Bone Abstracts

Background: Despite the large amount of studies published on the association of vitamin D deficiency with higher incidence of falls and fractures, the threshold for a sufficient serum 25(OH)D concentration remains subject to a considerable debate. There has also been no clear consensus on the assessment and treatment of vitamin D deficiency.

Objective: To examine the prevalence of vitamin D deficiency and/or insufficiency and its impact on calcium/phosphate homeostasis as well as on bone turnover in a major German cohort of individuals with defined clinical risk factors (CRF) for osteoporosis and fractures (acc. to German DVO Guideline 2009, and QFracture Score 2013).

Results: In 2014 we examined a total of 7,253 patients (mean age =62.6 yrs (S.D. 13.9); f 64.4%, m 35.6%) with CRF for osteoporosis and fractures. The prevalence of 25(OH)D serum levels <75 nmol/l was 87.7%. 25(OH)D serum levels below 50 nmol/l (deficiency) and 25 nmol/l (severe deficiency) have been detected in 55.0 and 15.7% of patients, respectively. Elevated PTH levels (>65 ng/l) have been found in 20.9% of 5,119 samples tested - with an inverse correlation to 25(OH)D serum levels (P<0.05) and positive relationship to increased bone turnover markers (B-AP, OC, DPD). The prevalence of secondary hyperparathyroidism (sHPT) was highest in patients with severe Vitamin D deficiency (35.3%) but common also in patients with 25(OH)D serum levels between 50 and 75 nmol/l (13.5%).

Conclusion: The high prevalence of vitamin D deficiency or insufficiency in a major cohort of patients with CRF for osteoporosis demonstrates the importance of routine measurements of 25(OH)D diagnostic and therapeutic purposes. The results put into question the approach adopted in various national guidelines which do not recommend 25(OH)D routine measurements. Additional consideration of PTH serum levels may contribute to a more adequate estimate of individual vitamin D supplementation needs.