Nephritic syndrome

Nephritic syndrome refers to a group of glomerular disorders characterized by inflammation of the glomeruli, resulting in leakage of blood and moderate amounts of protein into urine, reduced glomerular filtration rate (GFR), and fluid retention.

Glomerular disease may arise from:

• Primary renal disease, or

• Secondary systemic disorders affecting the kidneys.

Unlike nephrotic syndrome, nephritic syndrome is primarily an inflammatory process, often presenting acutely and potentially progressing to acute kidney injury (AKI) if not promptly managed.

Pathophysiology

Inflammation of the glomerular capillary walls leads to:

1. Damage to glomerular filtration barrier

2. Leakage of red blood cells → haematuria

3. Reduced filtration → decreased GFR

4. Sodium and water retention

5. Hypertension and oedema

Immune-mediated injury is the most common mechanism involving:

• Immune complex deposition

• Complement activation

• Cellular inflammation

Common Causes

Primary Glomerular Diseases

• Acute post-streptococcal glomerulonephritis (APSGN)

• IgA nephropathy

• Rapidly progressive glomerulonephritis

• Membranoproliferative glomerulonephritis

Secondary Causes

• Systemic lupus erythematosus

• Vasculitis

• Infective endocarditis

• Hepatitis B or C infection

• Henoch–Schönlein purpura

• Goodpasture syndrome

Risk Factors

• Recent streptococcal throat or skin infection

• Autoimmune diseases

• Chronic infections

• Genetic susceptibility

• Male sex (some forms)

• Childhood or young adulthood

• Exposure to nephrotoxic agents

Signs and Symptoms

Urinary Manifestations

• Cola-colored or smoky urine

• Visible or microscopic haematuria

• Mild to moderate proteinuria

• Reduced urine output (oliguria)

Fluid Retention Features

• Periorbital oedema

• Peripheral oedema

• Rapid weight gain

Systemic Features

• Hypertension

• Fatigue

• Headache

• Shortness of breath

• Nausea and vomiting

Severe Presentations

• Pulmonary oedema

• Hypertensive emergency

• Acute kidney injury

• Encephalopathy

Diagnostic Criteria

Diagnosis is based on clinical and laboratory findings:

• Haematuria

• Proteinuria

• Reduced GFR or rising serum creatinine

• Hypertension

• Oedema

Investigations

Baseline Investigations

• Renal function tests (urea, creatinine, electrolytes)

• Urinalysis (RBCs, protein, casts)

• Urine microscopy (RBC casts)

• Urine culture

• Complete blood count

Immunological and Etiological Tests

(Usually performed at tertiary level)

• Complement levels (C3, C4)

• Antistreptolysin O titre (ASO)

• ANA and anti-dsDNA

• ANCA

• Anti-GBM antibodies

• Hepatitis B and C screening

• HIV testing

Imaging

• Renal ultrasound (kidney size and obstruction)

Definitive Diagnosis

• Renal biopsy when:

  • Rapid deterioration of renal function

  • Unclear diagnosis

  • Suspected rapidly progressive glomerulonephritis

  • Adult-onset nephritic syndrome

Important Note:Definitive treatment depends entirely on identifying the underlying cause.

Management

Management focuses on:

• Stabilization

• Control of fluid overload

• Blood pressure management

• Treatment of underlying disease

• Prevention of renal failure

Pharmacological Management

1. Fluid Overload

• Furosemide 80 mg IV bolus

  • May repeat depending on response

2. Hypertension Management

If:

• Diastolic BP >100 mmHgOR

• Systolic BP >150 mmHg

→ Amlodipine 5 mg orally

Additional antihypertensives may be required under specialist care.

3. Cause-Specific Therapy (Specialist Guided)

May include:

• Antibiotics (post-infectious causes)

• Corticosteroids

• Immunosuppressants

• Plasmapheresis (severe immune disease)

• ACE inhibitors/ARBs after stabilization

4. Management of Complications

• Dialysis for severe renal failure

• Treatment of hyperkalaemia

• Management of pulmonary oedema

Non-Pharmacological Management

• Administer oxygen if respiratory distress present

• Nurse patient in semi-Fowler’s position

• Strict salt restriction

• Restrict potassium-containing foods

• Fluid restriction:

  10 mL/kg/day + visible fluid losses

• Daily weight monitoring

• Input–output chart monitoring

• Avoid nephrotoxic medications

Complications

• Acute kidney injury

• Chronic kidney disease

• Hypertensive crisis

• Pulmonary oedema

• Hyperkalaemia

• Uraemia

• End-stage renal disease

Prevention

Preventive strategies include:

• Early treatment of streptococcal infections

• Control of autoimmune diseases

• Infection prevention

• Avoidance of nephrotoxic drugs

• Blood pressure control

• Regular monitoring in high-risk patients

• Early referral to specialist care

Referral Criteria

Immediate referral to nephrologist or tertiary hospital if:

• Rapid decline in renal function

• Severe hypertension

• Oliguria or anuria

• Pulmonary oedema

• Suspected rapidly progressive glomerulonephritis

• Electrolyte imbalance

• Need for renal biopsy or dialysis

Patient Education

Patients and caregivers should be advised to:

• Monitor urine color and output

• Restrict salt intake

• Adhere strictly to medications

• Seek urgent care for breathlessness or reduced urine

• Avoid herbal or over-the-counter nephrotoxic drugs

• Attend follow-up renal assessments

Prognosis

Outcome varies depending on cause:

• Post-streptococcal nephritis → usually good recovery (especially in children)

• Autoimmune nephritis → variable progression

• Rapidly progressive forms → may lead to permanent renal failure without early treatment