Distribution of 24-Hour Urinary Calcium Excretion and Bone Metabolism Relationships
Overview
This multicenter cross-sectional study of 1239 Chinese adults established reference intervals for 24-hour urinary calcium excretion (UCaE) and revealed sex- and age-related differences in UCaE distribution. The study found that 24-hour UCaE/Ucr positively correlates with vitamin D levels in both sexes and with parathyroid hormone and bone turnover markers in men only.
Background
Calcium is essential for bone strength and various physiological functions, with urinary calcium excretion reflecting calcium metabolism balance. Elevated UCaE may indicate excessive intake or increased bone resorption, while low UCaE suggests deficiency or impaired absorption. Bone turnover markers (BTMs) provide dynamic assessment of bone remodeling and fracture risk, complementing bone mineral density measurements. Large-scale data on 24-hour UCaE distribution and its relationship with bone metabolism in the Chinese population have been lacking.
Data Highlights
Parameter
Overall Median (mmol)
Men Median (mmol)
Women Median (mmol)
Hypercalciuria Prevalence (%)
24-hour UCaE
2.27
2.24
2.28
11.6 (Men 7.5; Women 14.0)
24-hour UCaE/Ucr (Men, age 30-44)
0.70 (median)
24-hour UCaE/Ucr (Men, age 18-29)
0.46 (median)
24-hour UCaE/Ucr (Women)
Gradual increase with age
Key Findings
The median 24-hour UCaE was 2.27 mmol overall, with similar values in men (2.24 mmol) and women (2.28 mmol).
Men aged 30-44 years had the highest 24-hour UCaE/Ucr ratio (median 0.70), while men aged 18-29 had the lowest (median 0.46); women showed a gradual increase in UCaE/Ucr with age.
24-hour UCaE/Ucr was independently positively associated with serum 25(OH)D levels in both men (P = .032) and women (P < .001).
In men, 24-hour UCaE/Ucr was independently associated with parathyroid hormone (PTH) (P = .031), β-CTX (P = .021), and P1NP (P = .048), but these associations were not observed in women.
The prevalence of hypercalciuria was 11.6% overall, higher in women (14.0%) than men (7.5%), and varied significantly by age group and geographic region (P < .05).
Clinical Implications
These findings provide reference intervals for 24-hour UCaE in the Chinese adult population, aiding in the identification of calcium metabolism abnormalities. The sex-specific associations between UCaE and bone metabolism markers suggest that clinicians should consider gender differences when interpreting urinary calcium results. Monitoring 24-hour UCaE alongside bone turnover markers and vitamin D status may improve assessment and management of bone metabolic disorders.
Conclusion
This study establishes normative data for 24-hour urinary calcium excretion in Chinese adults and highlights gender differences in its relationship with bone metabolism. These insights enhance understanding of calcium homeostasis and support tailored clinical evaluation of bone health.
References
CHANCES Study Group 2024 -- Distribution of 24-Hour Urinary Calcium Excretion and Its Relationship with Bone Metabolism
