Understanding Uterine Fibroids

Uterine fibroids are non-cancerous muscle tumors of the womb, they usually occur from a single clone of a uterine cell (called a myocyste), but can eventually produce a variety of shapes and locations that symptoms can vary significantly.

The most common symptoms from a fibroid are due to heavy or prolonged menstrual bleeding. Other symptoms include pelvic pressure, discomfort with sex, and urinary frequency.

In addition to symptoms due to size they are actually production plants for estrogen. If a woman has a number of uterine fibroids, and they have different characteristics they each has developed into a fibroid from a separate cell that evolved. The evolution of a fibroid actually stems from a gene defect. 

Since 80% of women will have a uterine fibroid prior to menopause, many are not symptomatic in most people. And about 50% of women with a fibroid will have symptoms from them.

Uterine fibroids do begin to develop in early reproductive life. Treatments depend on the size, the location, the goals of the patient, the amount of menstrual bleeding.

Uterine fibroids are hormone sensitive, and they literally are powerhouses of estrogen. . All uterine muscle cells have receptors for estrogen and progesterone. Thus a uterine cell s stimulated to grow by these hormones. A uterine fibroid tumor has a greater density of these receptors than in the case of most uterine cells.  In pregnancy this is a very effective strategy, hormones trigger growth as a pregnancy progresses. But in the case of uterine fibroid, the excessive growth is the source of many of the complications of fibroids.

The hormone sensitivity of uterine fibroids also produces a estrogen excessive environment. This is a situation where the uterine fibroids adhere (also known as binding) to the estrogen molecules. Thus there is more estrogen and this can be responsible for many of the associated symptoms.  Not only that but the fibroid cells are able to manufacture estrogen from other molecules. This also responsible for the powerhouse of estrogen. Obese women, or women with other high estrogen conditions like PCOS are more likely to have uterine fibroids.

Oddly women who smoke have lower risk of fibroids do to the fact that their estrogen levels are lower. Other risk factors include your genetics, how much time has passed since a pregnancy, food additives and soybean milk. Being thin, using oral contraceptives, using DMPA, are associated with decrease risk of uterine fibroids.

If your fibroid has grown or changed, it is important to get accurate ultrasound measurements measurements, to determine if this is true. It is equally important to know if you have other reasons for excess estrogen so that you can try to mitigate the side effects. Generally the largest fibroid present in a uterus grows about 35% per year!

It has never been shown that birth control pills or even other estrogen hormone treatments cause fibroids to grow. It is not clear why this would be so. It could be the types of hormones, the dosage, or the fact that local and genetic factors are so dominant that supplemental hormones don’t have an effect. Since a uterine fibroid is a powerhouse of estrogen it is probably possible to alter that fact and help to shrink the fibroid. That is where all the new research is going.  

Antiprogesterone and other new hormonal therapies do however help to shrink fibroids. If you are interested in participating in a clinical research study of uterine fibroids call Women’s Health Practice, 217-356-3736.


Suzanne Trupin, MD, Board Certified Obstetrician and Gynecologist and owner of Women's Health Practice, Hada Cosmetic Medicine, and Hatha Yoga and Fitness

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