Diagnosis Code for Ordering DEXA in Prostate Cancer Patients on LHRH Agonist Therapy
Use the diagnosis code for "drug-induced osteoporosis" or "secondary osteoporosis" when ordering DEXA bone density scans for patients with prostate cancer receiving LHRH agonist therapy, as androgen deprivation therapy (ADT) should be classified as a cause of secondary osteoporosis. 1
Primary Diagnostic Approach
Recommended Diagnosis Codes
- Drug-induced osteoporosis is the most appropriate diagnosis, as LHRH agonist therapy directly causes accelerated bone loss through testosterone suppression 1
- When using the FRAX fracture risk calculator, ADT should be entered under "secondary osteoporosis" 1
- Alternative acceptable codes include "osteoporosis associated with androgen deprivation therapy" or "treatment-related bone loss" 1
Clinical Justification for DEXA Ordering
Baseline DEXA scanning is indicated before initiating LHRH agonist therapy in men at increased fracture risk based on FRAX screening. 1 The evidence strongly supports this approach:
- 41% of men with newly diagnosed prostate cancer already have osteoporosis at baseline, and 39% have osteopenia 2
- LHRH agonist therapy causes significant bone loss: 1.2% at 1 year, 3.7% at 2 years, and up to 12.7% at 6 years 2
- The incidence of bone fractures in patients on LHRH agonists is approximately 6%, with fractures occurring at a mean of 28 months after treatment initiation 3
Timing and Follow-Up Recommendations
Initial Screening
- Obtain baseline DEXA scan before starting LHRH agonist therapy in all men at increased fracture risk 1
- DEXA scans should be performed in patients at risk for cancer treatment-induced accelerated bone loss 1
Follow-Up Monitoring
- Repeat DEXA scan after 1 year of therapy as recommended by the International Society for Clinical Densitometry 1
- For patients with osteoporosis or on treatment, repeat DEXA in 1-2 years to monitor treatment effectiveness 4
- Annual DEXA monitoring may be warranted given the rapid bone loss that occurs within the first 6 months of LHRH agonist therapy 5
Supporting Documentation for Insurance Authorization
Key Clinical Facts to Include
- LHRH agonist therapy causes hypogonadism, a recognized cause of osteoporosis in men 6
- Bone turnover markers are significantly elevated in patients on LHRH agonists (N-telopeptide 80.1 vs 30.1 in controls, P<0.001) 6
- Patients with osteopenia have a 60% risk of progressing to osteoporosis after 2 years of LHRH agonist therapy 2
Risk Factors to Document
- Age >70 years (higher baseline osteoporosis risk) 1
- Low body weight (<70 kg) 1
- Family history of fractures 1
- Prior fragility fracture 4
- Smoking or excess alcohol intake 1
- Inadequate calcium intake or vitamin D deficiency 1
Common Pitfalls to Avoid
- Do not use "screening for osteoporosis" as the primary diagnosis, as this may not adequately convey the treatment-induced nature of the bone loss and could result in insurance denial 1
- Do not wait for symptoms or fractures to occur before ordering DEXA, as bone loss begins immediately with LHRH agonist initiation and is most rapid in the first 6 months 5
- Do not assume normal baseline bone density means no monitoring is needed, as significant bone loss occurs even in men with initially normal BMD (12.7% loss at 6 years) 2
- Ensure the diagnosis code clearly links the DEXA scan to the LHRH agonist therapy, as this establishes medical necessity for insurance coverage 1
Additional Clinical Context
The guidelines emphasize that all men receiving ADT should be counseled about osteoporosis risk prior to treatment and managed according to National Osteoporosis Foundation guidelines 1. This includes:
- Supplemental calcium (1200 mg/day) and vitamin D3 (800-1000 IU/day) for all men >50 years 1
- Additional pharmacologic treatment when 10-year hip fracture probability is ≥3% or major osteoporotic fracture probability is ≥20% 1
- Treatment options include denosumab (60 mg subcutaneously every 6 months), zoledronic acid (5 mg intravenously annually), or alendronate (70 mg orally weekly) 1