A medical contraindication is a factor or condition that increases the risks to your health (and life) from taking a particular drug, undergoing a specific medical procedure, or undertaking a particular activity. Some contraindications are absolute, which means there are no reasonable circumstances for taking the drug or course of action. For example, a person with an anaphylactic food allergy should never eat that particular food in any amount whatsoever.

Other contraindications are relative, meaning that the patient is at higher risk of complications, but that these risks may be outweighed by other considerations or mitigated by other medical measures. Caution and second opinions are advisable in these cases.

Absolute Contraindications

• severe liver disease
• pregnancy
• coronary artery disease (CAD)
• venous thrombosis
• well-differentiated and early endometrial cancer

Relative Contraindications

• migraine headaches
• personal history of breast cancer
• history of uterine fibroids
• atypical ductal hyperplasia of the breast
• active gallbladder disease

The National Institutes of Health (NIH) has released a cautionary statement on short-term side effects of Prempro that is a good follow-up to this article.

WARNING

Estrogens and progestins should not be used for the prevention of cardiovascular disease. The Women’s Health Initiative (WHI) reported increased risks of myocardial infarction, stroke, invasive breast cancer, pulmonary emboli, and deep vein thrombosis in postmenopausal women during 5 years of treatment with conjugated equine estrogens (0.625 mg) combined with medroxyprogesterone acetate (2.5 mg) relative to placebo. Other doses of conjugated estrogens and medroxyprogesterone acetate, and other combinations of estrogens and progestins were not studied in the WHI …

Estrogens are part of a class of chemicals in the body called steroid hormones. There are several closely related ones in a woman’s body all made from estrodiol, the main form. They are just one of several classes of steroid hormones in women’s bodies important to health. The others include:

• Progesterone — steroid hormone needed for pregnancy
• Testosterone — sex steroid in men with a small amount in women
• Cortisol — a steroid involved in immune functions, also known as the “stress hormone”
• Vitamin D — modified hormone important to bones
• Aldosterone — a steroid that acts in the kidneys to regulate sodium balance.

Steroid hormones share two important characteristics: they are made in the body in extremely small amounts and they act only in specific tissues of the body, each important to women’s health. For example, we know that estrogen is important to breast health. Too much estrogen can stimulate growth of breast cells. Certain types of estrogen can attack healthy breast cells and even cause DNA changes, becoming a catalyst for the growth of malignant breast tumors.

By looking at the pathway by which estrogen works in the body, it is easier to understand how too much estrogen can be damaging. This outline is drawn from the work of cancer researcher, Jon J. Michnovicz, MD, PhD, director, Foundation for Preventive Oncology

1. Estrogen is produced in the body.
2. Estrogen circulates throughout the body.
3. Estrogen binds to estrogen receptors in the breast.
4. Estrogen is broken down and eliminated.

Most estrogen is produced in the ovaries, beginning when a woman is 12 to 14 years of age and continuing until menopause, when a woman is about 50 to 55 years of age. But even after menopause, estrogen continues to be produced in the body but the main sources are now fat and muscle tissue, instead of the ovaries.

Estrogen circulates in the bloodstream from the ovaries or fat cells to the breasts and other organs, attached to a “carrier molecule” in the blood called, sex hormone-binding globulin or SHBG. The carrier molecule attaches to estrogen in the bloodstream, once it has been produced, and transports it to the cells that are able to use it.

Estrogen is captured from the bloodstream by a specialized cell protein which is able to recognize estrogen. These estrogen receptors are found mainly in the breasts and uterus, with smaller amounts in the skin, bone, brain, and liver.

The Key and Lock

Once an active estrogen molecule binds to an estrogen receptor in a cell, that cell’s DNA becomes activated. As a result, the cell can now grow. Estrogen acts like a key put into a lock. Once the key is inserted, DNA is activated.

Estrogen is broken down and eliminated in a process called cell metabolism. Once the estrogen has done its work, it is chemically metabolized (changed) in order to help the body eliminate the by-products in the urine and through the intestines. Some intestinal estrogen residues can be returned to the bloodstream and recycled, once urinary estrogen is eliminated.

Reducing Risks

There appear to be two types of estrogen metabolites, known as C-16 and C-2. The C-2 form is inactive but the C-16 remains active in a woman’s body, and is able to attack DNA and cause abnormal growth of breast cells. Substances in common fruits and vegetables, scientists have found, are capable of reducing the formation of the dangerous C-16 estrogen metabolites in women’s bodies, and encouraging the production of the safer, inactive C-2 forms of estrogen. These influences can modify each of the four steps in the estrogen cycle shown above. These and other elements of a healthful diet and lifestyle combine to reduce the risks estrogen poses for abnormal growth in breast tissue.

Ordinarily, a woman’s body tries to maintain a balance of estrogen activity that is neither too high or too low. Hormonal checks and balances usually operate smoothly and unobserved. The delicate balance only becomes evident when levels are either insufficient or excessive.

When You Have Too Much

While some tissues, such as bones, benefit from having lots of estrogen, other tissues, namely the breasts and uterus, do not. Estrogen causes breast cells to multiply, leading to dense breasts. In general, women in western industrial countries, like Britain and the U.S., have much denser breasts than Japanese women. The greater density of Western women’s breast tissue is related to higher levels of estrogen, scientists have confirmed.

In almost all of the known and suspected risks for breast cancer, abnormal and/or excessive estrogen activity is implicated as a factor. Scientists now agree that estrogen encourages the growth of malignant breast cells when they arise. Strong evidence of estrogen’s link to breast cancer was found in follow-up studies to the Women’s Health Study, the clinical trial that was ended prematurely.

Excessive Levels, Excessive Risks

Multiple blood samples were collected and frozen from the 16,000 participants in the trial and saved for later tracking for breast cancer over time. In a group of older, post-menopausal women who were tracked, higher estrogen levels in the blood were strongly associated with developing malignant breast cancer in later years. As a result of this and other studies, breast cancer researchers have concluded that, if breast cancer rates are to be reduced, It is necessary to reduce the excessive levels of estrogen throughout the population, particularly in women at higher risk.

Risk Factors Include…

• Reproductive factors, such as early menarche and late first birth, late menopause, and no breast-feeding;
• Individual and genetic factors, such as positive family history of breast cancer, benign breast disease, tall height, and older age;
• Environmental factors, such as use of oral contraceptives, estrogen replacement hormones (such as Prempro), alcohol, radiation, and pesticide exposure;
• Lifestyle factors, such as high animal protein diet, lack of exercise, obesity.

Many medical and research scientists now are committed to reducing the dangers of estrogen to women’s breast tissue. Newer guidelines and practices by physicians reflect this dramatic shift in prescribing practices.