Fast Five Quiz: Urine Discoloration

Bradley Schwartz, DO


October 22, 2021

Iatrogenic causes are probably the most common reason for blue urine discoloration. The intravenous injection of methylene blue or indigo carmine produces blue urine discoloration. Likewise, ingestion of a sufficient amount of methylene blue, whether isolated or as a component of other medications, home remedies, or supplements, can also create blue discoloration.

Causes of blue urine discoloration can also produce a green urine hue when combined with the yellow color urochrome produces. In addition, consumption of foods and supplements that contain green pigmentation can also provide the same effect. Large amounts of asparagus or black licorice have been noted to cause green urine discoloration. Some medications that have been implicated include promethazine, cimetidine, amitriptyline, metoclopramide, and indomethacin. Finally, drugs that contain phenol can be metabolized in such a manner that green urine discoloration results.

Certain medical conditions can also lead to green urine discoloration. Urinary tract infection with Pseudomonas species has been observed to produce a green hue in urine. Additionally, fistulas into the urinary tract that facilitate the passage of bile into the urine stream permit its green pigment to stain the urine. Metabolic conditions that cause blue urine discoloration, like the other causes mentioned, can also result in urine appearing green.

Review this slideshow on urinary discoloration.


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