MadSci Network: Medicine


Date: Mon Mar 21 08:07:20 2005
Posted By: Peter e. Hughes, Faculty, Dept of Biochemistry, Mount Ida College
Area of science: Medicine
ID: 1111092491.Me


This interesting question is a bit complicated and depends on the type of 
kidney trouble.  Some kidney trouble may be minor and short lived, other 
renal troubles may be a bit more tenacious.  

For the sake of our understanding, let’s start with a normal urinary color 
profile and progress through to the possible disease states that may have 
a role in black urine excretion.

The normal color of urine is primarily from the pigment, urochrome.  Urine 
color ranges from a very light yellow to dark amber, depending on the 
dilution of urine.  Dilution is dependent on the amount of water excreted 
and is related to the amount consumed.  

Urine may turn several different colors, Pink, Red, Orange, Blue and 
Brown/Black.  Each of these colors may be caused by a number of different 

Any deviation in the color of a patient’s normal urine requires a visit to 
a physician. Usually a careful patient history,  simple dipstick test, a 
bacteriological smear or urinalysis of a clean catch urine sample will 
rule out most etiologies of colored urines.

The patient usually presents to the clinic as fearful and anxious 
concerning the unusual coloring of their urine.  Upon calming,  the 
patient reports other history:  trauma(bull-riding?), urinary urgency, 
frequency, burning pain with urination(infection?), or colicky, sharp, 
stabbing pains(stones?), as well as any food colorings, over-the-counter 
or prescription medications, or diagnostic dyes recently ingested.  
Posture and circumstances of visualizing the urine may implicate 
contamination, for example, antiseptic(povidone/iodine) or douche 

A controlled ingestion study, full pelvic examination and catheterized 
urine specimen is often necessary to rule out contamination and toxic 
effects issues. 

Brown or black urine which is not due to muscle and blood tissue damage 
may be caused by ingestion of medications and/or foods or a disease 
state.  There is no general “black color”.  The actual chemical causing 
the black color is a chromogen as the result of the metabolic defect.

Copper, phenacetin,  phenol poisoning or medications that cause excessive 
L-dopa or melanin excretion will cause black urine.. Ingestion of large 
amounts of rhubarb, fava beans, or aloe can cause dark brownish black 
urine.  Many medications(see reference) may cause brown or brown-black 

Black urine may be associated with the following disease states:  
Melanoma may cause melanin and melanogen excretion and will darken 
standing urine.. Alcaptonia, a rare hereditary disease, may cause urine to 
turn dark after being exposed to the air over a period of time. 
Urinary tyrosinosis will also cause urine to be brown-black in color.  
In porphyria cutanea tarda, the urine will appear reddish brown in natural 
light but fluoresces pink under ultraviolet light. 

More urological details and links may be found in the references.

Hope this helps! 

1.) Terris, M.D.;  http://urol


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