Introduction
Osteoporosis is a skeletal condition characterized by reduced density and increased fragility of bones, with an increased tendency to fractures. It's more prevalent with age. According to the surgeon general's report on Bone Health and Osteoporosis (2004), one of every two women older than 50 has an osteoporosis-related fracture at some point, with an increasing risk with age.
Personal differences are recognized in the predisposition to osteoporosis. The national osteoporosis foundation lists such risk factors for the development of osteoporosis as sex, age, family history, previous fractures, social habits including alcohol and tobacco use, lack of exercise, certain disease conditions such as inflammatory bowel disease and certain cancers and certain medications, particularly steroids.
The sex steroids produced by the gonads, the mineralocorticoids and the glucocorticoids--produced by the adrenal cortex--are the three main classes of steroids produced in the body. The surgeon general's report specifically notes the use of steroids in the class of the glucocorticoids as the most common cause of drug-induced osteoporosis.
Glucocorticoids in Osteoporosis
Glucocorticoids are drugs that mimic the effects of cortisol, a steroid hormone released from the adrenal cortex. The effects of this hormone are felt by almost every organ system in the body. Its effects on the skeletal system include the direct suppression of bone formation by suppressing the maturation and increasing the death of bone-forming cells called osteoblasts. Cortisol also reduces the absorption of calcium in the intestines and calcium loss in urine, which lowers the blood levels of calcium and triggers the release of calcium from bone. This further weakens the bones. Production of the bone health-friendly sex steroids--estrogen in women and testosterone in men--is also suppressed by this hormone. The results of the suppression of sex steroid release are deficiencies in bone formation and increase in bone breakdown or resorption.
Medications that mimic cortisol (such as prednisone) are widely used in medicine, particularly in chronic conditions where they're used as anti-inflammatory agents. They are used in conditions such as systemic lupus erythematosus, asthma, chronic bronchitis and emphysema, inflammatory bowel diseases including ulcerative colitis Crohn's disease and rheumatoid arthritis, and other chronic arthritis. Their long-term use and effects on bone health was the subject of the 70th meeting of the FDA's endocrinologic and metabolic drugs advisory committee in 1998.
Recommendations
The surgeon general's report recommends the use of the lowest possible doses of steroids and the shortest possible duration of treatment with these drugs. Local treatment in the form of inhalers, sprays, drops and creams are also strongly recommended where feasible to reduce systemic effects that would harm bone health and predispose someone to the development of osteoporosis.
