Chronic hypertension classification

Hypertension Main page
Overview
Causes
Classification Primary Hypertension Secondary Hypertension Hypertensive Emergency Hypertensive Urgency
Screening

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Assistant Editor-In-Chief: Taylor Palmieri

Overview

The Joint National Committee seventh report (JNC 7) defines hypertension as a systolic blood pressure of over 140 mm Hg or a diastolic blood pressure greater than 90 mm Hg based upon the average of two or more properly measured readings at each of two or more visits after an initial screen:

JNC Classification of Severity

The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure has classified blood pressure in the follows:

Blood Pressure Classification	Systolic (mm Hg)		Diastolic (mm Hg)
Normal	< 120	and	< 80
Pre-Hypertension	120-139	or	80-89
Stage 1 Hypertension	140-159	or	90-99
Stage 2 Hypertension	>160	or	>100

Prehypertension is not a disease category; rather, it is a designation chosen to identify individuals at high risk of developing hypertension. It is not clear if treatment of pre-hypertension would improve outcomes. In patients with diabetes mellitus or kidney disease, a blood pressure > 130/80 mmHg should be considered elevated and may warrant treatment.

Classification of Pathophysiology

Once the diagnosis of hypertension has been made it is important to attempt to exclude or identify reversible (secondary) causes.

• Over 90% of adult hypertension has no clear cause and is therefore called essential/primary hypertension. Often, it is part of the metabolic "syndrome X" in patients with insulin resistance: it occurs in combination with diabetes mellitus (type 2), combined hyperlipidemia and central obesity.
• Secondary hypertension is more common in pre-adolescent children, with most cases caused by renal disease.

Essential Hypertension

Essential hypertension is the most prevalent type of hypertension type, and affects 90-95% of hypertensive patients. Although there are risk factors for essential hypertension (sedentary lifestyle, obesity, increased salt intake, increased alcohol intake), by defintion there is no other disease state responsible for the occurrence of the elevated blood pressure.

Secondary hypertension

Secondary hypertension results from an identifiable cause. Recognition of secondary hypertension is critical since the management is different than primary or essential hypertension and involves treatment of the underlying cause of the elevated blood pressure. Underlying disorders that account for secondary hypertension include:

• Acromegaly
• Chronic kidney disease
• Coarctation of the aorta
• Cushing's syndrome due to an excessive secretion of glucocorticoids which in turn causes the hypertension
• Drugs:

• Adrenoceptor stimulants
• Monoamine oxidase inhibitors (MAOI)s
• Nasal decongestants with adrenergic effects
• NSAIDs
• Oral contraceptives
• Steroids

• Fever
• Hyperaldosteronism (Conn's syndrome):

• Idiopathic hyperaldosteronism
• Liddle's syndrome (also called pseudoaldosteronism)
• Glucocorticoid remediable aldosteronism

• Hyperparathyroidism
• Hyperthyroidism
• Hypothyroidism
• Liquorice
• Neurofibromatosis
• Obstructive sleep apnea
• 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.
• Pheochromocytoma: Caused by an excessive secretion of norepinephrine and epinephrine which promotes vasoconstriction. Consider this diagnosis in the patient who has a dilated cardiomyopathy (which a pheochromocytoma can cause) who still has an elevated blood pressure.
• Pregnancy
• 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.
• Scleroderma
• White coat hypertension