SAGE-Hindawi Access to Research International Journal of Hypertension Volume 2011, Article ID 236239, 17 pages doi:10.4061/2011/236239 Review Article Common Secondary Causes of Resistant Hypertension and Rational for Treatment Charles Faselis,1 Michael Doumas,1 and Vasilios Papademetriou2 1 Veterans Aﬀairs Medical Center, George Washington University, VAMC 50 Irving Street NW, Washington, DC 20422, USA 2 Veterans Aﬀairs Medical Center, Georgetown University, Washington, DC 20422, USA Correspondence should be addressed to Charles Faselis, charles.faselis@med.va.gov Received 8 November 2010; Accepted 11 January 2011 Academic Editor: Konstantinos Tsiouﬁs Copyright © 2011 Charles Faselis 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. Resistant hypertension is deﬁned as uncontrolled blood pressure despite the use of three antihypertensive drugs, including a diuretic, in optimal doses. Treatment resistance can be attributed to poor adherence to antihypertensive drugs, excessive salt intake, physician inertia, inappropriate or inadequate medication, and secondary hypertension. Drug-induced hypertension, obstructive sleep apnoea, primary aldosteronism, and chronic kidney disease represent the most common secondary causes of resistant hypertension. Several drugs can induce or exacerbate pre-existing hypertension, with non-steroidal anti-inﬂammatory drugs being the most common due to their wide use. Obstructive sleep apnoea and primary aldosteronism are frequently encountered in patients with resistant hypertension and require expert management. Hypertension is commonly found in patients with chronic kidney disease and is frequently resistant to treatment, while the management of renovascular hypertension remains controversial. A step-by-step approach of patients with resistant hypertension is proposed at the end of this review paper. 1. Introduction Hypertension represents a major public health problem aﬀecting more than one billion individuals worldwide [1]. The advent of antihypertensive therapy has substantially reduced the occurrence of cardiovascular events. However, antihypertensive therapy failed to achieve blood pressure control in all patients, with hypertension control rates remaining in general disappointingly low. Blood pressure goals are not attained in some patients despite the simulta- neous use of several antihypertensive medications. Several terms have been used to deﬁne this condition: “refractory hypertension”, “diﬃcult-to-treat hypertension”, “diﬃcult-to- control hypertension”; however, the term “resistant hyper- tension” seems to prevail. Resistant hypertension is currently deﬁned as uncon- trolled blood pressure despite the use of optimal doses of three antihypertensive medications, of which one is a diuretic [2]. Several factors have been identiﬁed as contributors to resistant hypertension. Poor patient adherence, physician inertia, inadequate doses or inappropriate combinations of antihypertensive drugs, excess alcohol intake, and volume overload are some of the most common causes of resistance [2–10]. Secondary forms of hypertension represent another very important contributor to drugresistance. The list of secondary forms of hypertension is long and covers a large variety of conditions (Table 1). Most of these conditions may result in resistance to pharmacologic therapy of hyperten- sion. The management of patients with resistant hyperten- sion requires a gratifying combination of clinical acumen and common sense. An extensive workup of all patients with uncontrolled hypertension is scientiﬁcally unsound, is very costly and requires immense human and technical resources. Therefore, practicing physicians need to imple- ment evidence-based medicine. The eﬀective management of patients with resistant hypertension requires an appro- priate combination of physiology and pharmacology, taking into account the unique characteristics of each case in order to tailor the therapeutic approach to the individual patient. This paper will address the most common secondary causes of resistant hypertension (drug-induced, obstructive sleep apnea, primary aldosteronism, and chronic kidney