Charles Davis Aug 2:

Stigma It's true that Merriam-Webster defines stigma as (among other things) "a specific diagnostic sign of a disease", but its use in that sense is in practice confined to external marks: skin lesions. Even then it's by no means common.
http://wordnetweb.princeton.edu/perl/webwn?s=stigmata

Here it would be positively bizarre in English.

Chema Nieto Castañón Aug 1:

I would simply say abnormally coloured urine [abnormal urine color] noticed -or something of the like. "Evidence of" is how that "estigmas" should be read here -most probably, as this is quite an unusual expression no matter what.

Hernan Casasbuenas Aug 1:

pigmented urine stains or pigmented urine stigmas Urine can also be pigmented because of:
Dietary causes
• Beets, blackberries, and rhubarb: can give urine a reddish or pink tint.
• Carrots: Can cause urine to appear orange.
• Asparagus: May cause greenish urine and a distinctive odor.

Medications

• Antibiotics: Such as metronidazole and nitrofurantoin can cause dark urine.
• Laxatives: Containing cascara or senna may darken urine.
• Phenazopyridine: Used to relieve urinary pain can cause orange urine.
• Rifampin: Used to treat tuberculosis can turn urine red or orange.
• Amitriptyline and indomethacin: Can cause blue or green urine.

Medical Conditions

• Hematuria: Blood in the urine can cause it to appear red or brown.
• Liver disease: Such as hepatitis or cirrhosis can lead to dark brown urine due to increased bilirubin levels.
• Dehydration: Concentrated urine can appear dark yellow or amber.
• Porphyria: Disorders that can cause dark reddish or brown urine.
• Alkaptonuria: Genetic condition that can cause urine to turn black when exposed to the air
Other Causes
• Vigorous exercise: Can cause reddish urine due to muscle breakdown
• Urinary tract infections (UTIs)