Update on Osteoporosis

When serial BMD assessment is appropriate

• When it is used to determine whether treatment should be initiated (in untreated patients) because of significant bone loss
• To monitor response to therapy by identifying an increase or stabilization of BMD
• To identify nonresponse by documenting a loss of BMD, suggesting the need for treatment re-evaluation and assessment for a secondary cause of osteoporosis
• To follow-up earlier assessment when the expected change in BMD equals or exceeds the least significant change
• When the interval is appropriate for the patient’s clinical status. (In general, BMD assessment is performed 1 year after initiation or change of therapy, with longer intervals once a therapeutic effect has been established.)
• When the patient is using a medication associated with rapid bone loss, such as glucocorticoid therapy. In such a patient, more frequent testing may be appropriate.
• Note that these recommendations differ slightly from ACOG’s statements regarding the use of DXA.

Diagnosis of osteoporosis

• According to the WHO international reference standard, osteoporosis can be diagnosed when a patient has a T-score of –2.5 or below at the femoral neck. The reference standard from which the T-score is calculated is the white female population aged 20 to 29 years in the National Health and Nutrition Examination Survey (NHANES) III database.
• Osteoporosis also may be diagnosed in postmenopausal women and men aged 50 or older when the T-score of the lumbar spine, total hip, or femoral neck is –2.5 or below. In some circumstances, the
  33% radius (also called the 1/3 radius) may be utilized.
• Other hip regions of interest, including Ward’s area and the greater trochanter, should not be used for diagnosis.

A move away from use of the term “osteopenia”

• The term may be retained, but “low bone mass” or “low bone density” is preferred
• People with low bone mass or low bone density do not necessarily have a high risk of fracture.

WHAT THIS EVIDENCE MEANS FOR PRACTICE
DXA testing remains the cornerstone of diagnosis for patients at risk for fragility fracture. It also is the optimal method to determine the need for pharmacotherapy. In some instances, however, overutilization of DXA imaging has led to overtreatment, especially in younger women with low bone mass, when treatment is based on variables other than diminished bone quality (including, “small-boned” women, genetics, and failure to achieve peak bone mass as high as one’s peer group prior to menopause).
These recommendations help to clarify the rationale for follow-up DXA imaging for patients on therapy, an area in which scientific unanimity is lacking.

Related Article: What is the optimal interval for osteoporosis screening in postmenopausal women before fracture occurrence and osteoporosis treatment initiation? Steven R. Goldstein, MD (Examining the Evidence, August 2012)

IN ADOLESCENTS AND YOUNG WOMEN, CONSIDER THE BONE EFFECTS OF ORAL CONTRACEPTIVES

Ziglar S, Hunter TS. The effect of hormonal oral contraception on acquisition of peak bone mineral density of adolescents and young women. J Pharm Pract. 2012;25(3):331–340.

The bone loss observed in adolescents and young women who use depot medroxyprogesterone acetate (Depo-Provera) for contraception led to an FDA-mandated boxed warning on the medication’s package insert. The effect of oral contraceptives (OCs) on bone growth has received little publicity, however.

The best strategy to offset the natural loss of bone associated with aging and the menopausal transition is to ensure the development of maximal bone mass in youth. When maximal BMD is not achieved, the risk of osteoporosis is increased.

Adolescence is a critical period of bone mineralization, which is mediated by endo­genous estradiol. The highest rate of bone mass accrual occurs 1 year before and 3 years after menarche. Young women who consume a diet low in calcium or who have an eating disorder, who fail to exercise, who smoke, or who have low estrogen status are most likely to have low peak bone mass.

OCs suppress endogenous estradiol production by interrupting the hypothalamic-pituitary-ovarian axis. By replacing endogenous estradiol with ethinyl estradiol (EE), OCs establish and maintain new hormone levels. Early initiation and use of very-low-dose EE increases the likelihood that the accrual of bone mass will be jeopardized at a critical time of bone mineralization.

Details of this meta-analysis
Ziglar and Hunter reviewed 11 prospective trials that showed a decrease in bone mass in adolescents and young women who used low-dose OCs, six trials that showed a neutral effect, and one trial that found an increase in bone mass. This last study involved only members of the US military whose level of daily exercise may not be representative of the general population of women the same age. Investigators also theorized that the use of norethindrone acetate as an androgenic progestin in this study may have exerted a positive effect on bone accrual.