Polycystic kidney disease
An inherited disorder, polycystic kidney disease is characterized by multiple, bilateral, grapelike clusters of fluid-filled cysts that grossly enlarge the kidneys, compressing and eventually replacing functioning renal tissue. This disease appears in two distinct forms.
The infantile form causes stillbirth or early neonatal death. A few infants with this disease survive for 2 years and then develop fatal renal, heart, or respiratory failure.
The adult form begins insidiously but usually becomes obvious between ages 30 and 50; rarely, it doesn’t cause symptoms until the patient is in his seventies. In the adult form, renal deterioration is more gradual but, as in the infantile form, progresses relentlessly to fatal uremia.
The prognosis in adults varies. Progression may be slow, even after symptoms of renal insufficiency appear. However, after uremic symptoms develop, polycystic kidney disease is usually fatal within 4 years, unless the patient receives treatment with dialysis, a kidney transplant, or both.
Causes
Although both types of polycystic kidney disease are genetically transmitted, the incidence in two distinct age-groups and different inheritance patterns suggest two unrelated disorders. The infantile type appears to be inherited as an autosomal recessive trait; the adult type, as an autosomal dominant trait. Both types affect males and females equally.
Signs and symptoms
Clinical features vary with the form of disease.
Infantile form
The neonate with infantile polycystic disease may have pronounced epicanthal folds, a pointed nose, a small chin, and floppy, low-set ears (Potter facies). Signs of respiratory distress and heart failure may be evident. Eventually, he develops uremia and renal failure. Accompanying hepatic fibrosis may cause the development of portal hypertension and bleeding varices.
Adult form
Adult polycystic kidney disease is commonly asymptomatic while the patient is in his thirties and forties but may induce nonspecific signs and symptoms, such as hypertension, polyuria, and urinary tract infection. Later, the patient develops overt signs and symptoms related to the enlarging kidney mass, such as lumbar pain, widening girth, and a swollen or tender abdomen. Such abdominal pain is usually worsened by exertion and relieved by lying down.
In advanced stages, this disease may cause recurrent hematuria, life-threatening retroperitoneal bleeding resulting from a ruptured cyst, proteinuria, and colicky abdominal pain from the ureteral passage of clots or calculi. Generally, about 10 years after symptoms appear, progressive compression of kidney structures by the enlarging mass produces renal failure and uremia.
Diagnosis
A family history and a physical examination revealing large bilateral, irregular masses in the flanks strongly suggest polycystic kidney disease. In advanced stages, grossly enlarged and palpable kidneys make the diagnosis obvious. (See Visualizing the polycystic kidney.) In patients with these findings, the following laboratory results are typical:
❑ Excretory urography or retrograde ureteropyelography reveals enlarged kidneys, with elongation of the renal pelvis, flattening of the calyces, and indentations caused by cysts. Excretory urography of the neonate shows poor excretion of contrast medium.
❑ Ultrasonography, tomography, and radioisotope scans show kidney enlargement and cysts. Computed tomography scan and magnetic resonance imaging show multiple areas of cystic damage.
❑ Urinalysis and creatinine clearance tests (nonspecific tests that evaluate renal function) indicate abnormalities.
CLINICAL TIP: Diagnosis must rule out the presence of renal tumors.
Treatment
Polycystic kidney disease can’t be cured. The primary goal of treatment is to preserve renal parenchyma and prevent infectious complications. Management of secondary hypertension will also help prevent rapid deterioration in function. Progressive renal failure requires treatment similar to that for other types of renal disease, including dialysis or, rarely, a kidney transplant.
Asymptomatic stage
When adult polycystic kidney disease is discovered in the asymptomatic stage, careful monitoring is required, including urine cultures and creatinine clearance tests every 6 months. When a urine culture detects infection, prompt and vigorous antibiotic treatment is needed (even when the patient is asymptomatic).
Progressive renal impairment
As renal impairment progresses, selected patients may undergo dialysis, transplantation, or both. Cystic abscess or retroperitoneal bleeding may require surgical drainage; intractable pain (a rare symptom) may also require surgery. Anemia is treated with iron and other supplements, erythropoietin, or blood transfusions. However, because this disease affects both kidneys, nephrectomy usually isn’t recommended because it increases the risk of infection in the remaining kidney.
Special considerations
❑ Because polycystic kidney disease is usually relentlessly progressive, comprehensive patient teaching and emotional support are essential.
❑ Refer the young adult patient or the parents of an infant with polycystic kidney disease for genetic counseling. Such parents will probably have many questions about the risk to other offspring.
❑ Provide supportive care to minimize associated symptoms. Carefully assess the patient’s lifestyle and his physical and mental status, and determine how rapidly the disease is progressing. Use this information to individualize the patient’s care plan.
❑ Acquaint yourself with all aspects of end-stage renal disease, including dialysis and transplantation, so that you can provide appropriate care and patient teaching as the disease progresses.
❑ Explain all diagnostic procedures to the patient or to his family if the patient is an infant. Before beginning excretory urography or other procedures that use an iodine-based contrast medium, determine whether the patient has ever had an allergic reaction to iodine or shellfish. Even if the patient doesn’t have a history of allergy, watch for an allergic reaction after performing the procedures.
❑ Administer antibiotics for urinary tract infection. Stress to the patient the need to take the medication exactly as prescribed, even if symptoms are minimal or absent.
Pictures
Book Source Details
- Book Title: Handbook of Diseases
- Author(s): Springhouse
- Year of Publication: 2003
- Copyright Details: Handbook of Diseases, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Handbook of Diseases
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2003
ISBN: 1-58255-266-5
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