Merck Manual

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Causes Of Urine Color Changes

Causes Of Urine Color Changes

Color

Cause

Red, orange, or brown

Bilirubin

Hemoglobinuria

Drugs (eg, cascara, diphenylhydantoin, levodopa, methyldopa, phenacetin, phenazopyridine, phenindione, phenolphthalein, phenothiazines, rifampin, senna)

Foods (eg, beets)

Free myoglobin

Porphyrins

RBCs

Cloudy white

Precipitated phosphate crystals

Green

Drugs (eg, amitriptyline, methylene blue, propofol)

Pseudomonas infection

Purple (rare)

Gram-negative bacteria in urinary catheters*

Dark brown or black

Melanoma†

* Rarely, urine in collection bags of catheterized, bedbound patients turns purple (purple urine bag syndrome) when urinary gram-negative bacteria metabolize a tryptophan metabolite (indican) in alkaline urine into indigo; this reaction is clinically insignificant.

† Caused by oxidation of excessive homogentisic acid or melanogen when urine is exposed to air for several hours.