Doctors in Kentucky have detailed a rare case in which an elderly woman’s urine turned deep purple due to a bladder infection complication.
The 76-year-old unnamed patient suffering from heart failure, kidney failure, and bladder cancer was hospitalized and hooked up to a catheter to carry away her urine.
An infection in her urinary tract prompted a biochemical reaction yielding blue and red pigments in her pee that, when oxidized in the catheter bag, turned dark purple.
Doctors issued the rare diagnosis of purple urine bag syndrome (PUBS), which occurs in as many as 42 percent of patients hooked up to catheters for a long time.
A chemical reaction in the liver yields an indigo pigment and indirubin, a red pigment. Those pigments are combined and oxidized to turn purple in the urinary bag.
Purple urine bag syndrome (PUBS) is usually a complication of urinary tract infections (UTIs), as is the case in this 76-year-old woman, where catheter bags and tubing turn purple. While it is almost always benign, the violent shade of purple can be alarming for patients, families, and clinicians
Doctors from the University of Pikeville in Kentucky revealed the case in the journal Oxford Medical Case Reports.
Writing in the report, they said: ‘Elderly and bedridden patients with multiple comorbidities more often require long-term indwelling catheters which increase their risk of UTIs.
‘Such patients are more likely to be infected by the rarer bacteria which can go on to cause PUBS.’
The patient had a long history of severe medical issues, including congestive heart failure, chronic kidney disease and bladder cancer.
She went to the hospital for shortness of breath linked to her cardiovascular issues.
To drain her bladder, doctors connected the woman to a catheter and then treated her with IV medication to reduce swelling linked to congestive heart failure.
After four days in the hospital, the patient’s urinary bag took on a violent purple hue.
Dipstick testing found that her urine was extremely alkaline with a pH of 8.5, a symptom of her kidneys working improperly.
She also had high concentrations of the bacteria Proteus mirabilis, a common cause for complicated urinary tract infections.
PUBS was first described clinically in 1978.
The condition is almost always benign, but it can be alarming to patients and their loved ones.
As well as age and frailty, being female and in kidney failure, having alkaline urine and constipation are also primary risk factors.
The phenomenon is a result of a multi-step biological process in the gut.
Bacteria aids in the breakdown of the amino acid tryptophan, which becomes a compound called indole in the gut, where it is then taken to the liver and turned into indoxyl sulfate.
Indoxyl sulphate is metabolized to indoxyl in the urine with help from bacteria, which produce phosphatase and sulphatase.
Indoxyl turns into indigo, the blue color, and indirubin, the red color, in alkaline urine, and these colors then mix to form a purple color.
Purple urine typically signals to doctors that the patient has a urinary tract infection, though not always.
Chronic constipation is commonly associated with an overgrowth of bacteria in the colon, which increases the conversion of tryptophan into indole.
Most people who experience PUBS will be ok, but immunocompromised patients are susceptible to severe disease, the doctors said. Fournier’s gangrene, for instance, can arise as a result of urinary tract disease. It is a rare, life-threatening bacterial infection in the scrotum (which includes the testicles), penis, or perineum that causes body tissue to die and slough off.
The doctors said: ‘Medical management of PUBS requires changing the catheter and administering appropriate antimicrobial therapy to treat the underlying bacterial infection.
‘Her constipation resolved, and a 5-day course of antibiotics was completed. The patient was discharged to a nursing facility with recommendations to follow up with her nephrologist and urologist as an outpatient.’
WHAT IS PURPLE URINARY BAG SYNDROME?
Doctors say the bluish discolouration of urine is triggered by a series of chemical reactions in the body.
Bacteria responsible for the UTI breakdown metabolites of tryptophan – an amino acid found in food.
This produces indole, which becomes indoxl sulfate, which then oxidises into blue-coloured indigo and the reddish indirubin.
Doctors at the King George’s Medical University in Lucknow, India, wrote in the British Medical Journal Case Reports last year: ‘The combination of indigo and indirubin gives a purple hue to the urine collection bag.’
However, the discolouration is completely benign, and often the underlying UTI is considered more concerning to medics.
Women face a higher risk of developing PUBS because they have a shorter urethra, which leaves them more vulnerable to catching UTIs.
Constipation can also boost the odds because it gives bacteria more time to break down tryptophan metabolites in the body.
It is unclear how common PUBS is, but it has been described as an ‘uncommon phenomenon’.
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