American Board of Internal Medicine (ABIM) Certification Practice Exam

What disease is most commonly associated with IgA nephropathy upon kidney biopsy?

1. Systemic lupus erythematosus

2. Rheumatoid arthritis

3. Henoch-Schönlein Purpura

4. Granulomatosis with polyangiitis

The correct answer is: Henoch-Schönlein Purpura

IgA nephropathy, also known as Berger’s disease, is often associated with Henoch-Schönlein Purpura (HSP), particularly in children. HSP is a small-vessel vasculitis characterized by a tetrad of symptoms: palpable purpura, often on the buttocks and legs, arthralgia, abdominal pain, and renal involvement. The pathophysiology involves deposition of IgA-complexes in the glomeruli, which leads to inflammation and damage. In HSP, kidney involvement is a common manifestation as it shares immunological mechanisms with IgA nephropathy. In contrast, systemic lupus erythematosus, rheumatoid arthritis, and granulomatosis with polyangiitis, while they can affect the kidneys, are associated with different types of glomerular diseases, such as lupus nephritis or crescentic glomerulonephritis, which do not specifically relate to the deposition of IgA in the same way that IgA nephropathy does. Therefore, the connection between IgA nephropathy and Henoch-Schönlein purpura is the strongest among the answer choices given.