Categories: Nephrology

What Stones are Radiopaque? (seen on KUB)

STONES SEEN ON X-RAY [70-90% of stones]

  • calcium oxalate, calcium phosphate:: 75-85%    
  • struvite (magnesium ammonium phosphate): 15%  [look for elevated urine pH]   

STONES NOT SEEN ON X-RAY [~10% of stones]

  • uric acid: 5-8% [look for low urine pH]
  • cystine: 1%


  1. Saw KC, McAteer JA, Monga AG et-al. Helical CT of urinary calculi: effect of stone composition, stone size, and scan collimation. AJR Am J Roentgenol. 2000;175 (2): 329-32.
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Dr. C Humphreys

Internal Medicine

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