A 108 y.o. woman presents with an indwelling foley and hematuria
What needs to be considered?
Our patient had purple urine bag syndrome. It is signified by purple discoloration of the urine and is seen in patients with long term indwelling urinary catheters. It is due to the presence of indigo and indirubin pigments which precipitate with synthetic materials in the catheter and bag. It is facilitated by urinary tract infections.
The source of the color is tryptophan. It is metabolized in the gut by bacteria and produces indole that is absorbed into portal circulation. And converted into indoxyl sulphate in the liver. This is excreted into the urine without changing its color. Indoxyl sulfate is broken down by indoxyl suphatase produced by some bacteria causing color changes. Indoxyl turns into indigo(blue) and indirubin turns into a red pigment in alkaline urines. The two colors together form purple. The bacterial species most likely to be found are Providencia, Klebsiella, E coli and Pseudomonas. Constipation increases the breakdown of tryptophan in the gut and diets high in tryptophan predisposed to the condition. Alkaline pH in the urine makes the process more likely as does a high tryptophan diet.
FUN FACT –Whole mild, canned tuna, cheese and chocolate are high in tryptophan.
beeturia
DIFFERENTIAL FOR PURPLE URINE
Don’t forget beeturia . 10-14% of the population develop reddish- purple urine after eating beets. This is more common in those who are iron deficient or those who co-ingest spinach or rhubarb. These increase the absorption of the betacyanin alkaloid.
Acute intermittent porphyria-Can also present with urine that darkens to reddish brown on standing. AIP attacks are often linked to menstrual cycles and can be associated with abdominal pain and neurologic symptoms like seizures or psychiatric problems. This is an autosomal dominant inborn error of metabolism which may is found periodically in adult patients. There is a deficiency of porphobiliogen deaminase leading to an accumulation of porphobilinogen and aminolevulinic acid. These compounds are colorless but breakdown into porphyrins which produce the dark reddish color on standing.
Treatment for cyanide poisoning causes purple urine- When patients have elevated lactate after being exposed to a housefire they should be treated for cyanide poisoning since burning paper,cotton and plastics may produce hydrogen cyanide. Hydroxocobalamin combines with cyanide to produce cyanocobalamin(B12) which restores mitochondrial function. The hydroxocobalamin itself imparts a reddish color to the skin and urine.
Our patient had a pH of 8.0 in the urine, no blood, and grew out 50,000-1000,000 colonies of Citrobacter freundii and Enterococcus fecaelis. She was treated with Keflex initially and when sensitivities returned switched to Macrobid. She had purple urine bag syndrome.
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