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Essentials of Diagnosis
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- HIV-associated nephropathy (HIVAN) is a distinct and separate pathology with a unique combination of collapsing focal segmental glomerulosclerosis (FSGS), tubuloreticular inclusion bodies, microcystic dilation of renal tubules, and interstitial inflammation found in HIV-infected individuals.
- While HIVAN should be suspected in any HIV-infected person of African descent with proteinuria and decreased glomerular filtration rate (GFR), definitive diagnosis can be made only by renal biopsy.
- At-risk HIV-positive patients should be tested for proteinuria or decreased GFR to allow earlier detection of HIVAN.
- HIVAN is caused by expression of HIV-1 genes in renal epithelial cells.
- Highly active antiretroviral therapy (HAART) is the primary mode of treatment to retard progression of glomerular filtration decline and proteinuria.
- The diagnosis of HIVAN is an indication to begin HAART regardless of CD4 or viral counts.
- Angiotensin-converting enzyme (ACE) inhibitors and steroids may be of benefit in selected patients.
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General Considerations
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At the onset of the HIV epidemic, little was known concerning the ability of the virus to cause organ-specific pathology. By 1984, it became apparent that there was a renal syndrome associated with HIV infection that was characterized by severe proteinuria and rapidly progressive renal failure. Proteinuria was frequently severe with levels of protein excretion as high as 10 g daily. Patients were often asymptomatic until features of renal failure became manifest. As opposed to similar glomerulopathies, the nephropathy associated with HIV infection did not often result in severe hypertension or edema. On ultrasound imaging of the kidneys, nephromegaly was a common finding with increased kidney weight seen on autopsy. Renal biopsy of these patients revealed the presence of focal glomerulosclerosis, tubular microcystic dilation, and tubulointerstitial inflammation and fibrosis.
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Now widely accepted to be a distinct renal disease, HIVAN does not affect all populations equally. In the United States, HIVAN is the third leading cause of end-stage renal disease (ESRD) in African-Americans between the ages of 25 and 64 years. International studies evaluating HIV-infected patients with proteinuria corroborate the U.S. data. Two studies in Thailand and Italy did not detect any cases of HIVAN among HIV-infected patients who underwent renal biopsy to evaluate the cause of proteinuria. Neither of these studies included any patients of African descent. A South African study, however, evaluated 30 patients with proteinuria and 7 patients with microalbuminuria. Renal biopsies revealed that 83% of the patients had pathology consistent with HIVAN, including six out of the seven patients with microalbuminuria. Moreover, ESRD due to HIVAN is 12.2 times more likely to occur in African-Americans than in whites and has the strongest racial predisposition of any form of acquired renal disease leading to ESRD.
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Prior to the availability of HAART, the clinical course of HIVAN was characterized by a rapid decline of renal function resulting in the need for renal replacement therapy within weeks to months after diagnosis. The prognosis of these patients was dismal, approximately 1 year once on dialysis. ...