MadSci Network: Medicine

Re: Why do some people have black urine?

Date: Wed Feb 23 07:17:52 2000
Posted By: BOTFIELD Nigel, Staff, Haematology, Scunthorpe General Hospital
Area of science: Medicine
ID: 949498206.Me

Hi Duffy,
There are a few reasons for black urine 
1)	A build-up of haemoglobin ( Hb for short ) products in the urine
      2)  Colourings such as food dyes or drugs in the urine.

Haemoglobin products have 2 sources - in the first the components of  Hb 
are not put together properly because of an enzyme deficiency, this 
condition is called porphyria and it is a genetic disease. There are 8 
enzymes in the chemical pathway that builds Hb and so there are 8 
different kinds of porphyria. There are a wide range of clinical symptoms 
associated with porphyria one of which is dark coloured urine. Other 
symptoms include mental illness if the Hb products collect in the brain 
and interfere with normal brain activity - a famous sufferer of this 
condition was King George III who ruled England in the late 1700s and 
early 1800s. If the Hb products collect in the skin they can be broken 
down in sunlight to form reactive chemicals which attack the skin and 
leave the skin very sensitive to some chemicals such as the oils in 
garlic - this condition is thought to be the source of some vampire 
legends as the sufferers would avoid the sun and garlic. A good website 
explaining some forms of porphyria can be found at
If you get onto any web search engine and enter porphyria as the keyword 
you will find a large selection of sites dealing with the subject, some 
will be of a technical nature such as the one above and others will be 
personal sites by sufferers sharing their experiences.
The other source of Hb products is the destruction of red blood cells 
(RBCs for short) which is called haemolysis. Once the Hb is released from 
the RBCs it starts to form breakdown products, one of which is bilirubin - 
this causes the yellow discolouration of skin, eyes, plasma and urine in 
jaundice. The more breakdown products present in the urine the darker the 
discolouration from bright yellow through orange to dark brown / black. If 
the kidneys are damaged by the disease process causing the haemolysis or 
if there is surgery affecting the kidneys, bladder or connected organs 
then intact RBCs can pass into the urine adding to the discolouration of 
the urine.
There are many causes of haemolysis -
Bacterial infections such as meningitis may release toxins that destroy 
Viral infections such as dengue fever or yellow fever.
Parasite infections such as Plasmodium falciparum ( a species of malaria ) 
causes black water fever.
Information on these diseases can be found at
Mechanical damage to RBCs caused by long periods of marching or running 
called 'march haematuria' or prolonged bare hand playing of bongo drums.
RBC antibodies may attack RBCs in circumstances such as an incompatible 
transfusion. A person is transfused with RBCs that carry a cell marker ( 
antigen ) that the immune system recognises as foreign to that person and 
so the immune response destroys the transfused RBCs.
Some drugs cause haemolysis by causing a build up of toxic by-products 
that the body cannot remove because of an enzyme deficiency such as 
Glucose -6- Phosphate Dehydrogenase deficiency during treatment with 
Quinine - an antimalarial drug.
Genetic disorders such as sickle cell anaemia and thalassaemia cause 
There are many other causes of haemolysis and a search of the internet 
using the keywords of haemolysis +drugs / antibodies / infections etc 
should yield a lot of information, but remember to use a second keyword as 
searching for haemolysis alone will turn up several thousand sites.
As for the second cause of urine discolouration - food dyes etc, these are 
usually harmless reactions which go once the source of the dye is removed 
from the diet.
A website covering all kinds of causes of urine discolouration can be 
found at
Hope this helps.

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