Natural Progesterone-What Role in Women's Healthcare?
Whether it's right for your patient depends on the specific setting
by Jane L. Murray, M.D. (September 1998)
Biochemistry, Physiological Activity,
Injection, Vaginal, Rectal, Sublingual, Intrauterine
Uses: Menopausal HRT,
Disorders, Menstrual-related Allergies,
||Summary, Primary Points
Natural progesterone (which has a chemical structure identical to that
of the hormone produced in humans) is essentially nontoxic, has few side
effects, and is less expensive than synthetic progestins. It may be more
effective than its synthetic counterparts in certain situations, such
as postmenopausal HRT. Its use in other settings, such as osteoporosis
prevention and treatment, shows promise. Data are unclear concerning its
role in the premenstrual syndrome, affective disorders, menstrual-related
allergy symptoms, and benign breast disease. Natural progesterones
various routes of administration allow clinicians to determine the most
effective dose and delivery for each patient. (Women's Health
In Primary Care 1998: 1(8):671-687)
Today's popular women's health literature is replete with suggestions
for using natural hormones to prevent and treat a variety of health problems.1-6
Natural progesterone is often promoted as an alternative to synthetic
progestins for two reasons:
- It appears to have fewer side effects in many women.7
- It may have more benefit for lipid profile enhancement,8
osteoporosis prevention,9 and the treatment of menopausal
symptoms,10 premenstrual syndrome (PMS), 11,12
A cultural move toward that which is "natural" and away from
man-made chemicals is a current theme voiced by consumers of health care.
Many women express the desire to take charge of their own health by eschewing
mainstream medical treatment and prescription drugs, and by seeking help
from so-called alternative health care providers who recommend nutrition,
nutritional supplements, and lifestyle adjustments, as well as natural
hormones in the form of creams and phytoestrogens in whole foods. In fact,
it has been established that nearly one third of Americans seek care from
alternative health care practitioners14much of this care
for women's health concerns.
Primary care clinicians are confronted daily with questions from patients
regarding alternative approaches to many women's health problems. This
article will provide an overview of mainstream medical research about
natural progesterone and its potential uses to help women with a variety
of health issues. With such information, primary care clinicians may be
better equipped to answer patients' questions, and may more knowledgeably
utilize natural progesterone in those circumstances where it may be appropriate
or even preferable to synthetic progestational agents and other drugs.
First, a word of clarification. The term natural in the context
of hormone discussions does not necessarily mean that the hormone in question
is derived from a source in nature. The term refers to an agent that has
a chemical structure identical to that of the hormone molecule produced
in the human body. Conjugated estrogens, for example, contain hormones
derived from a natural sourcehorse urine. However, conjugated equine
estrogens have a chemical structure different from that of any of the
estrogens produced in humans.
Conversely, micronized progesterone is manufactured in a laboratory from
chemicals derived from plants (Mexican wild yams and soy), yet it has
a molecular structure identical to that of the progesterone produced in
humans. Throughout this paper, the term progesterone refers to
the chemical substance made in humans, which is shown in (Figure 1).
Synthetic analogues of progesterone are often labeled progestogens,
progestins, or progestational agents.Unfortunately, the
medical literature and common usage often interchange these synthetic
terms with the word progesteronewith much confusion.
Synthetic analogues of progesterone have been developed to make the hormone
available orally and to produce longer lasting and more potent effects
than would be available from progesterone itself. Most of these compounds
were first developed for use as contraceptive agents. Many of them bind
to receptors for glucocorticoids, androgens, and mineralocorticoids, as
well as those for progesteronel5 explaining the diverse side
effects many women experience while taking progestins: acne, menstrual
irregularities, migraines, striae, and weight gain. Emotional side effects
can include depression, mood swings, and irritability.
Progestins commonly in use in American medicine include:
Medroxyprogesterone acetate (MPA), which is used
to manage dysfunctional uterine bleeding, as a contraceptive (in
injectable form), and as an adjunct to postmenopausal hormone replacement
Norethindrone (or norethisterone) and norethindrone
acetate, which are common constituents of oral contraceptives.
Megestrol acetate, which is used for cancer treatment.
17-a-hydroxyprogesterone caproate, which is used
as a long-acting injectable progestin.
Norgestrel, which is often combined with synthetic
estrogens in oral contraceptives.15
The chemical structures of several common progestins are
shown in (Figure 2).
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