550 UNIT VIII RENAL AND UROLOGICAL DISORDERS
African Americans. Most commonly, young adults from age 20 to 30 years, as well as older adults aged 60 to 70 years, develop the disease. Among young adults, men are more likely to develop the disease. Among older adults, women are predominately affected com- pared with men. Between 60% and 80% of patients have clinically apparent manifestations of pulmo- nary and renal disease, 20% to 40% have renal disease alone, and fewer than 10% have disease that is limited to the lungs. Etiology Goodpasture’s syndrome is an autoimmune disease of unknown etiology. Autoantibodies develop against the collagen in renal glomerular membranes and pul- monary alveolar membranes. There is a strong genetic predisposition in Goodpasture’s syndrome, and per- sons with the specific tissue type HLA-DR15 are more susceptible than others. Pulmonary involvement is influenced by factors that increase the permeability of the alveolar–capillary membrane such as smoking, infection, or exposure to solvents. Pathophysiology In Goodpasture’s syndrome, autoantibodies develop against a specific type of collagen within the glomeru- lar and alveolar membranes and initiate an inflamma- tory process. Direct immunofluorescence techniques demonstrate linear deposition of immunoglobulins in the glomerular and alveolar membranes. Persons with tissue type HLA-DR15, HLA DRB1*1501, and HLA-B7 are at high risk for the disorder in the kidney and lungs. T cells play a key role in the initiation of the dis- order. T cells assist B cells to secrete immunoglobulins that attack kidney and lung membranes. Glomerular inflammation causes decreased nephron function. The ability of the kidneys to filter blood and excrete urine is impaired. Autoantibody attacks on alveolar mem- branes cause diminished gas exchange and inflamma- tory changes in the lungs. Clinical Presentation The patient with Goodpasture’s syndrome presents with nonspecific symptoms of malaise, chills, and fever. Renal manifestations include hematuria, edema, high blood pressure, and eventually renal failure. Along with pulmonary involvement, dyspnea, pleuritic chest pain, cough, and hemoptysis are common initial signs. Massive pulmonary hemorrhage is possible, which is a medical emergency. Physical examination reveals tachypnea, tachycardia, cyanosis, pulmonary crackles, and HTN. Diagnosis Blood tests can determine the presence of anti-GBM antibodies. Radioimmunoassays or enzyme-linked immunosorbent assays for anti-GBM antibodies should be performed. Positive results should be con- firmed by a Western blot test. The titer of anti-GBM
Diagnosis Ultrasonography and abdominal CT scans are used in diagnosis. In 80% to 90% of people with ADPKD, cysts are detectable by the age of 20 years via CT scanning. MRI is the best diagnostic study that can visualize cysts in the kidneys and extrarenal organs. The num- ber of MRI-detected cysts considered to be diagnostic is more than 10 in those aged 16 to 40 years. MRI can also rule out renal carcinoma. Genetic testing can be used to determine the type of disease. Serum chemis- try profiles should include calcium and uric acid levels. Urinalysis shows microalbuminuria. Magnetic reso- nance angiography should be used to investigate the possibility of cerebral aneurysms. Treatment Treatment consists of controlling HTN, preventing UTIs, and tolvaptan, a recently approved drug. Tol- vaptan is a vasopressin receptor 2 antagonist that can decrease formation of cysts in the kidney. ACE inhibi- tors or ARBs are commonly used to control blood pres- sure. A low-sodium diet and increased fluid intake of greater than 3 L/day are recommended. Acute flank pain is often associated with kidney cyst hemorrhage, infection, or kidney stones. Chronic pain is usually attributable to cyst enlargement that causes kidney capsule stretching or marked enlargement of the kid- neys. Smoking cessation, maintenance of normal body weight, and daily physical activity are also recom- mended. Reversing metabolic imbalances associated with ESRD is necessary. Conditions such as hyperka- lemia, hypocalcemia, and metabolic acidosis require treatment. UTIs are common in ADPKD, and antibi- otic treatment is needed. Large cysts of the kidney can be surgically decompressed if they cause severe pain. Hemodialysis is necessary if the disease progresses to ESRD. Patients are usually eligible for kidney trans- plant. Development of cysts in the liver, hepatomeg- aly, and liver failure can occur in ADPKD. Patients may require liver transplant. Goodpasture’s Syndrome Antiglomerular basement membrane (anti-GBM) disease is an immunological disease of the kidney. The disorder is an acute, rapidly progressive type of glo- merulonephritis caused by circulating autoantibod- ies. These antibodies are directed against an antigen intrinsic to the collagen in the glomerular basement membrane (GBM). When this disease includes lung involvement, usually in the form of pulmonary hem- orrhage, it is considered a pulmonary-renal syndrome called Goodpasture’s syndrome . Epidemiology Goodpasture’s syndrome is an uncommon disorder that affects 1% to 2% of the U.S. population annu- ally. This autoimmune disease affects the kidney and lungs. It is more common in European Americans than
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