Case of GPA With High Urine Protein Is Unusual

Somi Igbene, PhD avatar

by Somi Igbene, PhD |

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A man with granulomatosis with polyangiitis — a type of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) — and abnormally raised urine protein levels, a sign of kidney disease, has been described in a recent case report.

Notably, urine protein levels usually are not significantly elevated in people with granulomatosis with polyangiitis (GPA).

“The rapid decline in renal function and quick progression to end-stage renal disease (ESRD) in our patient with AAV is worth noting. This case highlights the importance of clinicians being vigilant and prompt in the diagnosis and management of patients with AAV with nephrotic-range proteinuria to preserve renal function and delay the onset of ESRD,” the authors wrote

The study, “A rare case of nephrotic-range proteinuria in anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis,” was published in the journal Cureus.

GPA is a form of AAV that affects three in one million people in the U.S. While ANCAs — the self-reactive antibodies that drive AAV — may be directed against proteinase 3 (PR3) or myeloperoxidase, GPA is typically associated with PR3-ANCA.

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Patients with GPA typically have few or no antibody or complement proteins (pauci-immune deposits) in their kidneys and lungs. Still, they present with ear, nose, and throat symptoms, as well as respiratory symptoms, and severe kidney disease with raised creatinine and blood in the urine. If evidence of inflammation or damage is present, doctors typically confirm the presence of GPA with a kidney biopsy.

In this study, researchers in the U.S. described the case of a 44-year-old man who had an unusual presentation of GPA — raised urine protein levels.

He had type 2 diabetes and high blood pressure, and had no history of tobacco, alcohol, or illicit substance use. Upon arriving to the hospital,  he reported ear pain, shortness of breath, and fatigue.

Blood tests revealed low hemoglobin and hematocrit levels, elevated white blood cell counts, and high creatinine levels. Hemoglobin is the protein in red blood cells that is responsible for oxygen transport. Hematocrit is the percentage of volume taken up by red blood cells in a blood sample. Creatinine is a marker of kidney dysfunction.

His urine contained abnormally high quantities of protein — a condition known as proteinuria — and moderate amounts of blood (hematuria).

“Usually, patients with GPA and rapidly progressive glomerulonephritis have an elevated plasma creatinine level and urinalysis revealing dysmorphic hematuria, red cell casts, and sub-nephrotic levels of proteinuria,” the researchers wrote. “However, our patient demonstrated only rare [red blood cells] on the urinalysis.”

Doctors initially suspected multiple myeloma, a type of blood cancer, because of his anemia and the presence of certain proteins in his blood. However, a positive test for C-ANCA suggested the presence of AVV and an abdominal and pelvic ultrasound revealed he had chronic kidney disease.

A kidney biopsy showing severe inflammation with areas of extensive damage, consistent with PR3-ANCA vasculitis confirmed the diagnosis.

“The findings in the serum and urine immunofixation and the nephrotic-range proteinuria initially raised suspicion of multiple myeloma. But the C-ANCA screen coming back positive … brought the diagnosis of AAV into the differential. The renal biopsy … helped confirm the diagnosis,” they wrote.

He was given 1g of rituximab, then 14 days later, another 1g of rituximab, along with high-dose intravenous methylprednisolone for three days, followed by a gradual reduction.