Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. CONCISE COMMUNICATION Efavirenz is associated with severe vitamin D deficiency and increased alkaline phosphatase Tanya Welz a , Kate Childs a , Fowzia Ibrahim c , Mary Poulton a , Chris B. Taylor a , Caje F. Moniz b and Frank A. Post a,c Objective(s): To identify factors (including exposure to specific antiretroviral drugs) associated with severe vitamin D deficiency (VDD) in HIV-infected individuals and to explore the effects of severe VDD and antiretroviral drug exposure on serum alkaline phosphatase (ALP) as surrogate marker of bone turnover. Design: Cross-sectional survey of vitamin D status among HIV-infected patients attending for routine clinical care at a large London HIV clinic. Methods: Severe VDD was defined as 25(OH)D levels of less than 10 mg/l (<25 nmol/l). Multivariate logistic regression analysis was used to identify factors associated with severe VDD and upper quartile ALP levels. Results: Vitamin D levels were measured in 1077 patients and found to be suboptimal in 91%. One-third of patients had severe VDD. Black ethnicity, sampling in winter, nadir CD4 cell count less than 200 cells/ml, and exposure to combination antiretroviral therapy were associated with severe VDD. In analyses restricted to patients on combination antiretroviral therapy, current efavirenz use was significantly associated with severe VDD [adjusted odds ratio 2.0 (95% confidence interval 1.5–2.7)]. Current tenofovir [adjusted odds ratio 3.5 (95% confidence interval 2.3 – 5.2)] and efavirenz use [adjusted odds ratio 1.6 (95% confidence interval 1.02 – 2.4)], but not severe VDD [odds ratio 1.1 (0.8 – 1.5)], were associated with increased bone turnover (upper quartile ALP). Conclusion: Efavirenz was associated with severe VDD, a condition associated with multiple adverse health outcomes, and efavirenz and tenofovir with increased ALP. The clinical significance of these findings requires further investigation, given the wide- spread use of efavirenz and tenofovir in first-line combination antiretroviral therapy. ß 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins AIDS 2010, 24:1923–1928 Keywords: alkaline phosphatase, antiretroviral therapy, bone, efavirenz, HIV, tenofovir, vitamin D Introduction Vitamin D, in its biologically active form calcitriol (1,25(OH) 2 D), plays an important role in calcium homeostasis, regulation of bone turnover, innate immune function, cell proliferation, and cell differentiation [1]. Vitamin D deficiency (VDD) has been associated with numerous adverse health outcomes, including rickets, a Department of HIV/Genitourinary Medicine, b Department of Clinical Biochemistry, King’s College Hospital, and c King’s College London School of Medicine, London, UK. Correspondence to Dr Frank A. Post, Clinical Senior Lecturer, King’s College London School of Medicine, Weston Education Centre (Rm 2.53), Cutcombe Road, London SE5 9RJ, UK. E-mail: frank.post@kcl.ac.uk Received: 5 February 2010; revised: 1 May 2010; accepted: 14 May 2010. DOI:10.1097/QAD.0b013e32833c3281 ISSN 0269-9370 Q 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins 1923