Bone loss, contraception and lactation

Abstract

Loss of bone mass with age, is a universal phenomenon and is more pronounced in women than in men. The condition where the bone loss has proceeded to the extent that fractures occur is termed osteoporosis. As the number of elderly persons in the population increases, its magnitude is likely to increase, both in the developing and the developed countries. Bone mass increases rapidly in childhood and the adolescent years, reaching a peak in the third decade of life, and begins to decline soon thereafter. Several factors are thought to influence bone loss: these include race, diet, smoking, and physical exercise. Although the rate of bone loss accelerates in the immediate postmenopausal period, the process actually begins in the premenopausal years. By the time osteoporosis is clinically apparent and manifested by fracture, it probably cannot be reversed. The peak adult bone mass achieved, and the subsequent rate of bone loss are the major factors that determine a woman's susceptibility to postmenopausal osteoporosis. A primary cause of bone loss after menopause is the associated decline in ovarian function. Scanty information is available on the factors that affect bone mineral density or initiate bone loss before menopause, although both estrogens and progestins have been shown to prevent bone loss in postmenopausal women. Available data on the relationship between steroid hormone contraceptive use and bone mass/density is limited to combined oral contraceptives and one report related to the use of depot medroxyprogesterone acetate.(ABSTRACT TRUNCATED AT 250 WORDS)

PIP: Woman lose bone mass with age at a faster rate than do men. Osteoporosis is the condition when bone loss is so great that fractures occur. It is difficult to reverse bone loss once it has occurred. Bone mass peaks in the 20s and starts to deteriorate shortly thereafter. The rate of bone loss is fastest in the period immediately after menopause. Peak bone mass and subsequent rate of bone loss are the chief determinants of a woman's susceptibility to osteoporosis. The decline in ovarian function is largely responsible for postmenopausal bone loss. Possible factors of bone loss are race, diet, smoking, and physical exercise. Evidence suggests that estrogens and progestins protect against bone loss in women after menopause and is almost entirely limited to combined oral contraceptives (OCs). Other studies do not show OCs to benefit bone mass. 1 study shows an association between depot medroxy progesterone acetate and bone mass/density. The different findings are as result of the difficulties in controlling many variables in studies with small numbers of subjects with low statistical power and in making conclusions from studies done when OC dosages and formulations were changing and diagnostic techniques were advancing. Besides, osteoporosis has a complex nature. We still do not know whether hormonal contraception continues to protect against bone loss throughout the postmenopausal years when bone loss accelerates. Further, it is clear whether the beneficial effect of hormonal contraception is specific to the trabecular bone, which is more likely to respond to metabolic influences than is cortical bone. Studies show that lactation benefits and adversely affects bone mass. The research does suggest, however, that calcium intake during lactation, duration of lactation, and age at lactation are linked to bone mass. We must consider also the anatomic site and the technique used to measure bone mass. A study is needed to consider all these factors simultaneously,