Glomerulonephritis, Acute Post-streptococcal, APSGN

Notes

## Basic introduction:

  • It is an inflammatory renal disease that frequently occurs as a late complication of pharyngitis or skin infections due to a nephritogenic strain of β-hemolytic streptococci.
  • It is the major subtype of the Acute Glomerulonephritis (AGN) constituting 80-90% of all AGN cases
  • It is one of the diseases of the acute nephritic syndrome in which inflammation of the glomerulus is characterized by proliferation of cellular elements secondary to an immunologic mechanism.
  • Generally, APSGN has a good prognosis with early detection and treatment. Spontaneous improvement begins within 7 days, edema resolution is within 5-10 days and hypertension resolution is within 2-3 weeks. Microscopic hematuria may remain for many years.

## Pathology of APSGN:

  • There is infection by nephritogenic strain of β-hemolytic streptococci
  • Immune system is elicited and immune complexes are formed
  • There is activation of complement system and recruitment of leukocytes
  • Cytokines and proliferative factors are secreted
  • Glomerular basement membrane (GBM) is damaged
  • This results in hematuria, proteinuria and the presence of RBC casts
  • Cytokines and proliferative factors also stimulate the growth and proliferation of endothelial cells causing the blockage of renal capillaries which in turn leads to oliguria, sodium and water retention as well as hypervolemia, edema, hypertension, heart failure, renal failure and encephalopathy.

## Epidemiology and Statistics:

  • Mortality rate from APSGN –< 0.5% of those who get the disease
  • 8% of the children affected by APSGN develop chronic renal disease (hence it is necessary for these children to be followed up by the nephrologist/urologist)
  • Recovery rate>95%
  • Children tends to recover faster than adults

## Possible complications of APSGN:

  • Nephrotic syndrome (due to the loss of too much protein)
  • Acute kidney failure
  • Chronic glomerulonephritis
  • Encephalopathy
Symptoms
  • It can be asymptomatic and sometimes with microscopic hematuria
  • Abrupt onset of smoky hematuria, proteinuria, edema, and hypertension
  • Edema of the face (with characteristic puffiness of the eyes in the morning)
  • Brown/pink and foaming urine
  • Back pain
  • Headache
  • Visual disturbances
  • Vomiting
  • Convulsions
  • Azotemia
  • Coma
  • Encephalopathy
  • Acute tonsillitis with cervical adenitis
  • Skin sepsis
  • Oliguria followed by diuresis (characteristic oliguric and diuretic phases)
  • Hypertension
Diagnosis
  • Urinalysis
  • Blood urea (normal but it may be elevated in oliguric phase)
  • Throat and/skin swab (for streptococcus)
  • Renal ultrasound
  • Antistreptolysin O titer
  • Renal biopsy (not always)
Differential
  • Hematuria
  • IgA Nephropathy
  • Diffuse Proliferative Glomerulonephritis
  • Endocarditis-associated glomerulonephritis
  • Membranoproliferative Glomerulonephritis
Prevention
  • Prompt treatment of streptococcal infections
Management
  • By the time the patient presents with symptoms, the glomerular injury has already occurred, and the healing process has begun. However, treatment is normally supportive and it targets potential complications
  • Caps Amoxicillin 500mg TID x 10/7
  • In oliguric phase restrict salt and fluid intake and administer furosemide 20- 40mg
  • Monitor weight daily
  • Also treat hypertension if present
  • Bed rest
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