* Essential hypertension accounts for 90% of cases of hypertension in adults.
* Secondary causes of hypertension account for the remaining 10% of cases of
chronically elevated BP. These include the following:

* Renal causes

– Renal artery stenosis
– Polycystic kidney disease
– Chronic renal failure
– Intrarenal Vasculitis

* Endocrine causes

– Primary hyperaldosteronism
– Pheochromocytoma
– Cushing syndrome
– Congenital adrenal hyperplasia
– Hypothyroidism and hyperthyroidism
– Acromegaly
– Exogenous hormone (eg, corticosteroids, estrogens), sympathomimetics,
monoamine oxidase inhibitors (MAOIs), and tyramine-containing foods

* Others

– Coarctation of aorta
– Raised intracranial pressure
– Sleep apnea
– Isolated systolic hypertension – Can be observed in elderly people, due
to increased stiffness of the vasculature
– Isolated systolic hypertension – Can be observed in thyrotoxicosis,
atrioventricular (AV) fistula, aortic regurgitation, beriberi, Paget
disease, and patent ductus arteriosus (ie, due to increase cardiac
output secondary to a hyperdynamic circulation)