Nephritic syndrome

Overview

Nephritic syndrome is a clinical condition characterized by inflammation of the glomeruli, the filtering units of the kidneys. This inflammation leads to impaired kidney function and a group of symptoms that typically include hematuria (blood in the urine), proteinuria (protein in the urine, though less than in nephrotic syndrome), reduced glomerular filtration rate, hypertension, and varying degrees of edema. Nephritic syndrome can occur at any age but is particularly common in children and young adults following certain infections.

Nephritic syndrome is distinct from nephrotic syndrome, although both involve kidney dysfunction. While nephrotic syndrome is characterized primarily by massive proteinuria and hypoalbuminemia, nephritic syndrome is dominated by hematuria and signs of glomerular inflammation. Prompt recognition and management are essential to prevent progression to chronic kidney disease or end-stage renal failure.

Causes

Nephritic syndrome can be caused by a wide variety of underlying conditions, most of which involve immune-mediated inflammation of the glomeruli. These causes can be broadly categorized into primary glomerular diseases and systemic diseases affecting the kidneys.

Primary Glomerular Diseases

• Post-streptococcal glomerulonephritis: Occurs after a streptococcal throat or skin infection, especially in children

• IgA nephropathy (Berger’s disease): Recurrent episodes of hematuria, often following upper respiratory infections

• Membranoproliferative glomerulonephritis: Involves both nephritic and nephrotic features

• Rapidly progressive glomerulonephritis (RPGN): A severe form of nephritic syndrome that can lead to rapid renal failure

Secondary/Systemic Diseases

• Lupus nephritis: Associated with systemic lupus erythematosus (SLE)

• Goodpasture syndrome: Autoimmune disease affecting lungs and kidneys

• Vasculitis: Such as granulomatosis with polyangiitis or microscopic polyangiitis

• Endocarditis or other infections: Can lead to immune complex-mediated glomerulonephritis

Symptoms

The presentation of nephritic syndrome varies depending on the cause and severity of inflammation but typically includes the following features:

• Hematuria: Presence of blood in the urine; may appear as cola-colored or tea-colored urine

• Proteinuria: Protein in the urine, usually mild to moderate (less than 3.5 g/day)

• Hypertension: Elevated blood pressure due to fluid retention and reduced kidney function

• Edema: Swelling, typically in the face (especially periorbital), legs, or ankles

• Oliguria: Decreased urine output

• Fatigue and malaise: Due to reduced kidney function and systemic inflammation

• Headache: Often secondary to high blood pressure

Diagnosis

The diagnosis of nephritic syndrome is based on clinical findings, laboratory tests, and sometimes kidney biopsy. A thorough history and physical examination are critical for identifying the underlying cause.

• Urinalysis: Reveals hematuria, red blood cell casts (a hallmark of glomerular inflammation), and proteinuria

• Blood tests:

  • Elevated serum creatinine and BUN indicating impaired kidney function

  • Complement levels (C3, C4) to assess for immune-mediated causes

  • Autoantibodies (ANA, anti-dsDNA, ANCA, anti-GBM) to screen for lupus, vasculitis, or Goodpasture syndrome

• Throat or skin swabs: To detect recent streptococcal infection in suspected post-infectious cases

• Renal ultrasound: May show kidney size and structure; useful in ruling out obstruction

• Kidney biopsy: Often required to confirm the diagnosis and assess the degree of glomerular damage

Treatment

The treatment of nephritic syndrome depends on the underlying cause, severity of kidney involvement, and presence of systemic disease. Supportive management is essential in all cases, while disease-specific therapy may be required for autoimmune or rapidly progressive conditions.

Supportive Care

• Blood pressure control: ACE inhibitors or ARBs are commonly used

• Diuretics: For managing fluid overload and edema

• Sodium and fluid restriction: Helps control blood pressure and swelling

• Monitoring renal function: Regular assessment of serum creatinine, electrolytes, and urine output

Disease-Specific Therapy

• Antibiotics: If active streptococcal or other infections are present

• Immunosuppressive therapy: Such as corticosteroids, cyclophosphamide, or rituximab in cases of lupus nephritis, vasculitis, or RPGN

• Plasmapheresis: May be used in Goodpasture syndrome or severe RPGN with anti-GBM antibodies

Prognosis

The prognosis of nephritic syndrome varies widely depending on the underlying cause, patient age, and response to treatment. Many cases of post-infectious nephritic syndrome in children resolve spontaneously with full recovery. In contrast, rapidly progressive forms or those associated with systemic autoimmune diseases may lead to chronic kidney disease or end-stage renal failure if not promptly and aggressively treated.

Regular follow-up with a nephrologist, blood pressure control, and close monitoring of kidney function are essential for long-term management. Early intervention and appropriate therapy can significantly improve outcomes and reduce the risk of complications.