@willowmena You have posed a very good (and hard) question. According to Gemini:

Evaluating treatment response typically involves a combination of imaging alternatives and biochemical markers:
1. Alternative Imaging Options
Hip-Only DEXA Scans: While a full DEXA evaluates both the spine and hips, a damaged spine often skews results due to artifacts like hardware, severe degenerative changes, or compression fractures. However, a hip-only DEXA remains fully valid and interpretable. Because anabolic medications like Tymlos increase bone mineral density systemically (though to varying degrees), tracking changes at the total hip and femoral neck can provide a reliable proxy for overall skeletal response.
Quantitative Computed Tomography (QCT): QCT can assess volumetric bone mineral density (vBMD) specifically at the spine or hip. Unlike a 2D DEXA projection, QCT software can isolate specific vertebrae or avoid damaged areas, though it involves a higher radiation dose.

2. Biochemical Bone Turnover Markers (BTMs)
Because Tymlos is an anabolic (bone-building) therapy, it stimulates bone formation significantly faster than it stimulates bone resorption early in the treatment course. Blood or urine markers can show whether the medication is actively engaging bone metabolism within weeks to months—long before a density scan can register a change.

Formation Markers: Tests like P1NP (Serum procollagen type I N-propeptide) typically rise sharply within 1 to 3 months of starting an anabolic drug, confirming that the bone-building cells (osteoblasts) are responding to the treatment.
Resorption Markers: Tests like CTX (Serum C-telopeptide) measure bone breakdown. While formation should outpace resorption on Tymlos, tracking both gives a complete picture of bone turnover dynamics.

3. Clinical and Functional Tracking
Height and Posture Monitoring: Severe spinal damage often stems from silent micro-fractures or structural collapse. Tracking height accurately over time and noting any stabilization in posture can help clinically indicate that vertebral integrity is being maintained.
Incident Fracture Assessment: The ultimate clinical goal of Tymlos is fracture reduction. Vigilant tracking of new pain episodes or structural changes via diagnostic X-rays (when clinically warranted) helps ensure the spine is protected.

Are you seeing an endocrinologist? or bone specialist? They should be able to give you guidance also.