Acute glomerulonephritis

Background

Acute glomerulonephritis (AGN) is a syndrome characterized by sudden onset of glomerular inflammation, often due to immune-mediated damage. It may follow infections (e.g., post-streptococcal), be part of systemic diseases (e.g., lupus, vasculitis), or be primary renal pathology (e.g., IgA nephropathy). It can lead to rapid loss of kidney function if not promptly recognized.

Clinical Features

Hematuria (often gross or “tea/cola-colored”)

Proteinuria (may be subnephrotic or nephrotic range)

Edema (especially periorbital or dependent)

Hypertension

Oliguria or anuria

Fatigue, malaise

In some cases: fever, arthralgia, or rash (if systemic disease)

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Differential Diagnosis

Nephrotic syndrome (e.g., minimal change disease)

Acute tubular necrosis

Interstitial nephritis

Hemolytic uremic syndrome (HUS)

Thrombotic thrombocytopenic purpura (TTP)

Urinary tract infection (for hematuria/proteinuria)

Urolithiasis or trauma (for hematuria)

Evaluation

Workup

Urinalysis: Hematuria, red blood cell casts, proteinuria

Blood tests:

BUN/Creatinine

CBC (anemia, leukocytosis)

Complements (C3, C4)

Antistreptolysin-O (ASO) titer, anti-DNase B

ANA, ANCA, anti-GBM antibodies

Renal ultrasound: Evaluate for obstruction or size changes

Kidney biopsy: If unclear diagnosis, severe presentation, or rapid progression

Diagnosis

Diagnosis is clinical, supported by lab findings of kidney injury with hematuria, proteinuria, and often low complement levels. Serologies may point to the underlying cause. Biopsy provides definitive diagnosis when needed.

Management

Supportive care: Salt and fluid restriction, diuretics for edema, antihypertensives

Treat underlying cause:

Post-infectious: usually self-limited; antibiotics if infection active

Lupus nephritis: corticosteroids, immunosuppressants

ANCA vasculitis or anti-GBM disease: steroids, cyclophosphamide, plasmapheresis

Nephrology consult for all but mildest cases

Disposition

Admit if: significant renal impairment, uncontrolled hypertension, volume overload, rapidly progressive features, or systemic disease

Outpatient management may be possible for stable patients with close nephrology follow-up