Influence of season, ethnicity, and chronicity on vitamin D deficiency in traumatic spinal cord injury.
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.


OBJECTIVE
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.


METHODS
Patients (N=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) (<32 ng/mL). Lower vitamin D25(OH) levels were observed in African Americans relative to whites. Significant main effects were noted for season (P = 0.017), chronicity (P = 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.
Oleson
Christina V
CV
Department of Rehabilitation Medicine, Birmingham School of Medicine, University of Alabama at Birmingham, Alabama, USA. christina.oleson@jefferson.edu
Patel
Payal H
PH
Wuermser
Lisa-Ann
LA
D000328:Adult; D000704:Analysis of Variance; D002118:Calcium / Q000097:blood; D002908:Chronic Disease; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D012621:Seasons; D013119:Spinal Cord Injuries / Q000097:blood* / Q000208:ethnology*; D013997:Time Factors; D014807:Vitamin D / Q000097:blood*; D055815:Young Adult
D010281:Parathyroid Hormone; D014807:Vitamin D; D002118:Calcium