Case Files 8 - Oh My Urine - SOLVED

An elderly bed bound lady in her early 70's, was found to have urine as of such in her CBD bag.

Given that this is the first time the patient developed this condition,
1) What would your differential diagnoses be?

• Purple Urine Bag Syndrome - Although the name suggests more of urine discoloration, most of the time, the catheter and the bag are more markedly stained by the pigment.
• Porphyria - less likely, but still possible

2) What do you think are the risk factors for such condition?

•  Before we identify the risk factors, it is prudent to know how it is formed. Tryptophan in the food gets metabolized in the intestines into indoles. Enterohepatic circulation converts it into indoxyl suplhate which is then detoxified by the liver into indoxyl. These are excreted into the urine, which would be metabolized by colonizing bacteria(in alkaline environment) in the CBD into indigo (blue) and indirubin (red). The blue and red pigments when mixed, of course, gives you the purple hue from where the name originated from.  

 

•  Risk factors, of course are bedridden female elderly, alkaline urine, chronic constipation(to allow tryptophan metabolism and enterohepatic circulation metabolism to occur), long standing indwelling catheter(for colonization of bacteria in the CBD).

3) How do you treat this condition, should there be a need?

•  There are many advocates for different treatment, including:
  i) Urinary sanitization - by replacing the indwelling urine catheter and ensuring proper catheter hygiene, the urine condition will slowly but surely to improve
  ii) Constipation management - Since constipation is a risk factor, it is prudent to help the patients to move their bowels, hence preventing or reducing the formation of indoxyl.
  iii) A short course of antibiotics - Treatment of the UTI can be done, although it should not be the sole treatment. The above mentioned methods should also be practiced, otherwise there would still be recurrent infection!