Drug-Induced and Glucocorticoid-Associated Bone Disease

Some medications weaken the skeleton as an adverse effect, raising the risk of fragility fracture. By far the most important is glucocorticoid (steroid) therapy, the leading cause of drug-induced osteoporosis. Because glucocorticoids are widely used in rheumatology and other fields, the bone harm they cause is a recurring concern at the intersection of treatment and skeletal health.

Definition

Drug-induced bone disease is the impairment of bone strength caused by medications as an adverse effect; glucocorticoid-induced osteoporosis, the most common form, is skeletal fragility resulting from the effect of glucocorticoids on bone cells.

Scope

This entry covers how drugs — chiefly glucocorticoids — impair bone, the mechanisms involved, the timing and magnitude of the resulting fracture risk, and the existence of guidance addressing it. Other medications associated with bone loss are noted in general terms. The entry is reference-educational and non-prescriptive; it does not advise on starting, stopping, or dosing any medication.

Core questions

• Which medications can harm bone?
• How do glucocorticoids damage the skeleton at the cellular level?
• How quickly does fracture risk rise after starting glucocorticoids?
• Why can fractures occur before bone density falls markedly?
• What guidance exists for glucocorticoid-induced osteoporosis?

Key concepts

• Glucocorticoid-induced osteoporosis
• Osteoblast and osteocyte apoptosis
• Suppressed bone formation
• Early increase in fracture risk
• Dose- and duration-dependence
• Secondary osteoporosis
• Other bone-affecting drugs

Mechanisms

Glucocorticoids harm bone mainly by suppressing bone formation: they inhibit the generation of osteoblasts and promote the apoptosis of osteoblasts and osteocytes, reducing the team of bone-forming and bone-maintaining cells (Weinstein et al., 1998). They also transiently increase bone resorption early in treatment and impair calcium handling. The net effect is rapid bone loss and a deterioration in bone quality that begins soon after therapy starts (Weinstein, 2011). Other medication classes are associated with bone loss through different routes — for example, agents that suppress sex hormones or alter mineral handling — but glucocorticoids are the prototype and the best characterized.

Clinical relevance

Drug-induced bone disease is clinically important because the offending agents are common and the resulting fractures are largely a consequence of treatment rather than the underlying illness alone. Recognizing the pattern explains why skeletal health is monitored during glucocorticoid therapy. This entry provides that background for reference only and does not give individualized advice about medication use or fracture prevention.

Epidemiology

Oral glucocorticoid use is associated with a rapid, dose-dependent rise in fracture risk that increases soon after starting therapy and recedes after stopping, with vertebral fractures particularly affected (Van Staa et al., 2000). A notable feature is that fractures can occur at higher bone-density values than in postmenopausal osteoporosis, reflecting glucocorticoids' impact on bone quality as well as quantity (Weinstein, 2011).

Evidence & guidelines

The mechanistic basis rests on laboratory studies of glucocorticoid effects on bone cells (Weinstein et al., 1998), the epidemiology on large cohort analyses (Van Staa et al., 2000), and management on dedicated guidance such as the American College of Rheumatology guideline for glucocorticoid-induced osteoporosis (Buckley et al., 2017). The present entry summarizes these sources without reproducing specific clinical recommendations.

History

Bone loss was recognized as a hazard of corticosteroid therapy soon after these drugs entered clinical use in the mid-twentieth century. Cellular studies in the 1990s identified suppression of bone formation and induction of osteoblast and osteocyte apoptosis as central mechanisms, and large pharmacoepidemiologic studies and dedicated guidelines later quantified the risk and framed its management.

Key figures

• Robert S. Weinstein
• Stavros Manolagas
• Tjeerd-Pieter van Staa
• Cyrus Cooper

Seminal works

• weinstein-1998
• van-staa-2000
• weinstein-2011

Frequently asked questions

Why are glucocorticoids especially harmful to bone?

They suppress bone formation by reducing the generation of osteoblasts and promoting the death of osteoblasts and osteocytes, while also transiently increasing resorption, so bone is lost rapidly and its quality declines.

How soon does fracture risk increase after starting steroids?

Risk rises early — within months of beginning oral glucocorticoids — in a dose-dependent way, and tends to decline after the drug is stopped, according to large cohort data.

Can fractures happen even if bone density is not very low?

Yes; glucocorticoids impair bone quality as well as density, so fragility fractures can occur at density values that would not be classified as osteoporotic in postmenopausal osteoporosis.