The Kidneys And How They Work?

Why do kidneys fail?

Most kidney diseases attack the nephrons, causing them to lose their filtering capacity. Damage to the nephrons can happen quickly, often as the result of injury or poisoning. But most kidney diseases destroy the nephrons slowly and silently. Only after years or even decades will the damage become apparent. Most kidney diseases attack both kidneys simultaneously.

The two most common causes of kidney disease are diabetes and high blood pressure. People with a family history of any kind of kidney problem are also at risk for kidney disease.

Diabetes and high blood pressure are the most common causes of chronic kidney disease (CKD).

  1. Diabetic Kidney Disease: Diabetes, both type 1 and type 2 diabetes, can damage the kidneys, with a loss of kidney function that’s often progressive over time. Medical care can slow, but not reverse, this kidney damage. Diabetes is a leading reason why people need dialysis or a kidney transplant. Keeping blood glucose levels down can delay or prevent diabetic kidney disease. Use of medications called angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) to treat high blood pressure can also slow or delay the progression of diabetic kidney disease.
  2. High Blood Pressure: High blood pressure (hypertension) contributes to a loss of kidney function, generally over years. Hypertension can damage the small blood vessels in the kidneys and accelerate kidney damage from other diseases such as diabetes, as well. The damaged vessels cannot filter wastes from the blood as they are supposed to. A doctor may prescribe blood pressure medication. ACE inhibitors and ARBs have been found to protect the kidneys even more than other medicines that lower blood pressure to similar levels. The National Heart, Lung, and Blood Institute (NHLBI), one of the National Institutes of Health, recommends that people with diabetes or reduced kidney function keep their blood pressure below 130/80.
  3. Glomerular Diseases: Several types of kidney disease are grouped together under this category, including autoimmune diseases, infection-related diseases, and sclerotic diseases. As the name indicates, glomerular diseases attack the tiny blood vessels, or glomeruli, within the kidney. This can happen suddenly or can lead to chronic disease and can cause progressive kidney damage and loss of function. The most common primary glomerular diseases include membranous nephropathy, IgA nephropathy, and focal segmental glomerulosclerosis. The first sign of a glomerular disease is often proteinuria, which is too much protein in the urine. Another common sign is hematuria, which is blood in the urine. Some people may have both proteinuria and hematuria. Glomerular diseases can slowly destroy kidney function. Blood pressure control is important with any kidney disease. Glomerular diseases are usually diagnosed with a biopsy—a procedure that involves taking a piece of kidney tissue for examination with a microscope. Treatments for glomerular diseases may include immunosuppressive drugs or steroids to reduce inflammation and proteinuria, depending on the specific disease.
  4. Obstruction in urine flow due to renal stones or prostate problem can damage the kidneys if the problem is not solved on time.
  5. Immune system conditions, such as lupus, and chronic viral illnesses such as HIV/AIDS, hepatitis B, and hepatitis C can cause kidney damage.
  6. A severe infection within the kidneys themselves, called pyelonephritis, can lead to scarring as the infection heals. Multiple episodes can lead to kidney damage.
  7. Polycystic kidney disease: Some kidney diseases result from hereditary factors. Polycystic kidney disease (PKD) is the most common form of inherited kidney disease. With this condition, fluid-filled cysts form in the kidneys over time, which can slowly replace much of the mass of the kidneys, reducing kidney function and leading to kidney failure. The symptoms of high blood pressure and renal failure usually do not occur until patients are in their twenties or thirties
  8. Congenital defects, which are present at birth, are often the result of a urinary tract obstruction or malformation that affects the kidneys. One of the most common involves a valve-like mechanism between the bladder and urethra. These defects, sometimes found while a baby is still in the womb, can often be surgically repaired by a urologist. The signs of kidney disease in children vary. A child may grow unusually slowly, vomit often, or have back or side pain. Some kidney diseases may be silent—causing no signs or symptoms—for months or even years. If a child has a kidney disease, the child’s doctor should find it during a regular checkup. The first sign of a kidney problem may be high blood pressure; a low number of red blood cells, called anemia; proteinuria; or hematuria. If the doctor finds any of these problems, further tests may be necessary, including additional blood and urine tests or radiology studies. In some cases, the doctor may need to perform a biopsy.
  9. Drugs and toxins, including long-term exposure to some medications and chemicals, can damage the kidneys. Overuse of pain killers (nonsteroidal anti-inflammatory drugs) such as ibuprofen, diclofenac and paracetamol can be harmful to the kidneys in some people. Intravenous “street” drugs can cause kidney disease.

How do kidneys fail?

Many factors that influence the speed of kidney failure are not completely understood. Researchers are still studying how protein in the diet and cholesterol levels in the blood affect kidney function.

Acute Kidney Injury

The loss of kidney function over several hours or days is called acute kidney injury, also known as acute renal failure (ARF). This can occur due to dehydration from excessive diarrhea or vomiting, or working in hot weather without drinking adequate fluids. Other causes can be long lasting fever leading to sepsis, obstruction of the urine flow due to stones or prostate problem, damage from certain drugs or toxins (eg. Some antibiotics, pain killers, or wasp toxins).

AKI may lead to permanent loss of kidney function. But if the kidneys are not seriously damaged, acute kidney disease may be reversed.

Chronic Kidney Disease

Kidney damage and decreased function lasting longer than 3 months is called chronic kidney disease (CKD). Chronic kidney disease is particularly dangerous since you may not have any symptoms until considerable, often irreparable, kidney damage has been done. People with CKD may go on to develop permanent kidney failure. They also have a high risk of death from a stroke or heart attack.

End-stage Renal Disease

Total or nearly total and permanent kidney failure is called end-stage renal disease (ESRD). People with ESRD must undergo dialysis or transplantation to stay alive.

What are the signs of chronic kidney disease (CKD)?

People in the early stages of CKD usually do not feel sick at all.

People whose kidney disease has gotten worse may

  • need to urinate more often or less often
  • feel tired
  • lose their appetite or experience nausea and vomiting
  • have swelling in their hands or feet
  • feel itchy or numb
  • get drowsy or have trouble concentrating
  • have darkened skin
  • have muscle cramps

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