helpful in treating sleeplessness, anxiety and can help regulate blood pressure. Estrogen is responsible for forming excitatory pathways in the brain again showing the opposite nature of estrogen’s effects on the body compared to progesterone.
Progesterone is a hormone which exhibits it affects on multiple tissues in the female body and not just on uterus tissue. Progesterone is the yin of estrogens yang. It should be replaced along with estrogen with or without a uterus.