Diagnostics

• Urinalysis with microscopy: nephritic sediment

  • Hematuria with RBC casts

  • Proteinuria

  • Pyuria

• Quantification of proteinuria: typically shows non-nephrotic range proteinuria

• BMP may reveal:

  • ↑ BUN, ↑ creatinine

  • Electrolyte abnormalities

• CBC: may show normocytic, normochromic anemia

• C3 complement, C4 complement levels: classically shows ↓ C3 complement with normal C4 complement

• Antistreptococcal antibody titers

  • ↑ ASO, ↑ anti-DNase B antibodies, ↑ antihyaluronidase antibodies

• Isolation of group A beta-hemolytic streptococci

  • Pharyngitis: rapid strep test, throat culture

    1. Skin lesions: wound cultures

PSGN typically occurs following a GAS infection rather than during an active infection. Obtain appropriate diagnostic studies to isolate group A beta-hemolytic streptococci only if active infection is suspected.

• Indications: may be obtained during a diagnostic workup of hematuria

• Findings: typically normal; may show nonspecific increased echogenicity of the renal cortex

• Indications: (not routinely performed)

  • Signs of rapidly progressive glomerulonephritis

  • Atypical presentation

• Supportive findings: proliferative glomerulopathy with immune complex deposits

  • Light microscopy: enlarged and hypercellular glomeruli

  • Immunofluorescent microscopy: granular deposits in the glomerular mesangium and capillaries

    • Consisting of IgG, IgM, C3 complement

    • Lumpy-bumpy appearance (also called a starry sky appearance)

  • Electron microscopy: immune complexes between the epithelial cell layer and the glomerular basement membrane (referred to as subepithelial humps)