Dual-Energy X-ray Absorptiometry (DEXA) is a specialized diagnostic imaging tool used to measure bone mineral density (BMD), primarily in the hip and spine. DEXA scan results are used to diagnose osteoporosis, assess fracture risk, and monitor treatment effectiveness. Medicare coverage for this procedure requires “medical necessity.” This necessity is communicated using standardized administrative tools, specifically the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) and Current Procedural Terminology (CPT) coding systems. Understanding these precise criteria ensures the test is covered and patients avoid unexpected costs.
Medicare Eligibility Requirements for Bone Density Scans
Medicare does not cover DEXA scans for the general population; coverage is limited to patients who meet specific clinical risk factors outlined in the National Coverage Determination (NCD 150.3). These five defined indications establish the medical need for the procedure before any codes are applied. The first qualifying group includes women who are estrogen-deficient and are determined by their physician to be at clinical risk for developing osteoporosis. This category often applies to postmenopausal women who are not on hormone replacement therapy.
A second criterion covers individuals who have vertebral abnormalities, such as those detected on a standard X-ray, that may be indicative of underlying osteoporosis or a previous vertebral fracture. Another significant risk factor involves individuals who are receiving or are expected to receive long-term glucocorticoid therapy. This must be a dose equivalent to 5.0 milligrams or more of prednisone per day, planned to last for a period exceeding three months.
The presence of primary hyperparathyroidism, a condition characterized by high levels of parathyroid hormone, also qualifies an individual for a covered bone mass measurement. Finally, Medicare provides coverage for individuals who are actively being monitored by their healthcare provider. This monitoring is done to assess the response to or the efficacy of any drug therapy approved by the U.S. Food and Drug Administration (FDA) for the treatment of osteoporosis.
Establishing Medical Necessity Through Diagnostic Codes
The specific ICD-10-CM code chosen by the ordering provider translates the patient’s qualifying medical condition directly into the language required for Medicare billing. The code must precisely reflect one of the five medical necessity criteria established by the National Coverage Determination. For example, a code like Z13.820 is used to document a routine screening for osteoporosis in an asymptomatic individual who meets one of the risk criteria, such as an estrogen-deficient woman.
If a patient is on systemic steroid medication, the ICD-10 code Z79.52 denotes the long-term current use of systemic steroids, linking the patient’s medication history to the coverage requirement. For patients already diagnosed with the disease, codes within the M80-M82 range are used to specify the type of osteoporosis, such as M81.0 for age-related primary osteoporosis. The specific diagnostic code justifies the procedure and determines whether the claim will be accepted.
When the DEXA scan monitors osteoporosis treatment effectiveness, specific codes are necessary. For example, Z79.83 (long-term use of bisphosphonates) communicates that the patient is on an FDA-approved drug regimen, fulfilling the monitoring requirement. The physician’s documentation must always support the selected ICD-10 code, ensuring a clear link between the medical record and the billed service.
Frequency Limitations and Procedural Documentation
Medicare generally limits coverage for a bone mass measurement to once every two years. This standard frequency applies to most covered beneficiaries, including those undergoing initial screening or routine monitoring. Exceptions to this rule exist for patients undergoing more aggressive management or therapy changes.
For individuals being monitored to assess the response to an FDA-approved osteoporosis drug, a follow-up scan may be covered as frequently as once every 12 months. Similarly, a repeat scan may be necessary and covered sooner than two years after a significant change, such as starting long-term glucocorticoid therapy. The procedural codes used for the DEXA scan itself are CPT 77080 for the axial skeleton (spine and hip) and CPT 77081 for the appendicular skeleton (peripheral sites).
In addition to the national rules (NCDs), local Medicare Administrative Contractors (MACs) may issue Local Coverage Determinations (LCDs) that can influence billing specifics or accepted ICD-10 codes within a particular geographic region. If a provider orders a scan that falls outside the covered frequency or lacks a justifying ICD-10 code, the patient must be informed beforehand by signing an Advanced Beneficiary Notice (ABN). The ABN acknowledges the patient may be responsible for the cost if Medicare denies the claim due to a lack of medical necessity.