Doctors in Kentucky have described a rare case in which an elderly woman’s urine turned deep purple due to a complication of a bladder infection.
The 76-year-old unnamed patient suffering from heart failure, kidney failure and bladder cancer was hospitalized and attached to a catheter to drain her urine.
An infection in her urinary tract caused a biochemical reaction that produced blue and red pigments in her pee that, when oxidized in the catheter bag, turned a dark purple.
Doctors made the rare diagnosis of purple urine bag syndrome (PUBS), which occurs in as many as 42 percent of patients who are connected to catheters for a long time.
A chemical reaction in the liver produces an indigo pigment and indirubin, a red pigment. Those pigments combine and oxidize to turn purple in the urine bag.
Purple urine bag syndrome (PUBS) is usually a complication of urinary tract infections (UTIs), as is the case with this 76-year-old woman, where catheter bags and tubes turn purple. Although almost always benign, the violent shade of purple can be alarming to patients, families and clinicians
Doctors from the University of Pikeville in Kentucky revealed the case in the journal Oxford Medical Case Reports.
In the report, they said: ‘Elderly and bedridden patients with multiple comorbidities are more likely to require long-term indwelling catheters, which increases their risk of urinary tract infections.
“Such patients are more likely to become infected by the rarer bacteria that can cause PUBS.”
The patient had a long history of serious medical problems, including congestive heart failure, chronic kidney disease and bladder cancer.
She went to the hospital because of shortness of breath related to her cardiovascular problems.
To drain her bladder, doctors connected the woman to a catheter and then treated her with IV medication to reduce the swelling associated with congestive heart failure.
After four days in the hospital, the patient’s urine bag turned a violent purple hue.
Dipstick tests showed that her urine was extremely alkaline with a pH of 8.5, a symptom that her kidneys were not working properly.
She also had high levels of the bacteria Proteus mirabilis, a common cause of complicated urinary tract infections.
PUBS was first clinically described in 1978.
The condition is almost always benign, but can be alarming for patients and their loved ones.
In addition to age and frailty, being female and renal failure are also primary risk factors for alkaline urine and constipation.
The phenomenon is the result of a multi-step biological process in the gut.
Bacteria help break down the amino acid tryptophan, which in the gut becomes a compound called indole, where it is then taken to the liver and converted to indoxyl sulfate.
Indoxyl sulfate is metabolized in the urine to indoxyl with the help of bacteria that produce phosphatase and sulfatase.
Indoxyl changes to indigo, the blue color, and indirubin, the red color, in alkaline urine, and these colors then mix to form a purple color.
Purple urine usually signals doctors that the patient has a urinary tract infection, but not always.
Chronic constipation is often associated with an overgrowth of bacteria in the colon, which increases the conversion of tryptophan to indole.
Most people who experience PUBS will be fine, but immunocompromised patients are prone to serious illness, the doctors said. For example, Fournier’s gangrene can develop as a result of a urinary tract disorder. It is a rare, life-threatening bacterial infection in the scrotum (including the testicles), penis, or perineum that causes body tissue to die and die.
The doctors said: ‘Medical treatment of PUBS requires replacing 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 home with recommendations for follow-up with her nephrologist and urologist as an outpatient.’