Urine Appearance

Aka: Urine Appearance, Urine Color, Urine Discoloration, Chromaturia, Dark Urine, Black Urine, Green Urine, Brown Urine, Urine Fluorescence under Woods Lamp

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II. Background

  1. Urochrome (Hemoglobin breakdown product) gives urine its typical yellow appearance

III. Causes: Cloudy Urine

  1. Urinary Tract Infection with increased Urine White Blood Cells (LR+ 3)
  2. Alkaline urine (precipitated phosphate crystals)
  3. High Purine food intake (increased Uric Acid with Hyperuricosuria)
  4. Urine lipids or Chyle (lymph fluid including Fatty Acids)
  5. Urine with high oxalate concentration
  6. Propofol

IV. Causes: Brown or Black Urine

  1. Gross Hematuria with renal source
  2. Bile pigment
  3. Myoglobinuria (e.g. Rhabdomyolysis)
    1. Myoglobin is rapidly filtered by Kidney and discolors the urine red or brown
    2. Myoglobin is not Protein bound (serum is a normal coloration)
  4. Hemolysis
    1. Excretion of Hemoglobin in urine which discolors it red or brown
    2. However, unlike myoglobin, Hemoglobin is Protein bound to Haptoglobin, and also discolors the serum brown
  5. Fava beans (broad beans)
  6. Melanin
  7. Methemoglobinuria
  8. Medications
    1. Levodopa
    2. Metronidazole (Flagyl)
    3. Nitrofurantoin
    4. Antimalarial Medications
    5. Methydopa
    6. Sorbitol
    7. Cascara or senna (bitterbark)
  9. Feces
    1. Enterovesical fistula

V. Causes: Purple Urine

  1. See Brown or Black Urine as above
  2. Purple Urine Bag Syndrome (PUBS)
    1. Rare variant of UTI in catheterized patients with alkaline urine
    2. Depends on phosphatase and sulfatase producing Gram Negative Bacterial strains

VI. Causes: Blue or Green Urine

  1. Urinary Tract Infection due to Pseudomonas
  2. Bilverdin
  3. Medications
    1. Amitriptyline
    2. Cimetidine
    3. Indomethacin
    4. Prochlorperazine (Compazine)
    5. Promethazine (Phenergan)
    6. Propofol
    7. Triamterene
  4. Dyes
    1. Methylene blue
    2. Indigo carmine or indigo blue

VII. Causes: Orange to yellow urine

  1. Increased urine concentration
  2. Bile pigments
  3. Uric Acid (newborns)
  4. Medications
    1. Phenothiazines
    2. Phenazopyridine (Pyridium)
    3. Pyridium
    4. Carrots
    5. Tetracycline
    6. Rifampin
    7. Rhubarb (red in alkaline urine)
    8. Senna (red in alkaline urine)
    9. Sulfasalazine

VIII. Causes: Red Urine

  1. See Red Urine
  2. Gross Hematuria
  3. Pseudohematuria

IX. Causes: Foamy Urine

  1. Dehydration
  2. Significant Proteinuria (e.g. Nephrotic Syndrome)

X. Causes: Urine Fluorescence under Woods Lamp

  1. Fluorescein
    1. Fluorescein is added to antifreeze to aid detection of antifreeze Poisoning
  2. Porphyrins (red)
    1. Increased urine concentrations in Porphyria
    2. Zeligman (1950) Arch Derm Syphilol 61(5): 853-4 [PubMed]
  3. Pteridine
    1. Increased concentrations in Ovarian Cancer
    2. Zvarik (2013) Neoplasma 60(5):533-7 +PMID: 23790172 [PubMed]

XI. References

  1. Hitzeman (2022) Am Fam Physician 106(1): 27-35 [PubMed]
  2. Simerville (2005) Am Fam Physician 71(6): 1153-62 [PubMed]

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