Secondary Hypertension

Renal parenchymal disease (RPD): RPD is the most common cause of secondary hypertension accounting for 2.5% to 5% of all cases. The major features of this disorder include decreased ability of the kidneys to excrete excess fluid and salt, resulting in exacerbation of the hypertensive state.

Primary hyperaldosteronism: This disorder is characterized by overproduction of aldosterone, independent of the renin-angiotensin system, resulting in retention of excess salt and water, which in turn suppresses renin levels.

Renal vascular hypertension: This condition develops as a result of compromised arterial supply to the kidneys which is present in 1-2% of hypertensive patients.  Its cause may occur as a result of fibromuscular hyperplasia and atherosclerotic stenosis of the proximal renal arteries. It causes hypertension due to the excessive renin release resulting from reduction in renal blood flow and perfusion pressure.

Cushing’s syndrome: 80% of patients suffering from Cushing’s syndrome develop hypertension. The cause may be related to the mineralocorticoid effects of excess glucocorticoid, principally water and sodium retention. Cushings may be also develop as a result of increased levels of angiotensinogen that subsequently elevates the levels of angiotensin II.

Pheochromocytoma: Pheochromocytoma is an endocrine trigger for hypertension. This disorder is characterized by increased production of epinephrine and norepinephrine, thus increasing the level of catecholamines in blood, increasing sympathetic effects on cardiac cells and peripheral blood vessels, and increasing blood pressure and heart rate.

Drug contributors to hypertension: Many drugs can cause or worsen hypertension. Nonsteroidal anti-inflammatory drugs and COX-2 inhibitors can increase blood pressure due to their antiprostaglandin effect on the kidneys. Immunosuppressive drugs such as corticosteroids and cyclosporine increase blood pressure. High dosages of estrogens, which can be found in oral contraceptives, have a hypertensive effect. Furthermore, weight loss agents (sibutramine, phentermine), stimulants (nicotine, amphetamine), mineralocorticoids (fludrocortisone), antiparkinsonian (bromocriptine), monoamine oxidase inhibitors (phenelzine), anabolic steroids (testosterone), sympatomimetics (pseudoephedrine) molecules also raise the blood pressure.

Apnea: Obstructive sleep apnea, which is an obstruction of the upper airway during sleep, is a risk factor for hypertension. Hypertension occurs in more than 50% of patients with obstructive sleep apnea.