What is the role of lab tests in the workup of poststreptococcal glomerulonephritis?

Updated: Dec 16, 2020
  • Author: Duvuru Geetha, MD, MRCP; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Answer

Laboratory studies in acute poststreptococcal glomerulonephritis (APSGN) include tests to provide evidence of preceding streptococcal infection, renal function studies, and serologic studies.

Evidence of preceding streptococcal infection can be determined as follows:

  • Antibody titers to extracellular products of streptococci are positive in more than 95% of patients with pharyngitis and 80% of patients with skin infections.

  • The antistreptolysin (ASO), antinicotinamide adenine dinucleotidase (anti-NAD), antihyaluronidase (AHase), and anti–DNAse B are commonly positive after pharyngitis, and anti–DNAse B and AHase titers are more often positive following skin infections

  • ASO titers are frequently used to document streptococcal infection, but a more sensitive test is the streptozyme test, which tests antibodies to ASO, anti–DNAse B, AHase, and anti-NAD

  • Studies suggest that the relatively unavailable antizymogen titer test is superior to both anti–DNAse B and ASO titers

  • Antizymogen titers that are two dilutions higher than the mean in healthy controls are reported to have a sensitivity of 88% and a specificity of 85% in the diagnosis of streptococcal infection in patients with glomerulonephritis

  • High antibody titers to glyceraldehyde phosphate dehydrogenase are also found in persons with APSGN

  • In general, the antibody titers are elevated at 1 week, peak at 1 month, and fall toward preinfection levels after several months


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