Influence of Season, Ethnicity, and Chronicity on Vitamin D Deficiency in Traumatic Spinal Cord Injury

Abstract

Background: Inadequate levels of vitamin D increase the risk of osteoporosis, a highly prevalent condition in patients with traumatic spinal cord injury (SCI). Reduced sunlight and dark skin further contribute to low vitamin D levels. Objectives: To compare serum 25-hydroxy vitamin D [vitamin D25(OH)] levels in acute and chronic SCI and to explore seasonal and ethnic differences among patients with acute and chronic SCI. Patients/Methods: Patients (N 5 96) aged 19 to 55 years with C3-T10 motor complete SCI participated. Acute SCI was 2 to 6 months after injury, whereas chronic SCI was at least 1 year from injury. Serum vitamin D25(OH), calcium, and parathyroid hormone were drawn during summer or winter months. Vitamin D deficiency (,13 ng/mL), insufficiency (,20 ng/mL), and subtherapeutic (,32 ng/mL) levels were compared for all groups. A 3-way analysis of covariance was adopted to determine significant main effects of season, chronicity, and ethnicity. Interactions between season and chronicity, season and ethnicity, and chronicity and ethnicity were evaluated. Evaluation of a 3-way interaction among season, chronicity, and ethnicity was completed. Results: In summer, 65% of patients with acute SCI and 81% of patients with chronic SCI had subtherapeutic vitamin D levels, whereas in winter, 84% with acute SCI and 96% with chronic SCI had vitamin D25(OH) (,32ng/mL). Lower vitamin D25(OH) levels were observed in African Americans relative to whites. Significant main effects were noted for season (P 5 0.017), chronicity (P 5 0.003), and ethnicity (P , 0.001). However, interactions between 2 or more factors were not found. Conclusions: Vitamin D insufficiency and deficiency are found in the majority of patients with chronic SCI and in many with acute SCI. Initial screening for serum vitamin D25(OH) levels should be performed early in rehabilitation. Periodic monitoring in the chronic setting is highly recommended.

Association of vitamin D deficiency, secondary hyperparathyroidism, and heterotopic ossification in spinal cord injury

“…Moreover, we believe that maintaining vitamin D levels in the normal range of 32 ng/mL is most desirable not only for HO prevention but also for many secondary health benefits as described in our previous work [10]. The current findings also suggest that keeping PTH within the normal range may prevent HO formation in the population with SCI.…”

“…In looking at the calcium levels of subjects in our study, all were within the reference range of 8.5 to 10.5 mEq/dL set by our clinical laboratory [10]. It appears that the role of PTH and its interactions with proteins expressed in the posttraumatic setting, such as bone morphogenic protein (BMP), contribute more to the development of HO than do calcium levels alone.…”

“…Of the 96 subjects who participated in our previous study [10] on the presence of vitamin D deficiency, 12 reported HO as verified by review of the medical record, including imaging studies either at the institution of care or at an outside hospital. Of the 78 subjects with low vitamin D (<32 ng/mL), 11 demonstrated HO formation.…”

“…In these reports, PTH levels did not demonstrate upregulation unless serum vitamin D25(OH) levels were <20 ng/mL, suggesting that perhaps therapeutic values for this group have a lower limit of 20 ng/mL (range: 20-100 ng/mL) instead of 32 ng/mL (range: 32-100 ng/mL). Since hyperparathyroidism develops as a secondary effect to low vitamin D, it is appropriate to look at our chronic subjects in terms of our previous work [10]. However, we are unable to give clinical data to support the lack of complications in this borderline range of serum vitamin D in African Americans with chronic SCI, simply because 92.3 percent of subjects had levels less than 20 ng/mL, with just one subject between 20 and 31 ng/mL and one subject with 32 mg/ mL.…”

“…Our group has recently completed an observational study of vitamin D levels in 42 subjects with acute SCI, defined as 2 to 6 mo postinjury, and 54 subjects with chronic SCI, defined as >1 yr postinjury [10]. A high percentage of subjects with deficient levels of vitamin D exhibited HO in bones below the neurological level of injury.…”