Case 1: Infectious Disease-Associated Syndromes Flashcards
INFECTIOUS DISEASE-ASSOCIATED SYNDROMES
- Poststreptococcal Glomerulonephritis (discussed in acute nephritic syndromes)
- Subacute Bacterial Endocarditis (discussed in acute nephritic syndromes)
HUMAN IMMUNODEFICIENCY VIRUS
● HIV-associated nephropathy is seen after an interval of approximately 2.5 years from discovery of HIV, and many patients have low CD4 counts. Most lesions on renal biopsy show FSGS followed by MPGN.
● Other less common renal lesions include DPGN, lgA nephropathy, MCD, and membranous or mesangioproliferative glomerulonephritis.
● The disease affects up to 10% of HIV-infected patients and is more commonly seen in African-American men than in Caucasians, and in intravenous drug users or homosexuals.
● The FSGS characteristically reveals collapse of the glomerular capillary tuft called collapsing glomerulopathy, visceral epithelial cell swelling, microcystic dilatation of renal tubules, and tubuloreticular inclusions.
● Renal epithelial cells express replicating HIV virus, but host immune responses also play a role in the pathogenesis. MPGN and DPGN have been reported more commonly in HIV-infected Caucasians and in patients co-infected with hepatitis B or C. HIV-associated TTP has also been reported.
● HIV patients with FSGS typically present with nephrotic-range proteinuria and hypoalbuminemia, but unlike patients with other etiologies for nephrotic syndrome, they do not commonly have hypertension, edema, or hyperlipidemia.
● Renal ultrasound also reveals large, echogenic kidneys, and renal function in some patients declines rapidly.
● Treatment with inhibitors of the renin-angiotensin system decreases the proteinuria. Although evidence from large well-designed clinical trials is lacking, many feel that effective antiretroviral therapy benefits both the patient and the kidney.
● Dismal survival once renal failure is reached has improved, and many centers now offer renal allografts to select HIV patients.
SYPHILIS
● Secondary syphilis, with rash and constitutional symptoms, develops weeks to months after the chance first appears and occasionally presents with the nephrotic syndrome from MGN caused by subepithelial immune deposits containing treponemal antigens.
● The diagnosis is confirmed with non-treponemal and treponemal tests for Treponema pallidum. The renal lesion responds to treatment with penicillin or an alternative drug, if allergic. Additional testing for other sexually transmitted diseases is an important part of disease management.
HEPATITIS B AND C
● Chronic hepatitis B infection can be associated with polyarteritis nodosa, more commonly in adults than children.
● Typically, however, infected patients only present with microscopic hematuria, non nephrotic or nephritic-range proteinuria, and hypertension.
● Alternatively, the hepatitis B carrier state can produce a MGN that is more common in children than adults or MPGN that is more common in adults than in children. Renal histology is indistinguishable from idiopathic MGN or Type I MPGN.
● There are no good treatment guidelines, but interferon and lamivudine have been used to some effect in small studies. Children have a good prognosis, with 66% achieving spontaneous remission within 3 years.
● In contrast, 30% of adults have renal insufficiency and 10% have renal failure 5 years after diagnosis. Up to 30% of patients with chronic hepatitis C infection have some renal manifestations.
● Patients often present with cryoglobulinemia and nephrotic syndrome, microscopic hematuria, abnormal liver function tests, depressed C3 levels, anti-HCV antibodies, and viral RNA in the blood.
● The renal lesions most commonly seen, in order of decreasing frequency, are cryoglobulinemic glomerulonephritis, MGN, and Type I MPGN. Treatment aims at reducing the level of the infection.
