Is there an epidemic vitamin D deficiency in German orthopaedic patients?

Abstract

Background: Vitamin D plays an essential role in bone health and muscle function. Some studies have shown a widespread rate of vitamin D deficiency in the general population, but few have reported on the vitamin D status of orthopaedic patients.

Questions/purposes: We investigated (1) the extent of hypovitaminosis D in orthopaedic patients, (2) seasonal variations in vitamin D levels, and (3) possible risk factors for insufficient vitamin D levels.

Methods: Vitamin D levels in 1119 patients consecutively admitted to an orthopaedic surgery department in 2011 were measured. To investigate the correlation between climate factors and vitamin D levels, the sunshine hours for each month in 2011 were collected by Deutscher Wetterdienst (the German weather service) in the region where most tested patients lived. The prevalence of normal (> 30 ng/mL), insufficient (20-30 ng/mL), and deficient (< 20 ng/mL) 25-hydroxyvitamin D levels was determined. Univariate and multivariate analyses were used to assess risk factors for insufficient vitamin D levels.

Results: Overall, 84% of patients had insufficient levels of vitamin D and 60% were vitamin D deficient. Only 15% were in the target range of 30 to 60 ng/mL. The prevalence of low vitamin D levels was greater during winter and months with fewer sunshine hours. Vitamin D levels did not vary according to age, sex, and disease. Individuals with obesity, hypertension, and osteoporosis were more likely to have low vitamin D levels compared with their healthy counterparts.

Conclusions: There is an alarmingly high rate of hypovitaminosis D and vitamin D deficiency among orthopaedic patients in this region of Germany, whose latitude (50° N) is approximately the same as those of Vancouver (49°, 15' N) and Paris (48°, 51' N). Given the well-known effects on bone metabolism and muscle health, low vitamin D levels may negatively affect patients. Screening and treating hypovitaminosis D appears to be important in this patient population.

Fig. 1

A graph shows the mean 25-OH-D level per month during 2011. During the summer months, the mean 25-OH-D level was 18.75 ng/mL, and during the darker 6 months of the year, the mean level was 16.1 ng/mL. The lowest 25-OH-D concentration occurred in November (13.7 ng/mL) and peak concentration occurred in July (22.35 ng/mL).

Fig. 2

A graph shows the correlation between mean sunshine hours per month and the mean 25-OH-D level, with higher 25-OH-D levels correlating with higher sunshine hours per month.