Urine discoloration usually results from a benign cause, but is sometimes due to a serious underlying pathology.  Here are some quick tips for evaluation of this common complaint.

Your pee is what color?!?

As most people know, normal urine is a shade of yellow, which ranges from a light to golden tint.  The yellowish color occurs due to the presence of urochrome (a byproduct of bilirubin break-down) This color is variable, and is usually dependent on the patient’s hydration status.  Seeing urine outside of these typical parameters can be very alarming to a patient or caregiver, even though there is usually a harmless cause.

Evaluation of Complaints of Urine Discoloration

In the days of olde, it was common practice for a physician to taste the urine of a patient, in order to develop a diagnosis.  Fortunately, we now have laboratories capable of identifying the components of a patient’s urine.  Prior to laboratory analysis, however, a thorough patient history may reveal the cause of the oddly tinged urine.

What have they eaten (or had to drink) lately?

A good place to start when evaluating discolored urine is with what the patient has had to eat and drink recently.  Foods such as beets and carrots are commonly associated with changing the color of urine to (drumroll)…you guessed it! red and orange.  Many other foods have been implicated, particularly when the patient has consumed a large amount of that particular food.  It is also worthwhile to consider dyes that are present in many processed foods.  Many  popular “energy drinks” contain large amounts of riboflavin (vitamin B2), which can turn the urine a bright orange color.  The (naturally occurring) artificial sweetener, sorbitol has even been known to cause black urine.

Are they taking any new medications?

In most cases, abnormal urine color is the result of medication use.  There are many medications that can cause discoloration, but here are a few of the more common offenders:

• Rifampin (Antibiotic, TB Tx)
• Isoniazid (Antibiotic, TB Tx)
• Phenazopyridine (Analgesic, Tx of UTI Sx)
• Riboflavin (Vitamin B2)
• Sulfasalazine (Anti-inflammatory)
• Warfarin (Anticoagulant)
• Chlorpromazine (Anti-psychotic, many uses)
• Nitrofurantoin (Antibiotic)
• Metronidazole (Antibiotic)
• Senna (Laxative)
• Promethazine (Anti-emetic, many uses)
• Cimetidine (Hismamine blocker)
• Amitriptyline (TCA)
• Metoclopramide (GI stimulant)
• Indomethacin (NSAID)
• Propofol (Gen. Anesthetic)

Medical Conditions Which May Cause Urine Discoloration

If you have weeded through the various foods, drinks and medications that could be causing your patient’s urine discoloration, it may be time to consider a medical cause.  Here are some of the more common conditions that may be responsible.  Keep in mind that the concentration of the urine will have a direct effect on the color, i.e.  dilute red urine may appear brown when highly concentrated.

Red to Orange

• Hematuria (blood in the urine)
  • Infection
  • Renal Calculi
  • Trauma
  • Fistula
  • Renal Disease
  • Contamination (secondary to menstruation)
• Myoglobinuria (myoglobin in the urine)
  • Rhabdomyolysis (often tea colored)
• Porphyria (abnormal heme production)

Brown

• Clot sediment
• Myoglobinuria
• Hemoglobinuria
• Renal disease
• Liver Failure (with concomitant jaundice)
• Melanoma

Purple

• Infection
  • *Seen in catheter bag

Green

• Infection

White (Albinuria)

• Usually due to sediment
  • Calcium
  • Phosphate
• Infection
  • Fungal
  • Bacterial
• Lymphatic Drainage (Chyluria)

“Cloudy Urine”

• WBCs (Pyuria)
  • Infection
  • Inflammation
• Protein (Proteinuria)
  • *Proteinuria will often cause urine to have a persistent “froth” that occurs upon contact with water in the toilet.  A little, non-persistent froth is okay, if it occurs consistently, proteinuria may be the cause.

 

As you can see, there is no “sure bet” diagnosis based on urine color alone, but it may help you guide your differentials.  As for the title, I didn’t lie.  There is a possibility of seeing “rainbow colored urine” in a patient with porphyria.  When the patient with porphyria urinates, the urine may initially be red, but when exposed to sunlight it can change to purple or brown.  I know that this isn’t exactly a rainbow, but it’s still pretty cool right?

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-Owen

 

References

Gill B. Discoloration, Urine . Discoloration, Urine: Urine Discoloration. [accessed 2017 Jan 31]. http://emedicine.medscape.com/article/2172371-overview

Lee J. Purple Urine — NEJM. New England Journal of Medicine. [accessed 2017 Jan 31]. http://www.nejm.org/doi/full/10.1056/NEJMicm061573

Meng QH, Handy B, Wagar EA. It’s Not Easy Being Blue-Green. Annals of Laboratory Medicine. 2013 Nov [accessed 2017 Jan 31]. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3819447/