What are the guidelines for Dual-Energy X-ray Absorptiometry (DEXA) scans in middle-aged women with Primary Biliary Cholangitis (PBC) and a potential history of autoimmune diseases or chronic conditions?

DEXA Screening Guidelines for Primary Biliary Cholangitis

All patients with PBC should undergo baseline DEXA scanning at diagnosis to assess bone mineral density, with follow-up screening intervals of 1-2 years for those with normal BMD, or annually for high-risk patients including those with cirrhosis, advanced cholestasis, postmenopausal women, or those on corticosteroids. 1

Who Should Be Screened

Universal Screening Recommendations

• All patients with PBC require risk assessment for osteoporosis at presentation 1
• DEXA scanning should be performed at baseline for all PBC patients, as osteoporosis affects 20-44% of this population, with the majority having osteopenia 1
• The high prevalence of bone disease in PBC (approximately 30% have osteoporosis) justifies universal screening rather than selective approaches 1

Priority Groups Requiring Immediate DEXA

• All patients with cirrhosis 1
• Postmenopausal women 1
• Patients with previous fragility fractures 1
• Those receiving corticosteroid therapy (prednisolone ≥5 mg/day for >3 months) 1
• Patients with low body mass index (<19 kg/m²) 1
• Older age patients 1
• Male patients with cholestatic liver disease (who have higher disease-related osteoporosis risk increase than females, though lower absolute risk) 1
• Patients being evaluated for liver transplantation 1

DEXA Scanning Protocol

Initial Assessment

• Measure bone mineral density at lumbar spine and hip using dual-energy X-ray absorptiometry 1
• Obtain lateral X-rays of dorsal and lumbar spine to identify vertebral fractures 1
• Note that lumbar spine measurements may be unreliable in elderly patients due to osteophytes and spinal deformity 1

Interpretation Thresholds

• Osteoporosis: T-score ≤ -2.5 1
• Osteopenia: T-score between -1.0 and -2.5 1
• High fracture risk: T-score < -1.5 in PBC patients, which supports initiating specific therapy 1
• Vertebral fractures are associated with T-scores lower than -1.5 in cholestatic liver disease 1

Follow-Up Screening Intervals

Standard Risk Patients

• Repeat DEXA every 2-3 years if initial BMD is normal, similar to the non-cirrhotic population 1
• Follow-up assessment should occur between 1-5 years depending on initial results and general osteoporosis risk 1

High-Risk Patients Requiring Annual DEXA

• Cholestatic patients with more than one risk factor for osteoporosis 1
• Patients on high-dose corticosteroid therapy recently initiated 1
• Patients with advanced cirrhosis, particularly those eligible for transplantation 1
• Those with severe cholestasis (bilirubin >3× upper limit of normal for >6 months) 1

Adjunctive Risk Assessment Tools

FRAX Score Utilization

• Use the WHO FRAX score (with or without BMD values) to estimate 10-year predicted absolute fracture risk 1
• Alternative: QFracture tool (cannot incorporate BMD values) 1
• Following initial risk assessment, measure BMD with DEXA in patients whose fracture risk is near intervention threshold, then recalculate absolute risk using FRAX with the BMD value 1

Laboratory Evaluation

• Assess calcium and vitamin D metabolism 1
• Biochemical markers of bone turnover can be measured but are primarily helpful for monitoring treatment response rather than diagnosis 1
• Note that bone markers may be affected by hepatic fibrosis extent in chronic liver disease 1

Important Clinical Considerations

Common Pitfalls to Avoid

• Do not delay DEXA screening until symptoms develop, as fracture prevalence ranges 7-35% in PBC patients 1
• Recognize that inaccuracies in BMD measurements can occur in patients with cirrhosis or chronic cholestasis 1
• Be aware that falls occur with increased frequency in PBC due to associated autonomic dysfunction, compounding fracture risk 1
• Patients with a clinical history of falls should be referred to a specialist falls clinic for multidisciplinary assessment 1

Special Populations

• Pre-transplant patients: DEXA is mandatory before liver transplantation, as 30% have osteoporosis and 25-35% develop fractures within the first post-transplant year 1
• Male patients: Though less commonly affected by PBC, males with cholestatic disease have proportionally higher disease-related osteoporosis risk increases 1

Treatment Implications Based on DEXA Results

• T-score < -2.5 or pathological fracture: Bisphosphonates (typically alendronate) are indicated 1
• T-score < -1.5: Bisphosphonate therapy may be appropriate given high hip and vertebral fracture risk 1
• All patients should receive calcium (1000-1500 mg/day) and vitamin D (400-800 IU/day) supplementation regardless of DEXA results 1
• Lifestyle modifications including weight-bearing exercise, smoking cessation, and minimizing alcohol intake should be advised universally 1