Goodpasture’s disease is an autoimmune condition
Pathophysiology
1) results from formation of antibody against specific component of connective tissue; in this case, type 4 collagen 2) type 2 hypersensitivity reaction 3) autoantibody binds to basement membranes in lung alveoli and glomeruli
Signs and Symptoms
1) presenting sign is usually hemoptysis (coughing up blood) 2) weakness 3) dyspnea (shortness of breath) 4) hematuria (blood in the urine) 5) urinary sediment 6) glomerulonephritis presents on average 3 months after lung disease (in some patients, renal disease remains clinically silent
Characteristic Test Findings
Laboratory – 1) hypoxia and respiratory alkalosis during episodes of hemorrhage 2) microcytic iron-deficiency anemia (low red blood cell count) 3) antibodies against glomerular basement membrane (95%) 4) positive ANCA (20%) 5) diagnosis by kidney or lung biopsy Radiology – 6) fluffy infiltrates on chest radiograph (X-ray)
Histology/Gross Pathology
Lung – 1) extensive pulmonary intra-alveolar hemorrhage 2) thickened alveolar septa with interstitial fibrosis 3) alveoli are lined by type II pneumocytes 4) linear deposition of IgG Kidney – 5) glomerularnephritis with linear deposition of IgG 6) crescent formation
Associated Conditions
1) HLA-DRw2 2) onset of lung component is associated with viral upper respiratory tract infection and cigarette smoking
Biochemistry
1) anti-basement membrane antibodies cause a local inflammatory response 2) local complement activation and neutrophil recruitment 3) damage to tissue can result from formation of membrane attack complex
Inheritance/Epidemiology
1) typically occurs in young men 2) 50% 2 year survival if only lung symptoms are present (worse if kidney symptoms are also present 3) male to female, 6:1 4) has a second peak of incidence at age 60-70 years, with equal sex distribution
Treatment
1) corticosteroids 2) cyclophosamide 3) azathioprine 4) plasmapheresis 5) if end-stage renal failure transplantation is performed 6) prompt initiation of treatment is important because damage does not reverse
Tips for USMLE
1) if question mentions diffuse linear staining of glomerular basement membrane for IgG, think Goodpasture’s or diabetic glomerulonephritis 2) other causes of pulmonary-renal disease are Henoch-Schonlein purpura, Wegener’s granulomatosis, polyarteritis nodosa, Legionnaire’s disease, and renal vein thrombosis with pulmonary embolism
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