Radiographic contrast media may cause a number of changes in the urine. Having a history of recent imaging studies with contrast makes the diagnosis a lot easier.
Changes associated with radiographic contrast media:
(1) cloudy urine with visible precipitate
(2) crystals at an acid pH that are strongly birefringent (see below)
(3) high specific gravity (> 1.035) by refractometer if a high osmolar agent was used
(4) discrepancy in specific gravity readings between reagent strip and refractometer
(5) false positive urine protein test by the sulfosalicylic acid precipitation test
Crystals seen at acid pH may include:
(1) uncolored needles
(2) notched plates resembling cholesterol crystals
Many of the reported changes involve the use of a high-osmolar contrast agent.
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Specialty: Nephrology, Clinical Laboratory