Calcium2026-05

Context-Dependent Association Between Serum 25-Hydroxyvitamin D and Romosozumab Bone Mineral Density Response: A Stratified Analysis by Renal Function Category and Prior Treatment History in a Real-World Japanese Cohort.

Nakano Ryo, Ichisawa Ayumi, Saruta Kenya, Kogawa Masakazu et al. — Nutrients

Summary

This study explored how vitamin D levels might affect the effectiveness of romosozumab, an osteoporosis drug, in Japanese patients. It found that the impact of vitamin D on bone density improvements could vary depending on a person's kidney function and whether they had previously used other bone treatments. This suggests a personalized approach to vitamin D might be beneficial for some patients.

AI-generated summary — read the original

Key points

Vitamin D levels may influence how effectively the osteoporosis drug romosozumab improves bone density.
This influence appears to differ based on a patient's kidney function.
A patient's history of previous osteoporosis treatments also seems to play a role.
These findings suggest that a personalized approach to vitamin D might be important for some patients.

What the study looked at

This study aimed to understand if a person's vitamin D level affects how well the osteoporosis drug romosozumab works to improve bone density. Researchers also investigated if factors like kidney function or a history of previous bone treatments change this relationship. This was a retrospective study, meaning researchers looked back at existing medical records. They analyzed data from 315 Japanese patients who received romosozumab for 12 months. Patients were grouped based on their kidney health (normal vs. moderately reduced function) and whether they had previously taken other osteoporosis medications. The team then examined the connection between initial vitamin D levels and changes in bone density after a year of treatment. The study revealed that the association between vitamin D levels and romosozumab's effect on bone density was not straightforward. For patients with normal kidney function, higher vitamin D was linked to lower markers of bone breakdown. However, this link was absent in those with moderately reduced kidney function. Interestingly, among patients who had previously used other osteoporosis drugs, lower vitamin D levels were associated with a greater improvement in bone density from romosozumab, a pattern not seen in patients new to treatment.

Dietary takeaway

While calcium is essential for strong bones, this study suggests that for individuals taking specific osteoporosis medications like romosozumab, the ideal vitamin D level might need to be considered individually, especially if they have kidney issues or a history of other bone treatments. This highlights the importance of discussing your calcium and vitamin D intake with your doctor, particularly when managing osteoporosis. Remember, this is one study, and more research is needed to confirm these findings before they can be broadly applied to clinical practice.

Abstract

Serum 25-hydroxyvitamin D (25OHD) is a key determinant of calcium-phosphorus homeostasis and bone metabolism; however, its role as a modifier of the bone mineral density (BMD) response to romosozumab, a dual-action anabolic agent for osteoporosis, remains poorly characterized, particularly across different levels of renal function. This study investigated whether the renal function category and prior treatment history modified the association between baseline 25OHD and romosozumab BMD response. We conducted a retrospective cohort study of 315 consecutive Japanese patients treated with romosozumab (210 mg subcutaneously monthly for 12 months) at Mutsu General Hospital, Aomori, Japan (2019-2025; IRB approval RO7-5; date of approval: 20 January 2026). Patients were stratified by eGFR-based renal function category: preserved renal function (eGFR ≥ 60 mL/min/1.73 m, n = 199) and moderately reduced renal function (eGFR 30-59 mL/min/1.73 m, n = 86). Patients with severely reduced renal function (eGFR 15-29, n = 11) were excluded from the comparative analyses. Spearman rank correlations (Rs) were computed between baseline 25OHD and (i) baseline TRACP-5b and (ii) 12-month lumbar spine BMD changes. Mediation analysis was performed to examine TRACP-5b as a potential mediator. In the preserved renal function group, baseline 25OHD was significantly and inversely correlated with TRACP-5b (Rs = -0.246, = 0.0007). This correlation was absent in the moderately reduced renal function group (Rs = +0.036, = 0.74), and the interaction was statistically significant (z = -2.38, = 0.017). Among treatment-experienced patients, lower 25OHD levels were correlated with greater LS-BMD response (Rs = -0.197, = 0.036), whereas no such correlation was observed in treatment-naïve patients (Rs = -0.009, = 0.902). Mediation analysis did not identify TRACP-5b as a significant mediator. The association between serum 25OHD and romosozumab BMD response appears to be context-dependent across renal function categories and prior treatment history. These findings are hypothesis-generating and require prospective validation before they can be applied to clinical practice.

View on PubMed →DOI: 10.3390/nu18101642