Pathology

How Kidney Disease Affects Cardiovascular Health



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The effects of chronic kidney disease (CKD) on the cardiovascular system (CVD) is a critical relationship, as people with severe CKD are the highest risk group for cardiovascular problems: angina, heart attack/failure, stroke. They are more likely to die of these diseases than develop kidney disease, and CVD is 10-30 times higher in dialysis patients than the general population.

The main function of the kidneys is to remove excess water and waste products from the blood and excrete them from the body through urination. These waste products come from food, breakdown of active tissue, and other substances such as drugs, supplements, additives, vitamins, etc. Filtration takes place in two sections of the kidneys: the glomeruli and the tubules.

On any given day, the kidneys filtrate approximately 45 gallons of fluid from the blood. The higher the concentration of substance in the blood, the greater the filtration rate, thus fluctuations in blood pressure. The entire blood volume gets filtered 20-25 times a day. While 2 quarts of fluid are excreted from the body as urine, the rest is recovered and kept to maintain fluid balance within the system. Urine can be stored in the bladder anywhere from 1-8 hours.

Besides fluid detoxification, the kidneys are also responsible for producing Vitamin D, a hormone-like vitamin that enables the absorption of calcium for bone health. Besides bone health, calcium is one of the main minerals needed to keep electrolyte balance in the body. An imbalance can lead to heart problems and stroke in individuals, as well as symptoms of numbness and fatigue. An electrolyte imbalance is frequently caused by a lack of water or fluids in the body, as well as mineral deficiencies such as calcium, magnesium, potassium, etc.; the kidneys play an important role in regulating and maintaining these levels in the body.

The kidneys also release several hormones: one stimulates red blood cell production (Erythropoietin), another regulates blood volume/pressure (Renin), and a third which controls the use of calcium throughout the body. Chronic kidney disease interferes with this third hormone, whereupon a person can develop calcified or stiffened arteries and heart valves. CKD also impedes the important function of renin, by holding in excess fluids (exacerbated by chronic dehydration), thus putting a strain on the heart. In turn, heart strain can lead to an enlarged left heart chamber (ventricular hypertrophy), resulting in heart failure.

For people with chronic kidney disease, disturbed hormonal levels tend to raise levels of LDL (bad cholesterol), becoming a risk factor for cardiovascular disease. People with either CKD or CVD are also prone to blood clots, as these clots (thrombosis) can lodge in blood vessels, cutting off blood supply, thereby creating risk of heart attack or stroke. A clot in one kidney artery can bring about high blood pressure.

Chronic kidney disease is a condition which develops gradually, therefore, can be divided into 5 stages of increasing severity. Mild kidney disease is called "renal insufficiency", while end-stage kidney disease is a near total or total loss of function. When kidney function is decreased, water, wastes, and toxins normally excreted by the kidneys are now accumulating in the bloodstream and various parts of the body. This dangerous accumulation can cause other problems like anemia, high blood pressure, acidosis (excessive acidity of body fluid), disorders of high cholesterol and fatty acids, bone disease.

Since diabetes is the main cause of kidney failure, early treatment of CKD can reduce cardiovascular disease and prevent further kidney damage. 20-30% of people with diabetes develop a kind of kidney disease called "diabetic nephropathy"; a person with this type of condition is 50 times more likely to develop CVD. (Permanent loss of kidney function may result in need for dialysis or kidney transplant to stay alive. Kidney function is measured by GFR, known as glomerular filtration rate.)

Because people with either CKD or CVD tend to have the same risk factors, it would behoove a person to make lifestyle changes: better diet, exercising, cessation of smoking and drinking, managing stress levels, plus taking medications for high blood pressure or high cholesterol when necessary, and, drinking lots of water.

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