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To the Editor: Several factors affect serum 25-hydroxyvitamin D concentration, including age, smoking, renal function, adiposity, and body weight or body mass index.¹ Furthermore, several conditions may affect the bioavailability of study participants' calcium supplementation, such as dosing with or without meals, the form of calcium supplement taken, the dosage taken at one time (>600 mg), coadministration with proton pump inhibitors, and vitamin D status.² In the study of serum parathyroid hormone (PTH) levels, vitamin D sufficiency, and calcium intake by Dr Steingrimsdottir and colleagues,³ it is not clear if these factors have been considered.

Vitamin D is considered an important determinant of bone health because its use as a supplement has been shown to reduce the risk of falls as well as hip and nonvertebral fractures in older persons.⁴ Twelve hundred milligrams per day has been suggested as the recommended calcium intake for elderly persons, but calcium intake of . . . [Full Text of this Article]

Jen-Tzer Gau, MD, PhD
gau@exchange.oucom.ohiou.edu
Department of Geriatric Medicine/Gerontology

Steven Clay, DO
Department of Family Medicine

Wayne Carlsen, DO
Department of Geriatric Medicine/Gerontology
College of Osteopathic Medicine
Ohio University
Athens

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