Case presentation
An 81-year-old female patient with a 5-year history of microscopic
hematuria presented to our institution in May 2017 with complaints of
gross hematuria and fatigue persisting for 2 months, and nausea and
anorexia persisting for 10 days, but with no fever, edema, oliguria,
weight loss, or hemoptysis. She had a history of diabetes mellitus for
20 years and a history of hypertension for 9 years.
Physical examination revealed blood pressure (BP) at 120/80 mmHg, normal
sinus rhythm, moderate anemic appearance, and moist rales in her left
lower lung. Laboratory results indicated rapidly progressive
deterioration of renal function. Serum creatinine (SCr) was 97.6 μmol/L
on February 21, 254.2 μmol/L on April 28, and 276.1 μmol/L on May 2,
2017 (range: 41–111 μmol/L). Urinalysis showed 3+ blood, 2+ protein,
and full-visual-field red blood cells (RBCs) per high-power field with
60% dysmorphic RBCs. Serum albumin was 38.4 g/L, and 24-hour urinary
protein quantitation was 4.26 g. Hemoglobin (Hb) was 76 g/L, the white
blood cell count (WBC) was 7.54 × 109/L, platelet
count (PLT) was 177 × 109/L, and erythrocyte
sedimentation rate (ESR) was 69 mm/h (range: 0–15 mm/h). The
concentrations of plasma C3 (54.1 mg/dl) and C4 (1.56 mg/dl) were
significantly reduced (range: 90–180 mg/dl and 10–40 mg/dl,
respectively). Anti-double-stranded deoxyribonucleic acid (anti-dsDNA),
anti-Smith (anti-Sm), anti-Sjogren syndrome A antibody (anti-SSA), and
anti-Sjogren syndrome B (anti-SSB) antibodies were all negative with
weakly positive antinuclear antibody (1:160). Test results for
rheumatoid factor, C-reactive protein (CRP), and serum cryoglobulin were
normal. ANCA enzyme immunoassay revealed a perinuclear staining pattern
(p-ANCA) and serum anti-myeloperoxidase (MPO) antibody of 119 units/ml
(normal: < 20 U/ml), whereas anti-protease 3 and serum
anti-glomerular basement membrane antibody concentrations were normal.
The results of infectious studies for hepatitis C (HCV), hepatitis B
(HBV), and human immunodeficiency virus (HIV) were negative. Renal
ultrasonography showed normally-sized kidneys and increased cortical
echogenicity. Chest computed tomography (CT) indicated a small nodule in
the superior lobe of the right lung and a ground-glass opacity nodule in
the superior lobe of the left lung (Fig. 1).
We diagnosed AAV; renal biopsy was not performed because the patient
declined this procedure.