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.
Diabetic Kidney Disease
Diabetes is a disease that keeps the body from using glucose, a form of sugar, as it should. If glucose stays in the blood instead of breaking down, it can act like a poison. Damage to the nephrons from unused glucose in the blood is called diabetic kidney disease. Keeping blood glucose levels down can delay or prevent diabetic kidney disease.
High Blood Pressure
High blood pressure can damage the small blood vessels in the kidneys. 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.
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. 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. 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.
Inherited and Congenital Kidney Diseases
Some kidney diseases result from hereditary factors. Polycystic kidney disease (PKD), for example, is a genetic disorder in which many cysts grow in the kidneys. PKD cysts can slowly replace much of the mass of the kidneys, reducing kidney function and leading to kidney failure. Some kidney problems may show up when a child is still developing in the womb. Examples include autosomal recessive PKD, a rare form of PKD, and other developmental problems that interfere with the normal formation of the nephrons. 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.
Some hereditary kidney diseases may not be detected until adulthood. The most common form of PKD was once called "adult PKD" because the symptoms of high blood pressure and renal failure usually do not occur until patients are in their twenties or thirties. But with advances in diagnostic imaging technology, doctors have found cysts in children and adolescents before any symptoms appear.
Other Causes of Kidney Disease
Poisons and trauma, such as a direct and forceful blow to the kidneys, can lead to kidney disease. Some over-the-counter medicines can be poisonous to the kidneys if taken regularly over a long period of time. Anyone who takes painkillers regularly should check with a doctor to make sure the kidneys are not at risk.