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A 34-year-old homeless alcoholic is brought to the ER with vomiting and prolonged oliguria. After initial evaluation, renal biopsy reveals marked ballooning and vacuolar degeneration of proximal renal tubules: multiple oxalate crystals are observed in the tubular lumen. This patient’s condition is most likely related to which of the following?
A. Prolonged hypotension
B. Advanced liver disease
C. Severe infection
D. Chronic undernutrition
E. Toxic renal injury
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"E" is correct
Ethylene glycol is a widely-available substance found in automobile antifreeze, engine coolants and hydraulic brake fluids. Ethylene glycol is rapidly absorbed from the GI tract and metabolized to glycolic acid, which is toxic to renal tubules, and to oxalic acid, which precipitates as calcium oxalate crystals in the renal tubules.
Symptoms of acute renal failure (oliguria, anorexia, flank pain) are characteristic of ethylene glycol poisoning and occur in 24-72 hours after the ingestion. A high anion-gap metabolic acidosis and osmolar gap are typical.
Calcium oxalate crystals are detected by microscopy of the urine and are shaped like folded envelopes. Although glomeruli appear normal signs of tubular epithelial damage are clearly visible on light microscopy. This damage manifests itself histologically as ballooning and vacuolar degeneration, predominantly in the proximal convoluted tubules is seen on light microscopy.
(Choices A and C) Prolonged hypotension or severe infection can lead to ischemic acute tubular necrosis (ATN). Oliguria, muddy brown casts, and anion gap metabolic acidosis are characteristic. No oxalate crystals are present.
(Choice B) Advanced liver disease with portal hypertension and ascites may lead to the development of renal failure (hepatorenal syndrome). The hallmark of this condition is renal vasoconstriction. Kidneys are histologically normal and resume their function following liver transplantation.
(Choice D) Chronic undernutrition doesn't lead to tubular epithelium damage or to the formation of calcium oxalate crystals.
