Can Crohn's disease cause bone loss?

Crohn's Disease and Bone Loss

Yes, Crohn's disease significantly increases the risk of bone loss, with approximately 35-40% of patients suffering from osteopenia and 15% from osteoporosis. 1

Mechanisms of Bone Loss in Crohn's Disease

• Uncontrolled inflammation contributes directly to bone loss through inflammatory cytokines 1, 2
• Malabsorption of calcium, vitamin D, and possibly vitamin K leads to decreased bone mineralization 2
• Increased bone resorption occurs in Crohn's disease patients as evidenced by elevated urinary deoxypyridinoline levels 3
• Hypogonadism induced by inflammatory bowel disease can contribute to bone loss 2
• Low body mass index (BMI) correlates with lower bone mineral density 1

Differences Between Crohn's Disease and Ulcerative Colitis

• Bone loss is more common in Crohn's disease (32-38% have osteopenia) compared to ulcerative colitis (23-25% have osteopenia) 2
• Studies show reduced bone mineral density (BMD) in Crohn's disease patients but less consistently in ulcerative colitis 1
• The mean deficit in spine BMD is greater in Crohn's disease (0.44±0.08 Z-scores) than in ulcerative colitis (0.34±0.08) 2

Risk Factors for Bone Loss in Crohn's Disease

• Corticosteroid use is a major risk factor, with BMD correlating negatively with lifetime steroid use 1
• Low dietary intake of calcium and zinc is associated with reduced femoral neck BMD 4
• Active disease phase shows significantly reduced BMD compared to remission 4
• Malnutrition and weight loss contribute to bone loss 1
• Lack of physical activity further compromises bone health 1

Clinical Implications

• Increased fracture risk is observed, particularly for spine fractures (RR=2.2,95% CI: 1.2-4.0) 2
• Patients with Crohn's disease may present with bone pain and increased fracture risk 5
• Secondary hyperparathyroidism may develop as a consequence of calcium malabsorption 5

Monitoring and Assessment

• Patients with high FRAX score (≥20% major fracture and ≥3% hip fracture) should have bone mineral density assessed 1
• Those aged under 40 with risk factors or receiving prolonged (>3 months) or repeated courses of corticosteroids should undergo bone densitometry 1
• Monitoring vitamin D levels is important as deficiency occurs in more than half of patients with Crohn's disease 1

Management Recommendations

• All patients receiving corticosteroids should receive 800-1000 mg/day calcium and 800 IU/day vitamin D supplementation 1
• Lifestyle modifications including regular physical exercise and smoking cessation are essential 1
• Patients starting corticosteroids should be assessed for osteoporosis risk; those at high risk should start bisphosphonate therapy 1
• Anti-resorptive agents such as bisphosphonates may be particularly effective due to the increased bone resorption seen in Crohn's disease 3
• Treating the underlying inflammation is important for bone health 1

Pitfalls and Caveats

• FRAX score does not discriminate between past versus current corticosteroid use, nor does it stratify risk according to doses beyond 7.5 mg 1
• Osteomalacia may co-exist with osteoporosis, especially before treatment, and will require specific vitamin D treatment 1
• Budesonide, despite having lower systemic activity, may still be associated with lumbar spine and femoral neck bone loss and does not confer an advantage over low-dose prednisone for bone preservation 6
• Calcium supplementation without vitamin D may increase cardiovascular risk 1