Polycystic Kidney Disease.Polycystic kidney disease Polycystic Kidney Disease Definition Polycystic kidney disease (PKD) is one of the most common of all life-threatening human genetic disorders. (PKD Noun 1. PKD - kidney disease characterized by enlarged kidneys containing many cysts; often leads to kidney failure polycystic kidney disease kidney disease, nephropathy, renal disorder, nephrosis - a disease affecting the kidneys ) is a genetic disorder characterized by the growth of numerous cysts in the kidneys. The cysts are filled with fluid. PKD cysts can slowly replace much of the mass of the kidneys, reducing kidney function and leading to kidney failure kidney failure or renal failure Partial or complete loss of kidney function. Acute failure causes reduced urine output and blood chemical imbalance, including uremia. Most patients recover within six weeks. . 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 from the blood to form urine. They also regulate amounts of certain vital substances in the body. When PKD causes kidneys to fail--which usually happens only after many years--the patient requires dialysis or kidney transplantation Kidney Transplantation Definition Kidney transplantation is a surgical procedure to remove a healthy, functioning kidney from a living or brain-dead donor and implant it into a patient with non-functioning kidneys. . About one-half of people with the major type of PKD progress to kidney failure, i.e., end-stage renal disease End-stage renal disease (ESRD) Total kidney failure; chronic kidney failure is diagnosed as ESRD when kidney function falls to 5-10% of capacity. Mentioned in: Chronic Kidney Failure end-stage renal disease (ESRD ESRD end-stage renal disease. ESRD End-stage renal disease; chronic or permanent kidney failure. Mentioned in: Dialysis, Kidney ESRD End-stage renal disease, see there ). PKD can cause cysts in the liver and problems in other organs, such as the heart and blood vessels Blood vessels Tubular channels for blood transport, of which there are three principal types: arteries, capillaries, and veins. Only the larger arteries and veins in the body bear distinct names. in the brain. These complications 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 500,000 people have PKD, and it is the fourth leading cause of kidney failure. Medical professionals describe two major inherited forms of PKD and a noninherited form: * Autosomal dominant Autosomal dominant A pattern of inheritance in which only one of the two copies of an autosomal gene must be abnormal for a genetic condition or disease to occur. An autosomal gene is a gene that is located on one of the autosomes or non-sex chromosomes. 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 Autosomal recessive A pattern of inheritance in which both copies of an autosomal gene must be abnormal for a genetic condition or disease to occur. An autosomal gene is a gene that is located on one of the autosomes or non-sex chromosomes. PKD is a rare, inherited form. Symptoms of autosomal recessive PKD begin in the earliest months of life, even in the womb. * Acquired cystic kidney disease Kidney Disease Definition Kidney disease is a general term for any damage that reduces the functioning of the kidney. Kidney disease is also called renal disease. (ACKD ACKD Acquired Cystic Kidney Disease ) develops in association with long-term kidney problems, especially in patients who have kidney failure and who have been on dialysis for a long time. Therefore it tends to occur in later years of life. It is not an inherited form of PKD. Autosomal Dominant PKD What Is Autosomal Dominant PKD? Autosomal dominant PKD is one of the most common inherited disorders. The phrase "autosomal dominant" means that if one parent has the disease, there is a 50-percent chance that the disease will pass to a child (see Genetic Diseases). At least one parent must have the disease for a child to inherit it. Either the mother or father can pass it along, but new mutations may account for one-fourth of new cases. In some rare cases, the cause of autosomal dominant PKD occurs spontaneously in the child soon after conception--in these cases the parents are not the source of this disease. Many people with autosomal dominant PKD live for 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, even in the first years of life. The disease is thought to occur equally in men and women and equally in people of all races. However, some studies suggest that it occurs more often in whites than in blacks and more often in females than in males. High blood pressure occurs early in the disease, often before cysts appear. 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 retaining roughly their kidney shape. In fully developed PKD, a cyst-filled kidney can weigh as much as 22 pounds. 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 dull pain can be temporary or persistent, mild or severe. People with autosomal dominant PKD also can experience the following: * Urinary tract infections * Hematuria hematuria Blood in the urine. It usually indicates injury or disease of the kidney or another structure of the urinary system or possibly, in males, the reproductive system. It may result from infection, inflammation, tumours, kidney stones, or other disorders. (blood in the urine) * Liver and pancreatic cysts * Abnormal heart valves Heart valves Valves that regulate blood flow into and out of the heart chambers. Mentioned in: Heart Failure * High blood pressure * Kidney stones Kidney Stones Definition Kidney stones are solid accumulations of material that form in the tubal system of the kidney. Kidney stones cause problems when they block the flow of urine through or out of the kidney. * Aneurysms (bulges in the walls of blood vessels) in the brain * Diverticulosis diverticulosis, a disorder characterized by the presence of diverticula, which are small, usually multiple saclike protrusions through the wall of the colon (large intestine). (small sacs on the colon). How Is Autosomal Dominant PKD Diagnosed? To diagnose autosomal dominant PKD, a doctor typically observes three or more kidney cysts using ultrasound imaging. The diagnosis is strengthened by a family history of autosomal dominant PKD and the presence of cysts in other organs. In most cases of autosomal dominant PKD, the person's physical condition appears normal for many years, even decades, so the disease can go unnoticed. Physical checkups and blood and urine tests may not lead to diagnosis. The slow, undetected progression is why some people live for many years without knowing they have autosomal dominant PKD. Once cysts have formed, however, diagnosis is possible with imaging technology. Ultrasound, which passes sound waves through the body to create a picture of the kidneys, is used most often. Ultrasound imaging employs no injected dyes or radiation and is safe for all patients including pregnant women. It can also detect cysts in the kidneys of a fetus. More powerful and expensive imaging methods such as computed tomography Computed tomography (CT scan) X rays are aimed at slices of the body (by rotating equipment) and results are assembled with a computer to give a three-dimensional picture of a structure. (CT scan CT scan: see CAT scan. See CAT scan. ) and magnetic resonance imaging magnetic resonance imaging (MRI), noninvasive diagnostic technique that uses nuclear magnetic resonance to produce cross-sectional images of organs and other internal body structures. (MRI 1. (application) MRI - Magnetic Resonance Imaging. 2. MRI - Measurement Requirements and Interface. ) also can detect cysts, but these methods usually are not required because ultrasound provides adequate information. CT scans require x-rays and sometimes injected dyes. In the future, DNA testing DNA testing Analysis of DNA (the genetic component of cells) in order to determine changes in genes that may indicate a specific disorder. Mentioned in: Acoustic Neuroma, Retinoblastoma, Von Willebrand Disease will be able to confirm a diagnosis of autosomal dominant PKD before cysts develop. (See The Search for PKD Genes) How Is Autosomal Dominant PKD Treated? Although a cure for autosomal dominant PKD is not available, treatment can ease the symptoms and prolong life. Pain. A doctor will first suggest over-the-counter pain medications, such as aspirin or Tylenol. For most but not all cases of severe pain, surgery to shrink cysts can relieve pain in the back and flanks. However, surgery provides only temporary relief and does not slow the disease's progression, in many cases, toward kidney failure. Headaches that are severe or that seem to feel different from other headaches might be caused by aneurysms, or swollen blood vessels, in the brain. Headaches also can be caused by high blood pressure. People with autosomal dominant PKD should see a doctor if they have severe or recurring headaches-even before considering over-the-counter pain medications. Urinary Tract Infections. Patients with autosomal dominant PKD tend to have frequent urinary tract infections, which can be treated with antibiotics. People with the disease should seek treatment for urinary tract infections immediately, because infection can spread from the urinary tract to the cysts in the kidneys. Cyst cyst, abnormal sac in the body, filled with a fluid or semisolid and enclosed in a membrane. Cysts can be congenital but are usually acquired, the most common locations being the skin and the ovaries. infections are difficult to treat because many antibiotics do not penetrate into the cysts. However, some antibiotics are effective. High Blood Pressure. Keeping blood pressure under control can slow the effects of autosomal dominant PKD. Lifestyle changes and various medications can lower high blood pressure. Patients should ask their doctors about such treatments. Sometimes proper diet and exercise are enough to keep blood pressure low. End-Stage Renal Disease. Because kidneys are essential for life, people with ESRD must seek one of two options for replacing kidney functions: dialysis or transplantation. In hemodialysis, blood is circulated into an external machine, where it is cleaned before reentering re·en·ter also re-en·ter v. re·en·tered, re·en·ter·ing, re·en·ters v.tr. 1. To enter or come in to again. 2. To record again on a list or ledger. v.intr. the body; in peritoneal dialysis peritoneal dialysis n. The removal of soluble substances and water from the body by transfer across the peritoneum, utilizing a solution which is intermittently introduced into and removed from the peritoneal cavity. , a fluid is introduced into the abdomen, where it absorbs wastes, and it is then removed. Transplantation of healthy kidneys into ESRD patients has become a common and successful procedure. Healthy (non-PKD) kidneys transplanted into PKD patients do not develop cysts. Autosomal Recessive PKD What Is Autosomal Recessive PKD? Autosomal recessive PKD is caused by a particular genetic flaw that is different from the genetic flaw that causes autosomal dominant PKD. Parents who do not have the disease can have a child with the disease if both parents carry the abnormal gene and both pass the gene to their baby. The chance of this happening (when both parents carry the abnormal gene) is one in four. If only one parent carries the abnormal gene, the baby cannot get the disease. The symptoms of autosomal recessive PKD can begin before birth, so it is often called "infantile PKD." Children born with autosomal recessive PKD usually develop kidney failure within a few years. Severity of the disease varies. Babies with the worst cases die hours or days after birth. Children with an infantile version may have sufficient renal function for normal activities for a few years. People with the juvenile version may live into their teens and twenties and usually will have liver problems as well. What Are the Symptoms of Autosomal Recessive PKD? Children with autosomal recessive PKD experience high blood pressure, urinary tract infections, and frequent urination urination Process of excreting urine from the bladder (see urinary system). Nerve centres in the spinal cord, brain stem, and cerebral cortex control it through involuntary and voluntary muscles. The need to void is felt when the bladder holds 3. . The disease usually affects the liver, spleen, and pancreas, resulting in low blood-cell counts, varicose veins Varicose Veins Definition Varicose veins are dilated, tortuous, elongated superficial veins that are usually seen in the legs. Description , and hemorrhoids hemorrhoids (hĕm`əroidz) or piles, dilatations of the veins about the anus (external hemorrhoids) or those higher up inside it (internal hemorrhoids). . Because kidney function is crucial for early physical development, children with autosomal recessive PKD are usually smaller than average size. How Is Autosomal Recessive PKD Diagnosed? Ultrasound imaging of the fetus or newborn baby reveals cysts in the kidneys but does not distinguish between the cysts of auto-somal recessive recessive /re·ces·sive/ (re-ses´iv) 1. tending to recede; in genetics, incapable of expression unless the responsible allele is carried by both members of a pair of homologous chromosomes. 2. and autosomal dominant PKD. Ultrasound examination Ultrasound examination A medical test in which high frequency sound waves are directed at a particular internal area of the body. As the sound waves are reflected by internal structures, a computer uses the data to construct an image of the structures. of kidneys of relatives can be helpful; for example, a parent or grandparent with autosomal dominant PKD cysts could help confirm diagnosis of autosomal dominant PKD in a fetus or child. (It is extremely rare, although not impossible, for a person with autosomal recessive PKD to become a parent.) Because autosomal recessive PKD tends to scar the liver, ultrasound imaging of the liver also aids in diagnosis. How Is Autosomal Recessive PKD Treated? Medicines can control high blood pressure in autosomal recessive PKD, and antibiotics can control urinary tract infections. Eating increased amounts of nutritious food improves growth in children with autosomal recessive PKD. In some cases, growth hormones are used. In response to kidney failure, autosomal recessive PKD patients must receive dialysis or transplantation. (See End-Stage Renal Disease) Genetic Diseases Genes are segments of DNA DNA: see nucleic acid. DNA or deoxyribonucleic acid One of two types of nucleic acid (the other is RNA); a complex organic compound found in all living cells and many viruses. It is the chemical substance of genes. , the long molecules that reside in the nuclei of your body's cells. The genes, through complex processes, cause chemical activities that lead to growth and maintenance of the body. At conception, DNA (and therefore genes) from both parents are passed to the child. A genetic disease occurs when one or both parents pass abnormal genes to a child at conception. If receiving an abnormal gene from just one parent is enough to produce a disease in the child, the disease is said to have dominant inheritance dominant inheritance n. Inheritance in which an allele produces the same phenotypic effect whether inherited with a homozygous or heterozygous allele. . If receiving abnormal genes from both parents is needed to produce disease in the child, the disease is said to be recessive. The chance of acquiring a dominant disease (one gene copy is enough) is higher than the chance of acquiring a recessive disease (two gene copies are needed). A child who receives only one gene copy for a recessive disease at conception will not develop the genetic disease (such as autosomal recessive PKD), but could pass the gene to the following generation. Acquired Cystic Kidney Disease What Is ACKD? ACKD develops in kidneys with long-term damage and bad scarring, so it often is associated with dialysis and end-stage renal disease. About 90 percent of people on dialysis for 5 years develop ACKD. People with ACKD can have any underlying kidney disease, such as glomerulonephritis glomerulonephritis: see nephritis. or kidney disease of diabetes. The cysts of ACKD may bleed. Kidney tumors, including kidney (renal) cancer, can develop in people with ACKD. Renal cancer is rare yet occurs at least twice as often in ACKD patients as in the general population. How Is ACKD Diagnosed? Patients with ACKD usually seek help because they notice blood in their urine (hematuria). The cysts bleed into the urinary system, which discolors urine. Diagnosis is confirmed using ultrasound, CT scan, or MRI of the kidneys. How Is ACKD Treated? Most ACKD patients are already receiving treatment for kidney problems. In rare cases, surgery is used to stop bleeding of cysts and to remove tumors or suspected tumors. The Search for PKD Genes Scientists have not determined the processes that trigger formation of PKD cysts. However, in recent years progress has been made in understanding the abnormal genes responsible for autosomal dominant and autosomal recessive PKD. Scientists have not yet developed clinical tests that determine whether a person carries a PKD gene. In 1985, scientists narrowed their hunt for a PKD gene to a particular portion of human chromosome 16. In 1994, they precisely identified a gene associated with the vast majority of cases of autosomal dominant PKD. They named the gene "PKD 1," knowing that one or more additional genes for autosomal dominant PKD have yet to be found. By 1995, scientists had produced a map of the PKD1 gene, showing all of its molecular components. Scientists have continued to search for the autosomal recessive PKD gene. By 1995, they knew that a gene responsible for at least some cases of autosomal recessive PKD resides on chromosome 6. Scientists will study PKD genes to learn their effects on chemical processes in the body. Knowing the effects will lead to better treatments for the diseases. Eventually, scientists may be able to correct genetic defects, eliminating the diseases entirely. Points to Remember The three types of PKD are: * Two inherited forms: * A common form usually causes symptoms in midlife mid·life n. See middle age. adj. Of, relating to, or characteristic of middle age. . * A rare form usually causes symptoms in early childhood. * A noninherited form is associated with long-term kidney problems, dialysis, and old age. The signs of PKD include: * Pain in the back and lower sides * Headaches * Urinary tract infections * Blood in the urine * Cysts in the kidneys and other organs. Diagnosis of PKD is obtained by: * Ultrasound imaging of kidney cysts * Ultrasound imaging of cysts in other organs * Family medical history. PKD has no cure. Treatments include: * Medicine and surgery to reduce pain * Antibiotics to resolve infections * Dialysis and transplantation to replace functions of failed kidneys. Additional Resources Polycystic Kidney Research Foundation 4901 Main Street Suite 320 Kansas City, MO 64112 (800) 753-2873 American Association of Kidney Patients 100 South Ashley Drive Suite 280 Tampa, FL 33602 (800) 749-2257 National Kidney Foundation 30 East 33rd Street New York, NY 10016 (800) 622-9010 The U.S. Government does not endorse or favor any specific commercial product or company. Trade, proprietary, or company names appearing in this publication are used only because they are considered essential in the context of the information reported herein. National Kidney and Urologic Diseases Information Clearinghouse 3 Information Way Bethesda, MD 20892-3580 E-mail:nkudic@info.niddk.nih.gov The National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC NKUDIC National Kidney and Urologic Diseases Information Clearinghouse ) is a service of the National Institute of Diabetes and Digestive and Kidney Diseases About NIDDK The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), of the U.S. National Institutes of Health, conducts and supports research on many of the most serious diseases affecting public health. (NIDDK NIDDK National Institute of Diabetes and Digestive and Kidney Diseases ). The NIDDK is part of the National Institutes of Health under the U.S. Public Health Service. Established in 1987, the clearinghouse provides information about diseases of the kidneys and urologic system to people with kidney and urologic disorders and to their families, health care professionals, and the public. NKUDIC answers inquiries; develops, reviews, and distributes publications; and works closely with professional and patient organizations and Government agencies to coordinate resources about kidney and urologic diseases. Publications produced by the clearinghouse are carefully reviewed for scientific accuracy, content, and readability. This e-text is not copyrighted. The clearinghouse encourages users of this e-pub to duplicate and distribute as many copies as desired. NIH "Not invented here." See digispeak. NIH - The United States National Institutes of Health. Publication No. 96-4008 April 1996 e-text posted: 12 February 1998 |
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