Gender-Dependent Characteristics of Serum 1,25-Dihydroxyvitamin D/25-Hydroxyvitamin D Ratio for the Assessment of Bone Metabolism

Abstract

Objectives Vitamin D deficiency, which is common worldwide, increases the risks of falls and fractures and can lead to increased morbidity and mortality. However, the clinical utility and relevance of vitamin D activation remain unknown. The aim of the present study was to clarify the clinical usefulness of serum 1,25-dihydroxyvitamin D (1,25D)/25-hydroxyvitamin D (25D) ratio for assessment of the extent of bone metabolism. Methods We retrospectively screened data for 87 patients whose serum 1,25D and 25D levels were measured. Eight patients who were taking vitamin D preparations were excluded, and data for 79 patients (33 males and 46 females) were analyzed. Since menopausal status can be associated with serum vitamin D level, we divided the patients by gender and divided the female patients into two groups at the age of 50 years. Results The median serum 1,25D/25D ratio was significantly lower in males than in females, with the most considerable difference in all males [4.1 (interquartile range: 2.3-5.8) × 10 −3 ] versus elderly females (aged ≧50 years) [7.9 (3.3-10.1) × 10 −3 ). Main disorders were endocrine (30.6%), inflammatory (18.5%), and bone-related (16.7%) disorders. The ratios of serum 1,25D/25D had significant negative correlations with femoral dual-energy X-ray absorptiometry % young adult mean (DEXA %YAM) ( R= −0.35) and lumbar DEXA %YAM ( R= −0.32). Significant correlations were found between the 1,25D/25D ratio and serum levels of inorganic phosphate (iP), parathyroid hormone, and alkaline phosphatase (ALP). The 1,25D/25D ratio had gender-specific characteristics: the ratio was significantly correlated with age in males ( R= −0.49), while it was significantly correlated with BMI in females ( R= 0.34). Conclusions The results of this study suggested that vitamin D activity is negatively correlated with bone mineral density, being reduced in aged males but enhanced in obese females.

Relationship between patients’ characteristics and efficacy of calcimimetics for primary hyperparathyroidism in the elderly

“…Since alendronate increases BMD in PHPT patients, it may be useful for patients with bone loss who do not undergo parathyroidectomy 24 . Our previous study suggested that upregulated vitamin D activity, estimated by the serum 1,25(OH) 2 D/25(OH)D ratio, might be associated with disruption of bone metabolism, 25 and the increased serum 1,25(OH) 2 D/25(OH)D ratio in the present study may be related to bone loss in PHPT patients. Urinary cAMP excretion and nephrogenous cAMP level are known to be elevated in patients with PHPT, reflecting the effect of oversecreted PTH 26 .…”