Endocrine Abstracts

Elderly residents are at high risk for vitamin D deficiency due to immobilization or little opportunity of uv exposure. Decreased cutaneous capacity to form cholecalciferol and diets low in calcium and vitamin D add to this problem.

In a prospective cohort study that we performed in 95 institutions in four different provinces of Austria we found that 93% of all patients had a 25(OH)D level ≤20 ng/ml. Aim of this study was to analyse whether differences exist in terms of parathyroid hormone and calcium metabolism as well as bone ultrasound measurements at different sites among groups of patients who already have very low levels of vitamin D (<15 ng/ml). Blood samples were collected in the months of May and June in a cohort of 961 female residents above 70 (mean age 84±6 years). Eighty percent of the patients had serum creatinine levels ≤1.2 and the remainder levels ≤1.8 mg/dl. We formed following 25(OH)D groups: 0–4.9 (group A), 5–9.9 (group B), and 10–15 ng/ml (group C). Residents of group A were on average 3 years older and had a slightly less BMI. Multivariate analysis adjusted for age, BMI, mobility status and creatinine clearance demonstrated that group A had significantly lower corrected serum calcium levels (difference 0.07 mmol/l), a 28% increase in serum osteocalcin, a 95% increase in serum PTH levels compared to group C (all P<0.005). Quadriceps muscle strength was 12% lower in group A (P<0.01) as was the stiffness index at the calcaneus: Z-score −0.48 (vs −0.04 in group C, P<0.005). Radial and phalangeal SOS measurements were similarly low in all groups.

Our study demonstrates that even within a group of patients with already low 25(OH)D levels patients show significant differences in subgroups of vitamin D deficiency in parameters relating to muscle strength, degree of hyperparathyroidism, bone turnover and bone mass.