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Vitamin D Levels in Elders

Most older people had low serum levels, and at least 25% of elders had frank vitamin D deficiency.

Two studies in the Journal of Clinical Endocrinology and Metabolism focus on vitamin D in older populations.

Researchers measured serum 25-hydroxyvitamin D (25[OH]D) in 6000 community-dwelling men (age range, 65–99) who lived in various U.S. regions. Average serum 25(OH)D level was 25 ng/mL; one quarter of subjects had levels lower than 20 ng/mL. In multivariable analysis, lower 25(OH)D levels were associated with older age, obesity, black or Latino ethnicity, blood sampling in winter, and residence at a northern latitude (e.g., Minneapolis, compared with San Diego). Use of vitamin D supplements and engaging in outdoor activities were associated with higher vitamin D levels.

Dutch researchers examined relations between vitamin D levels and bone metabolism in 1300 randomly selected older adults (age range, 65–88). Mean serum 25(OH)D level was 21 ng/mL; half the participants had levels lower than 20 ng/mL. Findings included the following:

• Serum parathyroid hormone levels were inversely proportional to vitamin D levels, without any plateau effect.
  
• Markers of bone turnover (serum osteocalcin and urinary deoxypyridinoline) were inversely proportional to 25(OH)D levels until the latter exceeded 20 ng/mL; above that point, bone turnover markers plateaued.
  
• Total hip bone-mineral density was directly proportional to 25(OH)D levels until the latter exceeded 20 ng/mL; above that point, bone density plateaued.
  

Comment: Average vitamin D levels were similar in both of these studies in older people. The factors that predisposed elders to vitamin D deficiency in the U.S. study have been recognized previously in younger populations. The Dutch results suggest that bone metabolism is affected adversely when 25(OH)D levels drop below a threshold of about 20 ng/mL. This finding supports 20 ng/mL as a reasonable cutoff for a designation of vitamin D deficiency.

— Allan S. Brett, MD

Published in Journal Watch General Medicine April 23, 2009

Citation(s):

Orwoll E et al. Vitamin D deficiency in older men. J Clin Endocrinol Metab 2009 Apr; 94:1214.

• Original article (Subscription may be required)
• Medline abstract (Free)

Kuchuk NO et al. Relationships of serum 25-hydroxyvitamin D to bone mineral density and serum parathyroid hormone and markers of bone turnover in older persons. J Clin Endocrinol Metab 2009 Apr; 94:1244.

• Original article (Subscription may be required)
• Medline abstract (Free)

Reader Remarks:

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• SCREENING FOR VITAMIN D
  JL Brown, 24 Apr 2009 12:58 PM EST
  Should we know the vitamin D levels of elderly patients? Who will pay for this screening?
• Vitamin D Levels Seem, Generally, Unwarranted
  E Chamberlain MD, 26 Apr 2009 1:54 PM EST
  Seems we should assume a degree of Vitamin D deficiency (relative or absolute) and forego routine primary screening and simply... [more]
• Vitamin D deficiency
  Ann I. Pollock, 26 Apr 2009 1:54 PM EST
  The patient should be responsible for screening test. If they have insurance that assists them, great. If not, they have... [more]
• Vitamin D Screening and Supplementation
  Sandra E Murphy, Primary Care Clinic, 29 May 2009 2:23 PM EST
  Frankly supplementation with 400-800IU Vit D3 is useless. If there is even a suspicion of deficiency, 4000IU and higher are... [more]
• vitamin D deficiency occurs at >> 20 ng/mL.
  D P Poulter, 15 Jun 2009 4:28 PM EST
  It is unlikely any single study is going to provide adequately comprehensive information on this subject to manage dosing members... [more]