Acute Post Streptococcal Glomerulonephritis

Acute post streptococcal glomerulonephritis is an immunologic response of the kidney to infection, characterized by the sudden appearance of edema, hematuria, proteinuria and hypertension . It is essentially a disease of childhood that accounts for approximately 90% of renal disorders in children.

Causative organism

Group A beta hemolytic Streptococcus ( Strains M1, M4, M12)

Pathogeneses

Molecular Mimicry– Antibodies against streptococcal antigens react with normal glomerular antigens leading to immune complex formation & complement activation. Release of leukocyte, macrophage, cytokines further increases injury.

Clinical Features

Age- School age children , uncommon below 3 years
Gender- More common in boys
Subclinical episodes are more common than overt disease especially during epidemics
Onset is rapid with puffiness around eyes and pedal edema.
Cola colored wine lasts for few hours to few days.
Hypertension – Patients should be monitored for symptoms of encephalopathy like blurred vision, headache, seizures etc.
Acute phase resolves in 6-8 weeks

Pathology

Light Microscopy– Enlarged and ischemic glomeruli, capillary loops narrowed with mesangial cell proliferation and neutrophil infiltration.

Immunofluorescence– Granular deposits of lgG and complement along capillary wall ( ‘Lumpy-Bumpy’ deposits ).

Election Microscopy– Deposits (humps) on sub epithelial side of glomerular basement membrane & in mesangium.

Laboratory Findings

Urine Analysis– Dysmorphic RBC, Polymorphonuclear leukocytes, RBC cast, Proteinuria 1-2 +
Increased Blood urea and creatinine
Hyponatremia, Hyperkalemia, Metabolic acidosis
Normocytic anemia, Raised ESR, Low grade hemolysis
Low (3 levels which normalizes by 8-12 weeks
Evidence of prior streptococcal infection– ↑ASO titers ( 80% ) or anti-DNase B (skin infection )
Chest X-ray – Prominent bronchovascular marking indicating hypervolemia

Treatment

Mild oliguria with normal BP can be managed at home
Diet–
- Sodium, potassium and fluid restriction till blood levels of creatine reduce and wine output increases.
- Prevent overhydration as it can precipitate left ventricular failure
Diuretics–
- Modest edema = Oral frusemide ( 1-3mg/ kg)
- Pulmonary edema-IV frusemide (2-4 mg/kg)
Daily weight and wine output monitoring
Hypertension –
- Mild – Fluid and salt restriction
- Antihypertensive include Amlodipine, Nifedipine
- Hypertensive emergency – IV Nitroprusside & Labetalol
Left Ventricular Failure – Control Hypertension and induce diuresis by IV frusemide. If no diuresis noted start dialysis
Dialysis–
- Severe renal failure
- Prolonged oliguria
- Fluid overload
- Life threatening electrolyte disturbance
Penicillin given if active pharyngitis or pyoderma is present