Polycystic Kidney Disease

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Polycystic kidney disease (PKD) is a genetic disorder characterized by the growth of numerous cysts in the kidneys. The kidneys are two organs, each about the size of a fist, located in the upper part of a person's abdomen, toward the back. The kidneys filter wastes and extra fluid from the blood to form urine. They also regulate amounts of certain vital substances in the body. When cysts form in the kidneys, they are filled with fluid. PKD cysts can profoundly enlarge the kidneys while replacing much of the normal structure, resulting in reduced kidney function and leading to kidney failure. When PKD causes kidneys to fail-which usually happens after many years-the patient requires dialysis or kidney transplantation. About one-half of people with the most common type of PKD progress to kidney failure, also called end-stage renal disease (ESRD). PKD can also cause cysts in the liver and problems in other organs, such as blood vessels in the brain and heart. The number of cysts as well as the complications they cause help doctors distinguish PKD from the usually harmless "simple" cysts that often form in the kidneys in later years of life. In the United States, about 600,000 people have PKD, and cystic disease is the fourth leading cause of kidney failure. Two major inherited forms of PKD exist: Autosomal dominant PKD is the most common inherited form. Symptoms usually develop between the ages of 30 and 40, but they can begin earlier, even in childhood. About 90 percent of all PKD cases are autosomal dominant PKD.

Autosomal recessive PKD is a rare inherited form. Symptoms of autosomal recessive PKD begin in the earliest months of life, even in the womb Autosomal dominant PKD is the most common inherited disorder of the kidneys. The phrase “autosomal dominant” means that if one parent has the disease, there is a 50 percent chance that the disease gene will pass to a child. In some cases—perhaps 10 percent—autosomal dominant PKD occurs spontaneously in patients. In these cases, neither of the parents carries a copy of the disease gene. Many people with autosomal dominant PKD live for several decades without developing symptoms. For this reason, autosomal dominant PKD is often called “adult polycystic kidney disease.” Yet, in some cases, cysts may form earlier in life and grow quickly, causing symptoms in childhood The cysts grow out of nephrons, the tiny filtering units inside the kidneys. The cysts eventually separate from the nephrons and continue to enlarge. The kidneys enlarge along with the cysts—which can number in the thousands—while roughly retaining their kidney shape. In fully developed autosomal dominant PKD, a cyst-filled kidney can weigh as much as 20 to 30 pounds. High blood pressure is common and develops in most patients by age 20 or 30. What are the symptoms of autosomal dominant PKD?

The most common symptoms are pain in the back and the sides—between the ribs and hips—and headaches. The pain can be temporary or persistent, mild or severe. People with autosomal dominant PKD also can experience the following complications: urinary tract infections—specifically, in the kidney cysts hematuria—blood in the urine

liver and pancreatic cysts
abnormal heart valves
high blood pressure
kidney stones
aneurysms—bulges in the walls of blood vessels—in the brain diverticulosis—small pouches bulge outward through the colon How is autosomal dominant PKD diagnosed?
Autosomal dominant PKD is usually diagnosed by kidney imaging studies. The most common form of diagnostic kidney imaging is ultrasound, but more precise studies, such as computerized tomography (CT) scans or magnetic resonance imaging (MRI) are also widely used. In autosomal dominant PKD, the onset of kidney damage and how quickly the disease progresses can vary. Kidney imaging findings can also vary considerably, depending on a patient’s age. Younger patients usually have both fewer and smaller cysts. Doctors have therefore developed specific...
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