Question
A 54-year-old man is evaluated for cutaneous vasculitis and peripheral nephropathy. Because of concomitant renal dysfunction, he undergoes a kidney biopsy that shows glomerulonephritis. Cryoglobulins are demonstrated in the peripheral blood. Which of the following laboratory studies should be sent to determine the etiology?
| A. |
Hepatitis B surface antigen
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| B. |
Antineutrophil cytoplasmic antibody (ANCA)
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| C. |
Hepatitis C polymerase chain reaction
|
| D. |
HIV antibody
|
Show Answer
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Correct Answer � C
Explanation
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|
Ans. c
Hepatitis C polymerase chain reaction
The most common manifestations of cryoglobulinemic vasculitis are :
cutaneous vasculitis
Arthritis
peripheral neuropathy
glomerulonephritis (80% – MPGN )
vasculitis of the CNS, gastrointestinal tract, or heart (less common)
Current evidence suggests that in the majority of cases, cryoglobulinemic vasculitis occurs when an aberrant immune response to hepatitis C infection leads to the formation of immune complexes consisting of hepatitis C antigens, polyclonal hepatitis C–specific IgG, and monoclonal IgM rheumatoid factor.
The deposition of these immune complexes in blood vessel walls triggers an inflammatory cascade that results in cryoglobulinemic vasculitis.
The demonstration of circulating cryoprecipitates is a critical component of the diagnosis, and often rheumatoid factors can be found as well.
Because hepatitis C infection is present in the vast majority of patients with cryoglobulinemic vasculitis, an infection should be sought in all patients with this clinical syndrome.
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