aka Unusual Urine 005
A 76-year-old male nursing home resident with dementia and end-stage renal disease who was undergoing hemodialysis was admitted to the hospital after a syncopal episode that occurred during dialysis.
When a urinary catheter was placed, purple urine was drained. The urinalysis showed a pH of 9.0 and bacteriuria but no hematuria or pyuria
What are potential causes of purple urine?
Unusual Answer
Urine can present in a veritable rainbow of colours…
Purple discoloration can occur in alkaline urine as a result of the degradation of indoxyl sulfate (indican), a metabolite of dietary tryptophan, into indigo (which is blue) and indirubin (which is red)
Bacteria such as Providencia stuartii, Klebsiella pneumoniae, P. aeruginosa, Escherichia coli,and enterococcus species are most commonly implicated
The clinical course is benign, and the urine typically clears with resolution of the bacteriuria and acidification of the urine.
References
- Lee, J. Purple Urine N Engl J Med 2007; 357
