Kidney Specialists May Benefit Some EGPA Patients, Report Suggests

Patricia Inacio, PhD avatar

by Patricia Inacio, PhD |

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Kidney disease is less common among people with eosinophilic granulomatosis with polyangiitis (EGPA), but some patients may experience severe kidney damage and require management by specialists, a case report shows.

The study, “Renal Involvement in Eosinophilic Granulomatosis With Polyangiitis,” was published in the journal Kidney International Reports.

EGPA is a form of ANCA-associated vasculitis (AAV) caused by eosinophils — a kind of immune cell — that attack the small blood vessels of the lungs and respiratory tract, leading to asthma-like symptoms.

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While some patients also experience kidney damage as a result of EGPA, the proportion with kidney disease is much smaller than is found in the other two forms of AAV. Thus, most EGPA patients are never referred to kidney experts.

Researchers in France now reported the case of a 63-year-old man who lost half of his kidney function due to EGPA, showing that “in selected cases, nephrological expertise may play an active role in patient management,” they wrote.

The patient’s clinical history included late-onset asthma, the presence of recurrent nasal polyps, loss of smell, and type 2 diabetes. Three years prior to his admission, his eosinophils blood counts were higher that normal.

On admission, the patient reported fatigue, loss of weight, and muscle weakness, affecting mainly his legs. He also complained of nasal obstruction.

Blood analyses revealed elevated levels of eosinophils and of the kidney function biomarker creatinine (360 micromols per liter of blood, or umol/L; normal range 45–97), leading to a diagnosis of stage 3 acute kidney (renal) injury, using the KDIGO, or Kidney Disease: Improving Global Outcomes, guidelines.

The patient also had protein and traces of blood in his urine, and tested positive for anti-neutrophil cytoplasm antibodies (ANCA), or autoantibodies targeting the myeloperoxidase (MPO) protein.

A kidney biopsy showed signs of inflammation, scarring, and structural and functional changes in the kidneys, leading the clinicians to suspect EGPA with renal involvement.

The patient received methylprednisolone pulse therapy for three days, followed by oral prednisone and intravenous (into-the-vein) cyclophosphamide. He also underwent plasma exchange for 10 days, a procedure that involves replacing a person’s plasma — the noncellular parts of blood — thereby removing ANCAs from the blood.

His high eosinophil levels fell after the beginning of treatment and normalized within four months of the initial referral. Kidney function also improved gradually within 10 days of treatment, though creatinine levels reached a plateau of 140 umol/L.

At his last follow-up, a small amount of protein was still evident in the urine, but no traces of blood.

“This case, together with recent evidence, is at odds with a popular belief stemming from earlier works, according to which renal disease in the context of EGPA is mild and follows a benign course,” the researchers wrote.

“Even if the diagnosis of renal disease is usually made early in EGPA, renal involvement is far from inconsequential, with nearly 20% of patients reaching end-stage renal disease within 4 years of follow-up,” they added.

“Renal vasculitis therefore remains a severe complication in all forms of ANCA-associated vasculitides [inflammation of blood vessels], and EGPA is no exception,” the team concluded.