Approximately 90% of hypertension is idiopathic and it is specifically seen as primary (essential) hypertension. 10% of the rest is secondary for most renal diseases and coarctation of the renal artery (renovascular hypertension) which is generally caused by an atheroma plaque. Secondary hypertension develops as a result of primary aldosteronism at a low rate, and some surrenal disorders such as Cushing’s syndrome and feochromositoma.
Secondary hypertension is elevated blood pressure that results from an underlying, identifiable, often correctable cause. The prevalence of secondary hypertension is around 5-6% of all hypertensives. Because of low prevalence, routine screening for secondary hypertension is not essential and cost effective. Renal disease constitutes the major group of secondary hypertension.
Hypertension, after diabetes mellitus, is the second leading cause of end-stage renal disease (ESRD) and together these entities account for over 60% of ESRD patients.
Essential hypertension is characterized by a sustained systolic pressure of greater than 140 mm Hg and a diastolic BP at greater than 90 mm Hg. The pathophysiology of essential hypertension depends on the primary or secondary inability of the kidney to excrete sodium at a normal blood pressure. The central nervous system, endocrine factors, the large arteries, and the microcirculation also have roles in the disorder.
Primary and secondary hypertension
