EVALUATION FOR SECONDARY OSTEOPOROSIS

Evaluation of patients requires attention to possible secondary causes for low bone mass. Individuals with low bone mass may have diseases or take medications that may increase the risk of osteoporosis. Laboratory investigations in patients with low bone mass reveal that up to 50% may have underlying disorders such as vitamin D deficiency or hypercalciuria. Laboratory tests to identify common causes of secondary osteoporosis include a complete blood cell count and differential, erythrocyte sedimentation rate, routine chemistry profile, 25-hydroxyvitamin D level, thyroid stimulating hormone, parathyroid hormone, and 24-hour urine for measurement of calcium excretion. Correction of the underlying cause may impact BMD and fracture risk.

NONPHARMACOLOGIC THERAPY

Patient and Physician Education. Education strategies coupled with appropriate follow-up and reinforcement can increase compliance. Education on fall risk, exercise programs, dietary advice including adequate calcium and vitamin D intake, and other life style modifications are an important first step. Propensity to fall should be undertaken, with modification of such risk factors through effective intervention when possible.

Exercise. Exercise induces skeletal mechanotransduction that increases bone strength by creating small gains in bone mass. Exercise in children appears to be most effective prior to attainment of peak bone mass especially combined with calcium intake. Moderate, regular weight-bearing exercise is essential for skeletal health, both for effects on bone strength and fall prevention.

Smoking, Alcohol, and Caffeine. Smoking is toxic to bone cells, and smokers have lower hip BMD and increased fracture risk. In postmenopausal women, bone density has been shown to be inversely correlated to pack-years of smoking and rates of bone loss were greater in smokers. Serum vitamin D levels were lower in smokers, and estradiol levels were lower in patients on estrogen replacement therapy. The Nurses’ Health Study found that fracture risk fell after 10 years of abstinence from smoking. Excess alcohol, three or more drinks per day, is associated with lower bone mass and increased fall propensity. Excessive caffeine may decrease intestinal calcium absorption, lower dietary calcium intake, and induce hypercalciuria.

Calcium and Vitamin D. Prepubertal twins randomized to calcium supplements have been shown to have greater gains in BMD over a 3-year period than placebo patients. Calcium alone is not sufficient to prevent early postmenopausal bone loss but may slow the rate of loss. In the U.S. NHANES III survey, higher calcium intake was associated with higher BMD in women. In men and women, BMD was shown to be higher with increasing 25(OH)D levels and vitamin D was the dominant predictor of BMD relative to calcium intake.

Vitamin D promotes calcium absorption from the gut, retention in the body, and incorporation into bone. Dietary sources of vitamin D are limited to certain fish products. Most of our vitamin D comes from dermal synthesis after ultraviolet light exposure. Doses of 800 to 1000 IU/day and in some instances larger doses may be needed. Severe vitamin D deficiency may cause osteomalacia and is associated with secondary hyperparathyroidism, decreased intestinal calcium absorption, and calcium loss from the skeleton to maintain serum calcium. Gains in BMD may be seen in individuals with correction of severe deficiency within several months. Patients supplemented with vitamin D have improved muscle function and fall risk.

Individuals with osteoporosis randomized to calcium and vitamin D significantly reduced the risk of vertebral, nonvertebral, and hip fractures. Oral vitamin D has been shown to reduce nonvertebral fractures by at least 20%.

Fall Prevention. Almost one third of persons aged 70 years and older will sustain a fall each year, with higher numbers reported in women, older individuals, and nursing home residents. Falls are a major source of morbidity and increased mortality, and about 5% result in a fracture. Studies show fall risk is related to a history of falls, medications, or conditions that may predispose to falls including cognitive, visual or auditory impairments, decreased muscle strength, increased body sway, and poor balance. Such conditions are more prevalent in older individuals, and falls increase as the number of risk factors rises.