Does all vasculitis have renal involvement?

From the Guidelines

No, not all types of vasculitis have renal involvement. The presence of renal involvement varies significantly among different types of vasculitis, with some forms frequently affecting the kidneys and others primarily involving different organ systems. According to the most recent guideline commentary on the management of glomerular diseases 1, kidney involvement is present in up to 75% of patients with ANCA-associated vasculitis (AAV), which includes granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). However, many other vasculitis types, such as giant cell arteritis, Takayasu arteritis, and cutaneous leukocytoclastic vasculitis, primarily affect different organ systems and may not involve the kidneys as frequently.

Some key points to consider include:

• The pattern of vessel involvement (large, medium, or small vessels) and the underlying pathophysiology of each vasculitis type determine which organs are affected.
• When renal involvement does occur, it can range from mild urinary abnormalities to rapidly progressive glomerulonephritis requiring prompt immunosuppressive therapy.
• The diagnostic yield from renal biopsy can be as high as 91.5% in patients with GPA with renal involvement, as noted in earlier recommendations for the management of ANCA-associated vasculitis 1.
• Treatment choice in AAV is influenced by the presence of renal as well as extrarenal vasculitis, highlighting the importance of assessing the extent of organ involvement in these patients.

Given the variability in renal involvement across different types of vasculitis, a thorough diagnostic evaluation, including biopsy when appropriate, is crucial for determining the presence and extent of renal involvement in individual patients. This approach allows for tailored treatment strategies that address the specific needs of each patient, ultimately aiming to minimize morbidity, mortality, and improve quality of life.

From the Research

Renal Involvement in Vasculitis

• Not all forms of vasculitis involve the kidneys, as the frequency of renal involvement varies among different syndromes 2.
• Renal involvement is more frequent in certain types of vasculitis, such as Wegener's granulomatosis and microscopic polyarteritis, while it is uncommon to rare in other forms, like Behçet's disease and relapsing polychondritis 2.
• The vessels affected in renal vasculitis include the renal artery, medium-size renal parenchymal artery, and glomerular involvement, leading to various clinical expressions, such as renovascular hypertension, isolated nonnephrotic proteinuria, interstitial nephritis, and glomerulonephritis 2, 3.

Forms of Vasculitis with Renal Involvement

• Small vessel vasculitis (SVV) is the most frequent vasculitic lesion in the kidney, often presenting as necrotizing crescentic glomerulonephritis 3.
• Medium vessel vasculitis occasionally involves the kidney as necrotizing arteritis, while large vessel vasculitis rarely affects the kidney, usually secondary to ischemia from proximal arterial narrowing 3.
• Specific types of vasculitis, such as Wegener's granulomatosis and microscopic polyarteritis, have a higher frequency of renal involvement, which can lead to rapidly progressive glomerulonephritis and renal failure 2, 4.

Diagnosis and Treatment

• Diagnosis of renal vasculitis is established by a combination of history, clinical manifestations, laboratory findings, imaging techniques, and renal biopsy 2.
• Treatment of renal vasculitis involves the use of immunosuppressive therapy, with plasma exchange as an adjunctive therapy in some cases, and the use of steroid and non-steroid agents 5.
• The choice of treatment depends on the specific type of vasculitis, the severity of renal involvement, and the patient's overall condition, with the goal of inducing remission and preventing long-term renal damage 5, 6.