Rapidly progressing glomerulonephritis

Rapidly Progressing Glomerulonephritis

Rapidly progressing glomerulonephritis (RPGN), also known as crescentic glomerulonephritis, is a syndrome of the kidney characterized by a rapid loss of renal function, typically over a period of days to weeks. It is a serious condition that can lead to acute kidney failure if not promptly diagnosed and treated.

Pathophysiology

RPGN is characterized by the presence of crescents in the glomeruli, which are formed by the proliferation of parietal epithelial cells and infiltration of monocytes and macrophages. These crescents can obliterate the glomerular space, leading to a rapid decline in kidney function.

The condition can be classified into three main types based on immunofluorescence findings:

• Type I (Anti-GBM disease): Characterized by linear deposits of IgG along the glomerular basement membrane. This type includes Goodpasture's syndrome, where there is also pulmonary involvement.
• Type II (Immune complex-mediated): Characterized by granular deposits of immune complexes. This type is associated with conditions such as lupus nephritis, IgA nephropathy, and post-infectious glomerulonephritis.
• Type III (Pauci-immune): Characterized by the absence of significant immune deposits. This type is often associated with ANCA-associated vasculitis, such as granulomatosis with polyangiitis and microscopic polyangiitis.

Clinical Presentation

Patients with RPGN typically present with symptoms of acute kidney injury, including:

• Oliguria or anuria
• Hematuria (often with red blood cell casts)
• Proteinuria
• Edema
• Hypertension

Systemic symptoms may also be present, depending on the underlying cause, such as hemoptysis in Goodpasture's syndrome or purpura in ANCA-associated vasculitis.

Diagnosis

The diagnosis of RPGN is based on clinical presentation, laboratory findings, and renal biopsy. Key diagnostic steps include:

• Urinalysis: To detect hematuria, proteinuria, and red blood cell casts.
• Serological tests: To identify specific antibodies, such as anti-GBM antibodies or ANCA.
• Renal biopsy: To confirm the presence of crescents and to classify the type of RPGN based on immunofluorescence.

Treatment

The treatment of RPGN depends on the underlying cause but generally involves:

• Immunosuppressive therapy: Such as corticosteroids and cyclophosphamide to reduce inflammation and immune response.
• Plasmapheresis: Particularly in anti-GBM disease, to remove circulating antibodies.
• Supportive care: Including management of hypertension and fluid balance.

Early diagnosis and aggressive treatment are crucial to prevent irreversible kidney damage.

Prognosis

The prognosis of RPGN varies depending on the underlying cause and the promptness of treatment. Without treatment, RPGN can lead to end-stage renal disease. With appropriate therapy, some patients may recover significant kidney function, while others may progress to chronic kidney disease.

Also see

• Glomerulonephritis
• Acute kidney injury
• Chronic kidney disease
• Goodpasture's syndrome
• ANCA-associated vasculitis