CORRECT ANSWER IS C
This patient has ANCA positive microscopic polyangiitis and is in a clinical remission, with normal proteinuria and normal renal function. The remission has been induced with sequential cyclophosphamide and azathioprine therapy and the only outward manifestation of possible continued “activity” of disease is a positive ANCA serology and persistent mild microscopic hematuria. While persistence of positive ANCA serology, despite clinical remission may herald a clinical relapse in some patients many exceptions to this finding have been described. ANCA titers are not a reliable marker of disease activity. Most experts agree that it is better to carefully follow patients with clinically quiescent disease who are serologically positive and to reinstitute therapy at the first sign of a clinical relapse, rather than to expose patients to unnecessary and potentially toxic therapy, based solely on a serologic finding, which may represent a “false positive” with respect to “active” disease.
Nevertheless, patients who are serologically “active” may be at increased risk of relapse, especially when they develop an intercurrent infection. Larger cohort studies have found that a rise in ANCA titer is not consistently predictive of a disease flare, with discordant ANCA titers and disease activity occurring in as many as 60 percent of patients.
Experts recommend to closely monitor patients with rising ANCA titers but avoid treatment changes unless there are clear clinical signs of active disease. The following varied approaches have been adopted by expert ANCA centers. A) measure an ANCA titer when a patient attains remission and then repeat the titer if a flare is suspected. B) monitor ANCA at regular intervals, and patients who have a rise in serum ANCA titers are monitored more frequently for early signs of clinical relapse) Do not monitor ANCA titers at all. However, patients should not be treated for relapse based solely upon ANCA titers. If a patient was ANCA positive during a period of active disease, a persistently ANCA-negative status is consistent with, but not absolute proof of, remission.
Mycophenolate mofetil is an alternative maintenance gent for patients who do not respond to, cannot tolerate, or have contraindications to Azathioprine.
REFERENCE
Accurate Relapse Prediction in ANCA-Associated Vasculitis–the Search for the Holy Grail (nih.gov)
Relapse in Anti-Neutrophil Cytoplasm Antibody (ANCA)–Associated Vasculitis – ScienceDirect
