Estrogen and progesterone are both female hormones produced in the ovaries. The primary function of both hormones is to produce primary female characteristics, such as the breasts, and regulate the menstrual cycle. Estrogen and progesterone also play an important role in maintaining a healthy pregnancy and carrying the fetus to term. In addition to all of their functions as sex hormones, estrogen and progesterone contribute significantly to bone health and preventing bone loss.
Estrogen and Bones
When the body is depleted of the calcium it needs to carry out basic functions such as muscle contraction, it leaches calcium from the bones. The bones must then absorb more calcium to maintain bone integrity. Failure to adequately absorb calcium is one cause of bone loss from osteoporosis and osteopenia. The body uses a hormone called calcitonin to help the bones absorb calcium. A study published in 1990 in "The Journal of Endocrinological Investigation" indicates that estrogen supplementation in menopausal women increases the levels of calcitonin in the blood. The increase in calcitonin prevented more bone loss in these women than in the group that did not take estrogen.
Progesterone and Bones
Calcitonin puts calcium into the bones but it's specialized cells, called osteoblasts, that use the mineral to build new bone tissue. If you do not have enough osteoblasts, or if the osteoblasts are not active enough, you will not produce enough bone tissue -- another cause for osteopenia and osteoporosis. A study published in 2004 in "Endocrine Abstracts" indicates that progesterone is responsible for the rapid growth of osteoblasts within the bone tissue.
Menopause and Hormone Replacement Therapy
During menopause, the production of female hormones slowly decreases. The process last several years, and during that time, the body may produce estrogen and progesterone erratically until it stops altogether. As a result, hormone levels fluctuate, which not only affects the reproductive system, it also affects bone health. Uneven estrogen causes fluctuations in calcitonin levels, which prevents the bones from absorbing calcium efficiently. Fluctuations in progesterone levels prevent the osteoblasts from building bone efficiently. Hormone replacement therapy equalizes hormone levels to maintain constant calcium absorption and bone growth.
Hormone Replacement Considerations
While hormone replacement does prevent bone loss, it also presents risks. Estrogen and progesterone supplementation cause an increased risk of blood clots, heart disease and stroke. Women may also experience menstrual side effects, such as spotting, bloating and cramping, and breast tenderness. Consult your physician if you are considering estrogen and progesterone replacement for bone loss.
References
- NetDoctor; Female Hormones; Gillian Rice; 2011
- Journal of Endocrinological Investigation; Calcitonin and Estrogens; D. Agnusdei et al.; 1990
- Endocrine Abstracts; Inactivating Progesterone Metabolism in Human Osteoblasts; K. Kaur et al.; 2004
- National Institute on Aging: Hormones and Menopause
- PubMed Health; Menopause; 2010
- "Principles of Anatomy and Physiology"; Gerard J. Tortora et al; 2010
