Introduction
Nephritic syndrome is a clinical syndrome resulting from inflammation of the glomeruli, leading to impaired renal filtration. It is characterised by haematuria, mild-to-moderate proteinuria, oedema, hypertension, and varying degrees of renal impairment. Unlike nephrotic syndrome, in which protein loss predominates, nephritic syndrome reflects glomerular injury due to immune-mediated inflammation, leading to red cell leakage and reduced glomerular filtration.
In Ghana, as in many developing countries, post-streptococcal glomerulonephritis (PSGN) remains the most common cause in children. However, other glomerulonephritides such as lupus nephritis and IgA nephropathy are also encountered.
Understanding nephritic syndrome is important because timely diagnosis and appropriate management can prevent progression to chronic kidney disease.
Epidemiology
Nephritic syndrome can occur at any age but is most common in school-aged children between 5 and 12 years.
- Sex: Slight male predominance (M:F ≈ 2:1).
- Geography: Higher prevalence in areas with poor sanitation, overcrowding, and high incidence of streptococcal skin or throat infections.
- Seasonal variation: Cases often peak following outbreaks of streptococcal infections, especially during the dry or cold season.
In Ghanaian children, acute post-streptococcal glomerulonephritis (APSGN) accounts for the majority of nephritic presentations.
Aetiology and Classification
Nephritic syndrome can be classified according to clinical course (acute, rapidly progressive, or chronic) or underlying aetiology (primary renal vs secondary systemic causes).
Primary Glomerular Causes
- Acute post-streptococcal glomerulonephritis (APSGN):
The classic cause in children, occurring 1–3 weeks after group A β-haemolytic streptococcal pharyngitis or skin infection (impetigo).
- IgA nephropathy (Berger’s disease):
Characterised by recurrent haematuria, often following upper respiratory tract infection.
- Membranoproliferative glomerulonephritis (MPGN):
Chronic immune complex–mediated inflammation causing persistent haematuria and proteinuria.
- Rapidly progressive glomerulonephritis (RPGN):
Severe form with crescent formation in glomeruli and rapid loss of renal function.
2. Secondary Glomerular Causes
- Systemic lupus erythematosus (SLE): Immune complex deposition in glomeruli.
- Henoch-Schönlein purpura (HSP): IgA-mediated vasculitis involving the kidneys.
- Infections: Hepatitis B/C, malaria, HIV.
- Endocarditis or shunt nephritis: Chronic infection leading to immune complex glomerulonephritis.
Pathophysiology
Nephritic syndrome arises from inflammation and proliferation within the glomeruli, usually mediated by immune-complex deposition or autoantibodies.
The general sequence is as follows:
- Immune complex formation (e.g., streptococcal antigens with antibodies).
- Deposition in glomerular capillaries and activation of the complement system.
- Inflammatory response → neutrophil and macrophage infiltration.
- Glomerular injury → capillary wall thickening, cellular proliferation, and reduced surface area for filtration.
- Reduced glomerular filtration rate (GFR) → salt and water retention → oedema and hypertension.
- Leakage of red cells and some protein into urine → haematuria and mild proteinuria.
Clinical Features
History
The onset is usually acute, developing within days to weeks following a streptococcal throat or skin infection.
Key presenting symptoms:
- Haematuria: Brown, smoky, or cola-coloured urine.
- Oliguria: Decreased urine output due to reduced GFR.
- Facial puffiness: Particularly periorbital oedema, worse in the morning.
- Mild generalized oedema.
- Headache or visual disturbances: Due to hypertension.
- History of sore throat or impetigo 1–3 weeks prior to illness.
Physical Examination
- Oedema: Usually mild, periorbital, and pedal.
- Blood pressure: Elevated in most cases (may be severe).
- Urine colour: Dark, tea-coloured urine.
- Signs of volume overload: Raised jugular venous pressure, basal crepitations.
- Other findings: Pallor (anaemia), mild hepatomegaly.
Differential Diagnosis
| Nephrotic syndrome |
Marked oedema, massive proteinuria, normal complement |
| Haemolytic uraemic syndrome |
Triad of anaemia, thrombocytopenia, and renal failure following diarrhoea |
| IgA nephropathy |
Recurrent macroscopic haematuria after respiratory infection |
| SLE nephritis |
Photosensitive rash, arthritis, positive ANA |
| Acute interstitial nephritis |
Drug exposure, eosinophiluria |
Investigations
Urine Tests
- Urinalysis:
- Haematuria: Dysmorphic RBCs and red cell casts are diagnostic.
- Proteinuria: Usually mild to moderate (1–2+).
- Specific gravity: Often raised due to oliguria.
- Microscopy: RBC casts, WBCs.
Blood Tests
- Renal function: Elevated urea and creatinine indicate impaired filtration.
- Complement levels (C3): Low in post-streptococcal GN, normal in IgA nephropathy.
- ASO titre / anti-DNase B: Elevated after streptococcal infection.
- Serum electrolytes: May show hyperkalaemia or hyponatraemia.
- Full blood count: Mild anaemia, leukocytosis possible.
- Antinuclear antibody (ANA): For suspected lupus nephritis.
Imaging
- Renal ultrasound: Normal or slightly enlarged kidneys with increased echogenicity.
- Chest X-ray: Pulmonary oedema or cardiomegaly from volume overload.
Kidney Biopsy
Indications include:
- Atypical course (no recovery after 2–3 weeks)
- Persistent renal dysfunction
- Gross proteinuria (>3 g/day)
- Absence of low complement
- Suspected lupus nephritis or RPGN
Diagnosis
Diagnosis is based on the presence of the following:
- Haematuria (microscopic or macroscopic)
- Oliguria with elevated urea and creatinine
- Mild-to-moderate proteinuria
- Hypertension
- History of preceding infection
Management
Treatment of nephritic syndrome is mainly supportive, aimed at controlling hypertension, oedema, and preventing complications. The underlying cause guides specific therapy.
General Measures
- Hospital admission for monitoring of blood pressure, urine output, and renal function.
- Bed rest during the acute phase to reduce workload on kidneys.
- Fluid restriction to match output + insensible loss (usually 400–600 mL/m²/day).
- Sodium restriction to prevent oedema and hypertension.
Control of Oedema
- Loop diuretics (furosemide 1–2 mg/kg) if the child is not oliguric.
- Avoid excessive diuresis in oliguric states to prevent hypovolemia.
- Fluid overload with pulmonary oedema may require frusemide + antihypertensive therapy or dialysis.
Hypertension Management
Hypertension in nephritic syndrome is mainly volume-dependent.
First-line: Loop diuretics.
If persistent: Add nifedipine or hydralazine.
Severe hypertension or hypertensive encephalopathy: Use IV antihypertensives cautiously (e.g., labetalol infusion).
Infection Management
- If there is an ongoing streptococcal infection, give benzathine penicillin or amoxicillin.
- Antibiotic prophylaxis is not usually required once the infection has cleared.
Dietary Advice
- Salt restriction until oedema and hypertension resolve.
- Protein intake: Normal for age (avoid restriction unless renal failure develops).
- Potassium restriction if hyperkalaemia occurs.
Dialysis Indications
Dialysis may be required if there is: - Refractory fluid overload.
- Severe hyperkalaemia
- Rising urea/creatinine
- Uremic encephalopathy or seizures
Specific Therapy
Post-Streptococcal Glomerulonephritis
- Mainly supportive care.
- Prognosis excellent; most recover fully within 6–8 weeks.
- Persistent proteinuria or haematuria may last months.
IgA Nephropathy and MPGN
- Often chronic; may need ACE inhibitors or immunosuppressants (prednisolone, azathioprine).
- Regular follow-up of renal function is essential.
Lupus Nephritis
- Requires systemic corticosteroids and immunosuppressive therapy (mycophenolate mofetil or cyclophosphamide).
- Managed in collaboration with a paediatric nephrologist.
Rapidly Progressive Glomerulonephritis
- Aggressive management with high-dose corticosteroids, cyclophosphamide, and sometimes plasma exchange.
- Early treatment may prevent irreversible renal failure.
Complications
- Hypertensive encephalopathy: Seizures, vomiting, blurred vision.
- Acute renal failure: Due to severe glomerular inflammation.
- Fluid overload: Pulmonary oedema or heart failure.
- Electrolyte imbalances: Hyperkalaemia, hyponatraemia.
- Chronic kidney disease: From unresolved inflammation.
Prognosis
Most children with post-streptococcal nephritic syndrome recover completely.
- Microscopic haematuria may persist for up to 6–12 months.
- Renal function returns to normal in >95% of cases.
- Poor prognostic factors: Persistent hypertension, heavy proteinuria, reduced complement for >8 weeks, and histologic evidence of crescentic GN.
Chronic or secondary causes (e.g., lupus, MPGN) may progress to end-stage kidney disease if not adequately managed.
Prevention
- Early diagnosis and treatment of streptococcal infections (pharyngitis, impetigo).
- Improved sanitation and hygiene to reduce transmission.
- Community health education to promote prompt medical attention for children with swelling or dark urine.
- Regular follow-up for children with known glomerular diseases.
Conclusion
Nephritic syndrome in children, particularly post-streptococcal glomerulonephritis, remains a significant cause of acute kidney disease in Ghana. It typically follows streptococcal infection and manifests with haematuria, oedema, and hypertension. While most cases resolve spontaneously with supportive care, early recognition and careful monitoring are essential to prevent complications and chronic kidney damage. A solid grasp of its pathophysiology and management principles is crucial for medical students and paediatric practitioners, ensuring timely and appropriate care for affected children.