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START READING AGAIN: The main effect of the baroreceptor reflex is to reduce moment-by-moment changes in BP. The reflex is not involved in long term BP control and cannot prevent chronic HTN, because it resets to a baseline pressure in order to consistently prevent momentary changes.
Relatively uncommon, but important to look at because of the potential to cure. Also if we wait too long to treat a cause of secondary HTN, the changes incurred may become permanent.
Clues for suspecting a secondary HTN:
AGE: if hypertension develops before age 20 or after age 50
SEVERITY: more severe hypertension (Stage 3)
ONSET: abrupt onset in previously normotensive patient
SIGNS of the cause: ex = bruit from renal artery stenosis
FAMILY HISTORY: negative, usually occurs sporadically
Causes of Secondary HTN
renal causes (renal parenchymal disease and renal artery stenosis)
mechanical causes (coarctation of the aorta)
endocrine causes (pheochromocytoma, adrenocortical hormone excess,
thyroid hormone excess)
~ The objectives suggest that we need to know signs, symptoms and lab findings for the 4 causes of secondary hypertension. Here we go. ~
Exogenous Causes: Medications
oral contraceptives. Estrogens can increase hepatic synthesis of angiotensinogen, which leads to more ang II. More ang II causes vasoconstriction and increased aldosterone release, which will increase sodium retention = ↑ volume.
Erythropoietin (increased blood viscosity)
Sympathomimetic drugs (cold medicine)
Chronic alcohol consumption
Renal Causes: two types
renal parenchymal disease
Increased intravascular volume causes damage to the kidney.
Damaged nephrons are unable to excrete normal amounts of water and Na, thereby increasing the volume further
Can also involve secretion of lots of renin