Where does primary hypertension really begin?

Abstract

Classically hypertension is classified into primary and secondary. It is called primary when blood pressure is high without any apparent cause and secondary when a potentially treatable cause is detected. While secondary hypertension could also be endocrine in origin, the majority of cases of secondary hypertension are due to diseases of the  kidneys and renal vasculature. Therefore it is evident that altered renal physiology is central in genesis of secondary hypertension.

What, then, causes primary hypertension? Because no single cause has yet been identified as the cause of primary hypertension,  aetiopathogenesis of primary hypertension has traditionally been linked to various risk factors that are thought to cross interact with each other and lead to sustained elevation in blood pressure. Sedentary lifestyle, ethanol overuse, tobacco smoking, obesity, genetic predisposition,  and excessive intake of junk food are some of these risk factors.

It is well known that investigations of pathomechanisms related to increase in blood pressure demonstrate retention of sodium and water in the intravascular space as the vital mechanism for elevation of blood pressure. It is likely that some individuals can adjust their system to retention of solutes while others lack the capacity in one way or the other. Known risk factors including genetics, lifestyle or obesity all lead to the final step of salt and water retention by the kidneys. 

Therefore, it appears that the causes of primary hypertension are also linked to altered renal physiology— but not as apparent as in cases of secondary hypertension. More investigation into the pathophysiologic mechanisms of development of primary hypertension are necessary to clearly define the misprocessing of sodium and water by the kidneys in reaction to these risk elements and label that cause of primary hypertension also lie in the kidneys. To add to this theory, the majority of wondermolecules in the treatment of high blood pressure also act at the kidneys.

Whatever the background for high blood pressure, it appears that the primary mechanism for the genesis of essential hypertension lies in the kidneys and all risk factors initiate a cascade that ultimately reaches the kidneys before inducing a sustained elevation in blood pressure.

Bangladesh J Medicine 2026; Vol. 37, No. 2(1) pp. 184