What laboratory finding is commonly associated with renal amyloidosis?

Renal amyloidosis is characterized by the deposition of amyloid proteins in various tissues including the kidneys, which can lead to significant dysfunction. The presence of apple-green birefringence on polarized light microscopy is a hallmark finding used to identify amyloid deposits. This distinctive feature arises when amyloid fibrils, which are misfolded proteins, accumulate and can be visualized under specific lighting conditions after staining with Congo red dye.

When the Congo red-stained sections are viewed under polarized light, the amyloid deposits exhibit this unique apple-green birefringence, which is crucial for confirming a diagnosis of amyloidosis. Other findings, such as elevated serum creatinine, increased uric acid levels, and presence of hematuria, can occur in renal dysfunction but are not specific indicators of amyloidosis itself. These findings can be observed in a variety of renal diseases and are not exclusive to amyloidosis, making the identification of apple-green birefringence a key diagnostic aspect for this condition.