Patient A is admitted for cardiac surgery on January 10. All his pre-op chemistry tests are normal, and he is cleared for surgery. His surgery is sucessful, and post-op blood and urine samples are submitted to check his status. His urine sample immediately drew notice upon arrival to the lab. Upon analysis, the urine showed:
Colour: Bright Green
Clarity: Clear
pH : 5.5
Specific Gravity: 1.015
Leukocytes: Negative
Hemoglobin: Trace
Protein: Negative
Ketones: Negative
Urobilinogen: Negative
Nitrite: Negative
Microscopic analysis confirmed the occasional red blood cell and 6-10 epithelial cells. No bacteria were seen.
The pre-operative urine sample was pulled, and the colour was a normal clear yellow with normal results.
But what was causing the urine to be so oddly coloured? Was it clinically significant? Upon investigation, the ward confirmed sample quality and a list of possible causal drugs were produced. Among those drugs was a short-acting, intravenous sedative-hypnotic agent by the name of Proprofol (Diprivan). Used to induce and maintain anesthesia or sedation, one of the more infrequent side effects (in < 1%) from Proprofol is a production of bright green urine. It is not clinically significant, and the colour change is known to cease once the proprofol is discontinued.
Other more common causes of the colour change are:
- Methylene Blue: (Blue + Yellow = Green): used in treatment of malaria (third world countries due to cost), methemoglobinemia, cyanide poisoning, and cancer. Also a component of an older urinary analgesic.
- Pseudomonas infection: This produces a deeper, forest green colour with a grapey smell.
- Dietary changes: Examples are excess quantities of Clorets or Blue Listerine
- Magnesium Silicate (Doan's pills): A NSAID used for back pain. OTC medication.
- Medical imaging: Some dyes such as biliverdin are used to assist in in vivo scanning.
Medscape has done an article on similiar cases here.
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