Vitamin D Insufficiency

The author reviews data supporting the recommendation to maintain a serum concentration of vitamin D above 20 ng per milliliter and notes the lack of evidence to support a higher target level. He reviews the limitations of data linking vitamin D insufficiency to chronic disease risk. Foreword This Journal feature begins with a case vignette highlighting a common clinical problem. Evidence supporting various strategies is then presented, followed by a review of formal guidelines, when they exist. The article ends with the author's clinical recommendations. Stage A healthy 61-year-old white woman is concerned about a low vitamin D level detected during an assessment of her skeletal health. Her menopause began at 54 years of age. She has no history of falls, and there is no family history of hip fracture. She takes no medications or supplements. Her height is 157.5 cm (5 ft 2 in.), and her weight 59.1 kg (130 lb). The results of a physical examination are unremarkable, and the findings on laboratory studies are normal. The T score for bone mineral density at the hip is −1.5, and the serum level of . . .