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[[{"type":"media","view_mode":"media_crop","fid":"48539","attributes":{"alt":"","class":"media-image media-image-right","height":"269","id":"media_crop_5145982228357","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"5796","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"float: right;","title":"EMresource.ORG","typeof":"foaf:Image","width":"359"}}]]A bedridden elderly female with a history of dementia, Parkinson disease, and a chronic indwelling Foley catheter is brought to the emergency department for evaluation of purple urine noted in her Foley bag. The patient denies any fever, vomiting, or weakness, but her lower abdomen is “uncomfortable.” She does not recall eating beets, blueberries, or anything purple recently.
Vital signs are normal. Physical examination finds a conversant elderly woman in no acute distress. Head and neck exam is unremarkable with a moist oropharynx. Lungs are clear and the heart is regular. There is no abdominal or flank tenderness and no peripheral edema.
What testing should be performed?What is the most likely cause for these findings?
Answer
Urinalysis and culture should be ordered. Purple urine is most commonly caused by UTI from certain Klebsiella or Pseudomonas species that break down tryptophan into indole which then interacts with the plastic of the catheter bag producing a purple coating. In this case the cultured organism was Klebsiella.
Discussion
Urine discoloration has many causes, from common foods like beets to rare diseases like porphyria, which literally translates to “purple urine.” Foods that can discolor urine when ingested in excess other than beets include blackberries, fava beans, carrots, and rhubarb (see “Red” and “Orange” in the Table below). Many medications can discolor urine, some of the most common being pyridium, rifampin, iron, nitrofurantoin, sulfa, and metronidazole (see Table). Medical conditions that can affect urine color include dehydration, porphyria, melanoma, rhabdomyolysis, liver disease and, UTI.
Brown: | Porphyria, melanoma, rhabdomyolysis, bile, cascara, iron, macrobid |
Red: | Blood, beets, food coloring, myoglobin, urate, blackberries, dyes, serratia, fava |
Meds: | Cascara, chloroquine, Deferox, doxorubicin, Flagyl, ibuprofen, iron, Macrobid |
Orange: | Pyridium, rifampin, bile, carrots, rhubarb, sulfa, fluorescein, vit A, vit B12 |
Green/Blue: | Biliverdin, Elavil, food color, methylene blue, pseudomonas, Robaxin, Tagamet, blue diaper syndrome (tryptophan), triamterene, Doan’s kidney pills, propofol |
Purple: | Alkali urine with |
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