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| ==Overview== | | ==Overview== |
| The most common cause of hypertension in 90% of cases is [[essential hypertension]] where no clear identifying underlying cause can be identified, and the [[Hypertension pathophysiology|pathophysiology]] of which is incompletely understood. There are many secondary causes of hypertension.
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| ==The Most Common Cause== | | ==Causes== |
| The most common cause of hypertension is [[essential hypertension]] which accounts for about 90% of cases of elevated blood pressure.
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| ==Common Causes of Secondary Hypertension<ref>isbn=140510368X Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:85</ref><ref>isbn=1591032016 Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:194-195</ref>==
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| In only a small minority of patients with elevated arterial pressure can a specific cause be identified. An underlying [[endocrine]] or renal defect is most often identified, that if corrected, may restore the blood pressure back to normal.
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| ===When to Suspect Secondary Hypertension===
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| A secondary cause of hypertension should be suspected if the patient has [[resistant hypertension]]. The AHA Scientific Statement 2008 defines resistant hypertension as a blood pressure which remains above the goal of 140/90 mm Hg despite concurrent use of 3 antihypertensive medications of different classes at optimal doses, including a diuretic.<ref name="pmid18391085">{{cite journal| author=Calhoun DA, Jones D, Textor S, Goff DC, Murphy TP, Toto RD et al.| title=Resistant hypertension: diagnosis, evaluation, and treatment. A scientific statement from the American Heart Association Professional Education Committee of the Council for High Blood Pressure Research. | journal=Hypertension | year= 2008 | volume= 51 | issue= 6 | pages= 1403-19 | pmid=18391085 | doi=10.1161/HYPERTENSIONAHA.108.189141 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18391085 }} </ref>.
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| Other features that suggest secondary hypertension include:
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| *Recent onset of hypertension
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| *Unprovoked [[hypokalemia]] or an inappropriately [[low potassium]] (e.g. a "normal K" on an [[ACE inhibitor]] plus a [[K sparing diuretic]])
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| *Presence of [[peripheral arterial disease]]
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| *Increase in [[creatine]] with [[ACE inhibition]]
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| *Loss of control of previously controlled hypertension
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| Before evaluating the patient for secondary hypertension, non-compliance with antihypertensives should be ruled out. Given its prevalence in the Unites States population, sleep apnea should also be ruled out early in the evaluation.
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| ===Common Causes of Secondary Hypertension===
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| Common causes of secondary hypertension include:
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| * [[Anxiety]]: Hypertension is often confused with mental tension, stress and [[anxiety]]. While chronic anxiety is associated with poor outcomes in people with hypertension, it alone probably does not cause it.
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| * [[Arteriosclerosis]]
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| * [[Chronic kidney disease]]. This includes diseases such as [[polycystic kidney disease]] or chronic [[glomerulonephritis]].
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| * [[Congenital adrenal hyperplasia]]
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| * [[Cushing's syndrome]] due to an excessive secretion of [[glucocorticoids]] which in turn causes the hypertension
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| * Drugs:
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| :*[[Nasal decongestants]] with adrenergic effects
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| :*[[NSAIDs]]
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| :*[[Oral contraceptives]]
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| :*[[Steroids]]
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| * [[Fever]]
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| * [[Hyperaldosteronism]] ([[Conn's syndrome]]): Hypertension is a feature of a variety of adrenal cortical abnormalities. In primary [[aldosteronism]] there is a clear relationship between the aldosterone-induced sodium retention and the hypertension. Suspect hyperaldosteronism if the patient has an unusual sensitivity to a diuretic in causing [[hypokalemia]], if there is frequent hypokalemia, and if there is a normal potassium in the setting of ACE inhibition with a potassium spairing diuretic. The [[plasma renin activity]] is suppressed and there is elevated [[aldosterone]] on [[adrenal vein]] sampling.
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| :*[[Idiopathic hyperaldosteronism]]
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| :*[[Liddle's syndrome]] (also called [[pseudoaldosteronism]])
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| :*[[Glucocorticoid remediable aldosteronism]]
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| * [[Hyperthyroidism]]
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| * [[Hypothyroidism]]
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| * [[Increased salt intake]]
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| * [[Metabolic syndrome]]
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| * Non-compliance with antihypertensives
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| * [[Obesity]]
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| * [[Obstructive sleep apnea]] can cause a rise in [[catecholamines]]
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| * Perioperative hypertension: this is the development of hypertension just before, during or after surgery. It may occur before surgery during the induction of anesthesia; intraoperatively e.g. by pain-induced [[sympathetic nervous system]] stimulation; in the early postanesthesia period, e.g. by pain-induced [[sympathetic stimulation]], [[hypothermia]], [[hypoxia]], or hypervolemia from excessive intraoperative fluid therapy; and in the 24 to 48 hours after the postoperative period as fluid is mobilized from the extravascular space. In addition, hypertension may develop perioperatively because of discontinuation of long-term antihypertensive medication.
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| * [[Pheochromocytoma]]: Caused by an excessive secretion of norepinephrine and epinephrine which promotes vasoconstriction. Consider this diagnosis in the patient who has [[headaches]], [[diaphoresis]], [[palpitations]], [[orthostatic hypotension]], hypertension with anesthesia induction and those patients with a [[dilated cardiomyopathy]] (which a [[pheochromocytoma]] can cause) who still have an elevated [[blood pressure]] despite a loss in [[cardiac output]]. This diagnosis is confirmed by demonstrating increased urinary excretion of epinephrine and norepinephrine and/or their metabolites ([[vanillylmandelic acid]]).
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| * [[Pregnancy]] causing [[gestational hypertension]]
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| * [[Renovascular hypertension]]: Due to [[fibromuscular dysplasia]] and [[renal artery stenosis]]. In both conditions, increased blood pressure occurs due to narrowing of arteries supplying to the kidney. Decreased perfusion of renal tissue due to [[stenosis]] of a main or branch renal artery activates the [[renin-angiotensin system]].
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| :Tests to Assess for Renovascular Hypertension
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| :*Renal Ultrasound: Look for a difference in the size of kidneys
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| :*CT: Although there is a dye load, there is no Gadollinium which can be toxic with an MRI, the images are better than MRI
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| :*Indications for Arteriographic Imaging to Rule Out Renovascular Hypertension<ref>J Vasc Interv Rad 2006 17:1383-1398</ref>
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| ::Class I
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| :::*Hypertension in a patient < 30 yrs old
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| :::*Severe increase in blood pressure in a patient > 55 yrs old
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| :::*Accelerated increase in BP
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| :::*Resistant increase in BP
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| :::*Complicated malignant increase in BP
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| :::*Reduction in [[GFR]] or rise in Cr with [[RAS]] blockade
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| :::*> 1.5 cm difference in renal size on ultrasound
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| :::*Flash pulmonary edema
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| ::Class IIa
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| :::*Unexplained [[renal failure]]
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| ::Class IIb
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| :::*Multivessel [[CAD]] or [[PAD]]
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| :::*Unexplained [[CHF]] or refractory angina
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| * [[Scleroderma]]
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| * [[Stress]]
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| * [[White coat hypertension]]
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| ==Common Causes of Resistant Hypertension<ref name="pmid12748199">{{cite journal| author=Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo JL et al.| title=The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report. | journal=JAMA | year= 2003 | volume= 289 | issue= 19 | pages= 2560-72 | pmid=12748199 | doi=10.1001/jama.289.19.2560 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12748199}}</ref>==
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| *'''Improper blood pressure measurement'''
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| *'''Volume overload'''
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| **Excess sodium intake
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| **Volume retention from kidney disease
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| **Inadequate [[diuretic]] therapy
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| *'''Drug-induced or other causes'''
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| **Non-adherence
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| **Inadequate doses
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| **Inappropriate combinations
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| **[[NSAIDs]], COX inhibitors
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| **[[Cocaine]], [[amphetamines]], other illicit drugs
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| **Sympathomimetics (decongestants, anorectics)
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| **[[Oral contraceptive therapy]]
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| **Adrenal steroid hormones
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| **[[Cyclosporine]], [[tacrolimus]]
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| **[[Erythropoietin]]
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| **[[Licorice]] (including some chewing [[tobacco]])
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| **Selected over the counter dietary supplements (like ephedra, ma huang, bitter orange)
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| ==Less Common Causes==
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| * [[Acromegaly]]
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| * [[Coarctation of the aorta]]
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| * [[Hyperparathyroidism]]
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| * [[Liquorice]] (black, not red). Drives up cortisol causing a Cushing-like syndrome.
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| * [[Neurofibromatosis]]
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| ==Complete List of Causes by Organ System== | | ==Complete List of Causes by Organ System== |