1. Addition of a progestin when a woman has not had a
hysterectomy
Studies of the addition of a progestin for 10 or more days of a
cycle of estrogen administration, or daily with estrogen in a continuous
regimen, have reported a lowered incidence of endometrial hyperplasia than would
be induced by estrogen treatment alone. Endometrial hyperplasia may be a
precursor to endometrial cancer.
There are, however, possible risks that may be associated with the use of
progestins with estrogens compared to estrogen-alone regimens. These include a
possible increased risk of breast cancer, adverse effects on lipoprotein
metabolism (e.g., lowering HDL, raising LDL) and impairment of glucose
tolerance.
2. Elevated blood pressure
In a small number of case reports, substantial increases in blood
pressure have been attributed to idiosyncratic reactions to estrogens. In a
large, randomized, placebo-controlled clinical trial, a generalized effect of
estrogens on blood pressure was not seen. Blood pressure should be monitored at
regular intervals with estrogen use.
3. Hypertriglyceridemia
In patients with pre-existing hypertriglyceridemia, estrogen
therapy may be associated with elevations of plasma triglycerides leading to
pancreatitis and other complications.
4. Impaired liver function and past history of cholestatic
jaundice
Estrogens may be poorly metabolized in patients with impaired
liver function. For patients with a history of cholestatic jaundice associated
with past estrogen use or with pregnancy, caution should be exercised and in the
case of recurrence, medication should be discontinued.
5. Hypothyroidism
Estrogen administration leads to increased thyroid-binding
globulin (TBG) levels. Patients with normal thyroid function can compensate for
the increased TBG by making more thyroid hormone, thus maintaining free T4 and T3 serum concentrations in the
normal range. Patients dependent on thyroid hormone replacement therapy who are
also receiving estrogens may require increased doses of their thyroid
replacement therapy. These patients should have their thyroid function monitored
in order to maintain their free thyroid hormone levels in an acceptable
range.
6. Fluid retention
Because estrogens may cause some degree of fluid retention,
patients with conditions that might be influenced by this factor, such as a
cardiac or renal dysfunction, warrant careful observation when estrogens are
prescribed.
7. Hypocalcemia
Estrogens should be used with caution in individuals with severe
hypocalcemia.
8. Ovarian cancer
The CE/MPA substudy of WHI reported that estrogen plus progestin
increased the risk of ovarian cancer. After an average follow-up of 5.6 years,
the relative risk for ovarian cancer for CE/MPA versus placebo was 1.58 (95%
confidence interval 0.77 – 3.24) but was not statistically significant. The
absolute risk for CE/MPA versus placebo was 4.2 versus 2.7 cases per 10,000
women-years. In some epidemiologic studies, the use of estrogen alone, in
particular for ten or more years, has been associated with an increased risk of
ovarian cancer. Other epidemiologic studies have not found these
associations.
9. Exacerbation of endometriosis
Endometriosis may be exacerbated with administration of
estrogens. A few cases of malignant transformation of residual endometrial
implants have been reported in women treated post-hysterectomy with estrogen
alone therapy. For patients known to have residual endometriosis
post-hysterectomy, the addition of progestin should be considered.
10. Exacerbation of other conditions
Estrogens may cause an exacerbation of asthma, diabetes mellitus,
epilepsy, migraine or porphyria, systemic lupus erythematosus, and hepatic
hemangiomas and should be used with caution in women with these conditions.