1. Sniadecki J: in Dziela (vol 1), Warsaw, 1840, pp 273-274

  2. Harris LJ: Vitamins in Theory and Practice, Cambridge, 1935, p 110

  3. McKenna MJ: Differences in vitamin D status between countries in young adults and the elderly. Am J Med 93:69-77, 1992

  4. Harris SS, Dawson-Hughes B: Seasonal changes in plasma 25-hydroxyvitamin D concentrations of young American black and white women. Am J Clin Nutr 67:1232-1236, 1998

  5. Harris SS, Soteriades E, Coolidge JA et al.: Vitamin D insufficiency and hyperparathyroidism in a low income, multiracial, elderly population. J Clin Endocrinol Metab 85:4125-4130, 2000

  6. Lebrun JB, Moffatt ME, Mundy RJ et al.: Vitamin D deficiency in a Manitoba community. Can J Public Health 84:394-396, 1993

  7. Gloth FM, III, Gundberg CM, Hollis BW et al.: Vitamin D deficiency in homebound elderly persons. JAMA 274:1683-1686, 1995

  8. Chapuy MC, Preziosi P, Maamer M et al.: Prevalence of vitamin D insufficiency in an adult normal population. Osteoporos Int 7:439-443, 1997

  9. Liu BA, Gordon M, Labranche JM et al.: Seasonal prevalence of vitamin D deficiency in institutionalized older adults. J Am Geriatr Soc 45:598-603, 1997

  10. Kinyamu HK, Gallagher JC, Rafferty KA, Balhorn KE: Dietary calcium and vitamin D intake in elderly women: effect on serum parathyroid hormone and vitamin D metabolites. Am J Clin Nutr 67:342-348, 1998

  11. Thomas MK, Lloyd-Jones DM, Thadhani RI et al.: Hypovitaminosis D in medical inpatients. N Engl J Med 338:777-783, 1998

  12. Bettica P, Bevilacqua M, Vago T, Norbiato G: High prevalence of hypovitaminosis D among free-living postmenopausal women referred to an osteoporosis outpatient clinic in northern Italy for initial screening. Osteoporos Int 9:226-229, 1999

  13. Waiters B, Godel JC, Basu TK: Perinatal vitamin D and calcium status of northern Canadian mothers and their newborn infants. J Am Coll Nutr 18:122-126, 1999

  14. Outila TA, Karkkainen MU, Lamberg-Allardt CJ: Vitamin D status affects serum parathyroid hormone concentrations during winter in female adolescents: associations with forearm bone mineral density. Am J Clin Nutr 74:206-210, 2001

  15. Kauppinen-Makelin R, Tahtela R, Loyttyniemi E et al.: A high prevalence of hypovitaminosis D in Finnish medical in- and outpatients. J Intern Med 249:559-563, 2001

  16. Lips P, Duong T, Oleksik A et al.: A global study of vitamin D status and parathyroid function in postmenopausal women with osteoporosis: baseline data from the multiple outcomes of raloxifene evaluation clinical trial. J Clin Endocrinol Metab 86:1212-1221, 2001

  17. Vieth R, Cole DE, Hawker GA et al.: Wintertime vitamin D insufficiency is common in young Canadian women, and their vitamin D intake does not prevent it. Eur J Clin Nutr 55:1091-1097, 2001

  18. Rucker D, Allan JA, Fick GH, Hanley DA: Vitamin D insufficiency in a population of healthy western Canadians. CMAJ 166:1517-1524, 2002

  19. Nesby-O’Dell S, Scanlon KS, Cogswell ME et al.: Hypovitaminosis D prevalence and determinants among African American and white women of reproductive age: third National Health and Nutrition Examination Survey, 1988-1994. Am J Clin Nutr 76:187-192, 2002

  20. Looker AC, Dawson-Hughes B, Calvo MS et al.: Serum 25-hydroxyvitamin D status of adolescents and adults in two seasonal subpopulations from NHANES III. Bone 30:771-777, 2002

  21. Isaia G, Giorgino R, Rini GB et al.: Prevalence of hypovitaminosis D in elderly women in Italy: clinical consequences and risk factors. Osteoporos Int 14:577-582, 2003

  22. Gessner BD, Plotnik J, Muth PT: 25-hydroxyvitamin D levels among healthy children in Alaska. J Pediatr 143:434-437, 2003

  23. Rockell JE, Green TJ, Skeaff CM et al.: Season and ethnicity are determinants of serum 25-hydroxyvitamin D concentrations in New Zealand children aged 5-14 y. J Nutr 135:2602-2608, 2005

  24. Hirani V, Primatesta P: Vitamin D concentrations among people aged 65 years and over living in private households and institutions in England: population survey. Age Ageing 34:485-491, 2005

  25. Holick MF, Siris ES, Binkley N et al.: Prevalence of Vitamin D inadequacy among postmenopausal North American women receiving osteoporosis therapy. J Clin Endocrinol Metab 90:3215-3224, 2005

  26. Zadshir A, Tareen N, Pan D et al.: The prevalence of hypovitaminosis D among US adults: data from the NHANES III. Ethn Dis 15:S5-101, 2005

  27. Wolf M, Shah A, Gutierrez O et al.: Vitamin D levels and early mortality among incident hemodialysis patients. Kidney Int 72:1004-1013, 2007

  28. Ginde AA, Liu MC, Camargo CA, Jr.: Demographic differences and trends of vitamin D insufficiency in the US population, 1988-2004. Arch Intern Med 169:626-632, 2009

  29. Brot C, Vestergaard P, Kolthoff N et al.: Vitamin D status and its adequacy in healthy Danish perimenopausal women: relationships to dietary intake, sun exposure and serum parathyroid hormone. Br J Nutr 86 Suppl 1:S97-103, 2001

  30. Jacob AI, Sallman A, Santiz Z, Hollis BW: Defective photoproduction of cholecalciferol in normal and uremic humans. J Nutr 114:1313-1319, 1984

  31. Levin A, Bakris GL, Molitch M et al.: Prevalence of abnormal serum vitamin D, PTH, calcium, and phosphorus in patients with chronic kidney disease: results of the study to evaluate early kidney disease. Kidney Int 71:31-38, 2007

  32. Holick MF: Vitamin D deficiency. N Engl J Med 357:266-281, 2007

  33. DeLuca HF: Overview of general physiologic features and functions of vitamin D. Am J Clin Nutr 80:1689S-1696S, 2004

  34. Lin R, White JH: The pleiotropic actions of vitamin D. Bioessays 26:21-28, 2004

  35. Dobnig H, Pilz S, Scharnagl H et al.: Independent association of low serum 25-hydroxyvitamin d and 1,25-dihydroxyvitamin d levels with all-cause and cardiovascular mortality. Arch Intern Med 168:1340-1349, 2008

  36. Ng K, Meyerhardt JA, Wu K et al.: Circulating 25-hydroxyvitamin d levels and survival in patients with colorectal cancer. J Clin Oncol 26:2984-2991, 2008

  37. Zhou W, Heist RS, Liu G et al.: Circulating 25-hydroxyvitamin D levels predict survival in early-stage non-small-cell lung cancer patients. J Clin Oncol 25:479-485, 2007

  38. Melamed ML, Michos ED, Post W, Astor B: 25-hydroxyvitamin D levels and the risk of mortality in the general population. Arch Intern Med 168:1629-1637, 2008

  39. Ravani P, Malberti F, Tripepi G et al.: Vitamin D levels and patient outcome in chronic kidney disease. Kidney Int 75:88-95, 2009

  40. Mehrotra R, Kermah DA, Salusky IB et al.: Chronic kidney disease, hypovitaminosis D, and mortality in the United States. Kidney Int 76:977-983, 2009

  41. Kovesdy CP, Ahmadzadeh S, Anderson JE, Kalantar-Zadeh K: Association of activated vitamin D treatment and mortality in chronic kidney disease. Arch Intern Med 168:397-403, 2008

  42. Shoji T, Shinohara K, Kimoto E et al.: Lower risk for cardiovascular mortality in oral 1alpha-hydroxy vitamin D3 users in a haemodialysis population. Nephrol Dial Transplant 19:179-184, 2004

  43. Teng M, Wolf M, Ofsthun MN et al.: Activated injectable vitamin D and hemodialysis survival: a historical cohort study. J Am Soc Nephrol 16:1115-1125, 2005

  44. Tentori F, Hunt WC, Stidley CA et al.: Mortality risk among hemodialysis patients receiving different vitamin D analogs. Kidney Int 70:1858-1865, 2006

  45. Kalantar-Zadeh K, Kuwae N, Regidor DL et al.: Survival predictability of time-varying indicators of bone disease in maintenance hemodialysis patients. Kidney Int 70:771-780, 2006

HOW TO TAKE THE POST-TEST: To obtain CME credit, please click here after reading the article to take the post-test on