what is the next step in management of this ANCA positive microscopic polyangiitis with both renal and pulmonary involvement.

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Published on Feb 21, 2022
CC - A 52-yr-old Hispanic man is found to have rising antineutrophil cytoplasmic autoantibody (ANCA)

HPI- A 52-yr-old Hispanic man was found to have antineutrophil cytoplasmic autoantibody (ANCA)– associated microscopic polyangiitis with both renal and pulmonary involvement. He is treated with oral prednisone and cyclophosphamide. The prednisone is tapered and discontinued after 4 mo, and azathioprine is substituted for cyclophosphamide at 6 mo. His initial serum creatinine was 4.1 mg/dl, and it decreased to a nadir of 1.0 mg/dl after 6 mo of therapy. UA shows resolution of microscopic hematuria and proteinuria. He is now seen for a follow-up examination 2 yr after the initial diagnosis. He is asymptomatic.

CURRENT MEDS - 100 mg of azathioprine daily (maintenance), 15 mg of enalapril daily.

EXAM - His BP is 130/80 mmHg. Physical examination is normal.

LABS - Urinalysis reveals 4 to 5 erythrocytes per high power field, and no proteinuria. The serum creatinine is still 1.0 mg/dl. The erythrocyte sedimentation rate is 20 mm/h (Westergren method). An ANCA test performed 1 wk ago was significantly positive with a titer of 1:128. Previous values have been intermittently positive at low titer.

NEXT STEP IN MANAGEMNET OF PATIENT?

A. Reinstitute cyclophosphamide at 2.0 mg/kg per day; stop azathioprine.
B. Reinstitute cyclophosphamide at 1.0 mg/kg per day; stop azathioprine
C. Continue azathioprine; observe carefully.
D. Discontinue azathioprine; begin mycophenolate mofetil at 1.0 gm twice daily

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