Diagnosis Code for DXA Scan in Prostate Cancer Patients on LHRH Agonist Therapy
Use ICD-10 code Z79.818 (Long-term [current] use of other agents affecting estrogen receptors and estrogen levels) as the primary diagnosis code to order a DXA scan for a patient with prostate cancer receiving LHRH agonist injections for hormone management.
Rationale for Code Selection
The appropriate diagnosis code reflects the indication for bone density screening, which is the long-term use of androgen deprivation therapy (ADT), not the underlying prostate cancer itself. LHRH agonists cause medical castration and significantly increase the risk of bone loss and osteoporosis, making bone density monitoring medically necessary 1.
Supporting Diagnosis Codes
You should also include the following codes to provide complete clinical context:
- C61 (Malignant neoplasm of prostate) - This documents the underlying condition being treated 1
- Z79.818 - This is the key code that justifies the DXA scan based on the medication-induced bone loss risk 1
Clinical Context for Bone Density Monitoring
Men receiving LHRH agonist therapy for prostate cancer require bone density monitoring because ADT causes significant bone loss. The guidelines consistently recommend neoadjuvant LHRH agonist therapy for 4-6 months for men receiving radical radiotherapy for high-risk disease, with adjuvant hormonal therapy for 2-3 years recommended for men at high risk of prostate cancer mortality 1. This prolonged exposure to androgen suppression substantially increases fracture risk.
Duration and Risk Factors
- Patients receiving long-term ADT (>6 months) have the highest risk of bone loss 1
- The risk is particularly elevated in patients receiving 2-3 years of adjuvant hormonal therapy combined with radiotherapy 1
- Men starting LHRH agonist therapy should be informed about bone health and the importance of monitoring 1
Common Pitfalls to Avoid
Do not use only the prostate cancer diagnosis code (C61) without the medication code (Z79.818). Insurance payers typically require documentation that the DXA scan is medically necessary based on a specific risk factor - in this case, the long-term use of hormone therapy that affects bone metabolism. The medication code provides this justification.
Do not delay ordering the baseline DXA scan. Ideally, bone density should be assessed before initiating LHRH agonist therapy or shortly after starting treatment to establish a baseline for monitoring subsequent bone loss during the course of androgen deprivation therapy 1.