Colors of urine

Q: Pink urine is due to? (select one)

A) phosphate crystals

B) uric acid crystals

Answer: B

For a long time, different colors of urine have excited clinicians (see references). 

The five common colors of urine found in ICU patients are following with potential clues for the underlying pathologies:

1. White: phosphate crystals, chyluria, or propofol.

2. Pink: uric acid crystals or propofol.

3. Green: methylene blue, propofol, amitriptyline, or Pseudomonas aeruginosa infection.

4. Black: hemoglobinuria, myoglobulinuria, melanuria (metastatic melanoma), or alkaptonuria. 

5. Purple: bacteriuria in patients with urinary catheters (purple bag syndrome) co-administration of methylene blue and hydroxycobalamin.

#nephrology

References:

1. Aycock RD, Kass DA. Abnormal urine color. South Med J. 2012 Jan;105(1):43-7. doi: 10.1097/SMJ.0b013e31823c413e. PMID: 22189666.

2. Raymond JR, Yarger WE. Abnormal urine color: differential diagnosis. South Med J. 1988 Jul;81(7):837-41. doi: 10.1097/00007611-198807000-00008. PMID: 3393939.