Kidney disease often entails high blood pressure, and conversely, high blood pressure damages the kidney in the long term, leading to renal insufficiency: 20% of all hypertensive patients die from kidney disease alone. Kidney damage is thus the third leading cause of death in people with hypertension. Kidney disease and hypertension are mutually dependent and often exacerbate each other. Routine blood pressure measurements are therefore active kidney protection – for kidney patients, lowering high pressure is an important measure to delay the progression of the disease.
How are kidney and blood pressure related?
You might be surprised to learn that the kidney also regulates blood pressure. However, it is not only an organ of detoxification and production of hormones, it also regulates the “levels” of the body for salts, for water and for the level of blood pressure.
Almost all diseases of the kidneys are accompanied by increased blood pressure. The reason for this may be an impaired ability of the kidneys to control fluid balance, which manifests itself in decreased urine output. The connection between blood pressure and urine excretion has been proven – for example, certain antihypertensive drugs (diuretics) have an indirect blood pressure-lowering effect simply because of their diuretic properties.
High-impact: causes are mutually dependent
Vascular changes in the kidneys are often the cause of hypertension. Conversely, however, vascular changes in the kidneys can also be the consequences of hypertension. Of great importance for the progression of the loss of kidney function is the extent of proteinuria (protein loss via urine), but also the dimension of the high pressure from which a large number of kidney patients suffer. Effective blood pressure reduction is therefore a crucial prerequisite for slowing the disease process and can prolong dialysis-free life.
Therapy
If advanced renal insufficiency is already present, blood pressure should be lowered to at least optimal levels (130/80 mm Hg). The latest guidelines of the German Hypertension League even suggest values <125/75 mmHg.
Many studies have demonstrated that inhibitors of the renin-angiotensin system (primarily ACE inhibitors, but also angiotensin receptor blockers) exert a specific protective effect on renal function that goes beyond blood pressure reduction. They are therefore considered basic therapy and should also be used in high doses or in combination in difficult situations.
Fatal interaction
The treatment of hypertension is not simple and, fatally, is still often neglected in patients with renal insufficiency. Referral to a specialist, the nephrologist, is often too late and often the prescription of effective, but also more expensive, medications is bypassed – possibly for “budgetary reasons.”
The Society of Nephrology would like to raise awareness among primary care physicians, as well as the general public, about this momentous interaction between high blood pressure and the kidney: Hypertensive patients are potential kidney patients and form a “risk group” for kidney failure. Kidney patients are (almost always) hypertensive patients – with the consequence (=high pressure) amplifying the cause (=kidney disease). To slow down the disease process, it is essential to get the high pressure under control.