Crescentic glomerulonephritis

Crescentic Glomerulonephritis

Crescentic glomerulonephritis, also known as rapidly progressive glomerulonephritis (RPGN), 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

Crescentic glomerulonephritis is defined 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 compress the glomerular tuft and disrupt normal 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 immunoglobulins and complement. 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 crescentic glomerulonephritis 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 crescentic glomerulonephritis is confirmed by renal biopsy, which reveals the presence of crescents in the majority of glomeruli. Immunofluorescence and electron microscopy are used to further classify the type of glomerulonephritis.

Laboratory tests may include:

• Serum creatinine and blood urea nitrogen (BUN) to assess kidney function
• Urinalysis to detect hematuria and proteinuria
• Serological tests for anti-GBM antibodies, ANCA, and complement levels

Treatment

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

• Immunosuppressive therapy:High-dose corticosteroids and cyclophosphamide are commonly used to reduce inflammation and immune response.
• Plasmapheresis:Particularly in anti-GBM disease, to remove circulating antibodies.
• Supportive care:Management of hypertension, fluid balance, and electrolyte disturbances.

Early and aggressive treatment is crucial to prevent irreversible kidney damage.

Prognosis

The prognosis of crescentic glomerulonephritis varies depending on the underlying cause and the promptness of treatment. Without treatment, the condition can rapidly progress to end-stage renal disease. With appropriate therapy, some patients may achieve partial or complete recovery of renal function.

Also see

• Glomerulonephritis
• Nephrotic syndrome
• Acute kidney injury
• Chronic kidney disease