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International Journal of Endocrinology
Volume 2016, Article ID 6836402, 7 pages
http://dx.doi.org/10.1155/2016/6836402
Clinical Study

Vitamin D Supplementation and Hemoglobin Levels in Hypertensive Patients: A Randomized Controlled Trial

1Clinic for Thoracic and Cardiovascular Surgery, Heart and Diabetes Center NRW, Ruhr University Bochum, Georgstraße 11, 32545 Bad Oeynhausen, Germany
2Department of Cardiology, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria
3Specialist Clinic for Rehabilitation Bad Aussee, Braungasse 354, 8990 Bad Aussee, Austria
4Department of Cardiology, Charité University, Campus Virchow, Augustenburger Platz 1, 13353 Berlin, Germany
5Department of Internal Medicine, Division of Endocrinology and Metabolism, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria
6Swiss Cardiovascular Center Bern, Department of Cardiology, Bern University Hospital, 3007 Bern, Switzerland
7Medical Clinic V (Nephrology, Hypertensiology, Endocrinology, Diabetology, Rheumatology) Mannheim Medical Faculty, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
8Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Auenbruggerplatz 15, 8036 Graz, Austria
9Synlab Academy, Synlab Laboratory Services GmbH, P5, 7, 68161 Mannheim, Germany
10Department of Epidemiology and Biostatistics, EMGO Institute for Health and Care Research, VU University Medical Center, Van der Boechorststraat 7, 1081 BT Amsterdam, Netherlands

Received 6 January 2016; Accepted 31 January 2016

Academic Editor: Andre P. Kengne

Copyright © 2016 Jana B. Ernst et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Epidemiological evidence suggests that circulating 25-hydroxyvitamin D (25OHD) levels are inversely associated with hemoglobin (Hb) levels and anemia risk. We evaluated whether vitamin D supplementation improves Hb levels and reduces anemia risk in hypertensive patients. Two hundred patients with 25OHD levels <75 nmol/L who attended the Styrian Vitamin D Hypertension Trial were included, of whom 188 completed the trial. Patients randomly received 2800 IU vitamin D3 daily or a matching placebo for eight weeks. Initially, the prevalence of anemic status (Hb levels <12.5 g/dL) and deficient 25OHD levels (<30 nmol/L) was 6.5% and 7.5%, respectively. All anemic patients had 25OHD levels >50 nmol/L. The mean (95% confidence interval) vitamin D effect on Hb levels was 0.04 (−0.14 to 0.22) g/dL (). Moreover, vitamin D treatment did not influence anemic status significantly (). Likewise, vitamin D had no significant effect on Hb levels in the subgroups of anemic patients or in patients with initial 25OHD levels <30 nmol/L. In conclusion, a daily vitamin D supplement of 2800 IU for eight weeks did not improve Hb levels or anemic status in hypertensive patients. Future trials should focus on anemic patients with deficient 25OHD levels (e.g., <30 nmol/L). This trial is registered with clinicaltrials.gov [NCT02136771].