Laboratory Monitoring for Romosozumab Therapy
For patients on romosozumab therapy, regular monitoring should include serum calcium, phosphate, creatinine, alkaline phosphatase (ALP), and urinary calcium:creatinine ratio. 1
Initial Laboratory Assessment
Before starting romosozumab therapy, the following baseline tests should be performed:
- Serum calcium, phosphate, and creatinine 1
- Alkaline phosphatase (ALP) - total serum ALP for children and bone-specific ALP for adults 1
- 25(OH) vitamin D levels 1
- Parathyroid hormone (PTH) 1
- Spot urine calcium and creatinine to calculate urinary calcium:creatinine ratio 1
- Estimated glomerular filtration rate (eGFR) 1
Monitoring During Treatment
Calcium and Phosphate Monitoring
- Monitor fasting serum phosphate levels every 2 weeks during the first month of treatment 1
- Continue monitoring every 4 weeks for the following 2 months 1
- After 3 months of stable dosage, monitor as clinically appropriate 1
- Measure fasting serum phosphate level 4 weeks after any dose adjustment 1
Additional Laboratory Monitoring
- Monitor serum calcium levels regularly to detect hypocalcemia 1
- Measure urinary calcium:creatinine ratio to assess for hypercalciuria 1
- Monitor 1,25(OH)₂ vitamin D levels every 6 months as a safety parameter 1
- Monitor serum creatinine to assess renal function 1
Imaging Studies
- Kidney ultrasonography at least every 2 years in patients without nephrocalcinosis 1
- Annual kidney ultrasonography in patients with nephrocalcinosis and/or persistent hypercalciuria 1
- Consider cranial MRI if signs of intracranial hypertension develop 1
Special Considerations
Bone Turnover Markers
- Tartrate-resistant acid phosphatase 5b (TRACP-5b) and intact type I procollagen N-terminal propeptide (iP1NP) may be useful to monitor treatment response 2, 3
- Changes in these markers after 1 month of treatment correlate with BMD changes after 4-6 months 2
Cardiovascular Risk
- Due to potential cardiovascular risks, patients with history of myocardial infarction or stroke in the preceding year should not receive romosozumab 4, 5
- Monitor for signs and symptoms of cardiovascular events during treatment 6, 5
Clinical Follow-up
- Regular follow-up visits every 6 months are recommended for patients on romosozumab therapy 1
- Assess for adverse effects including injection site reactions, which occur in 4-5% of patients 5
- Monitor for bone and joint pain, disability, and fatigue 1
Important Caveats
- Regular measurement of serum FGF23 levels is not recommended as it does not guide therapy 1
- Dual-energy X-ray absorptiometry (DXA) or peripheral quantitative computed tomography (pQCT) are not routinely recommended for monitoring during treatment 1
- After completing romosozumab treatment, sequential therapy with an anti-resorptive agent is recommended to maintain bone mineral density gains 4