Diagnosis Code for Ordering DEXA Scan in Prostate Cancer Patients on LHRH Agonist Therapy
Use the diagnosis code for "drug-induced osteoporosis" or "secondary osteoporosis" when ordering DEXA scans for patients receiving LHRH agonist therapy for prostate cancer, as androgen deprivation therapy (ADT) should be explicitly considered a cause of secondary osteoporosis. 1
Primary Diagnostic Approach
The appropriate ICD-10 code is M81.4 (Drug-induced osteoporosis) or M81.8 (Other osteoporosis), as LHRH agonist therapy directly causes hypogonadism leading to accelerated bone loss 2, 3
NCCN guidelines explicitly state that "ADT should be considered 'secondary osteoporosis' when using the FRAX algorithm", establishing this as the correct diagnostic framework 1
Alternative acceptable codes include Z79.83 (Long-term use of hormone replacement therapy) combined with Z87.310 (Personal history of osteoporosis fracture) if applicable, though the secondary osteoporosis designation is most accurate 1
Clinical Justification for Insurance Authorization
NCCN guidelines recommend obtaining a baseline DEXA scan before starting ADT in men at increased risk for fracture based on FRAX screening, providing clear clinical indication 1
The rationale should explicitly state that LHRH agonists cause sustained testosterone suppression leading to accelerated bone loss, with studies showing 1.2-6.5% BMD decrease in the first 1-3 years 4
Document that 41% of men with newly diagnosed prostate cancer already have osteoporosis at baseline, and 60% of osteopenic patients develop osteoporosis within 2 years of LHRH agonist therapy 4
Timing and Frequency of DEXA Scanning
Order the baseline DEXA scan before initiating LHRH agonist therapy to establish fracture risk and guide preventive treatment decisions 1
Follow-up DEXA scans should be performed after 1 year of therapy as recommended by the International Society for Clinical Densitometry 1
Subsequent monitoring intervals are every 2 years for standard risk patients, though annual scanning may be justified in high-risk individuals 5
Anatomic Sites to Include in Order
Order DXA of the lumbar spine and hip(s) as the primary modality (ACR appropriateness rating: 9/9) 1, 5
Include femoral neck measurement in addition to total hip and lumbar spine (L2-L4) for comprehensive fracture risk assessment 5, 6
Consider adding distal forearm DXA in patients with advanced degenerative spine changes or scoliosis that may artificially elevate spine BMD readings 1, 5
Common Pitfalls to Avoid
Do not use generic "screening for osteoporosis" as the indication, as this may be denied for male patients under age 70 without documented risk factors 1
Avoid ordering DEXA more frequently than annually, as the precision of measurements and rate of bone turnover make more frequent scanning clinically unhelpful 5
Do not rely solely on spine DXA in elderly patients with degenerative disease, as spuriously elevated BMD from spondylosis occurs in >81% of falsely elevated measurements 5
Never use peripheral DXA or quantitative ultrasound for diagnosis in this population, as these are screening tools only and cannot be interpreted using WHO criteria 5
Supporting Documentation for Authorization
Include the specific LHRH agonist medication name and duration of therapy (e.g., "Patient on leuprolide for 6 months") 2, 3
Reference that bone loss begins immediately with ADT, with significant decreases in BMD occurring within the first year (1.2-1.8%) and accelerating over time 4
Note that fracture risk is increased even without metastatic bone disease, as studies show fractures occur at non-metastatic sites in 6% of patients on long-term LHRH agonist therapy 3
Document any additional risk factors such as age >70, prior fracture, family history of hip fracture, low body weight (<70 kg), smoking, or glucocorticoid use 1