Urobilinogen in Urine

#KYJ - Urobilinogen.

Ward test urine is such a common nursing assessment.

Occasionally I go through some of the urine values seen in abnormal urine tests, but one often poorly understood urine value is urobilinogen.

To understand this substance in urine we need to go back to the origin.

Red blood cells are born in bone marrow, and after 120 days, they are killed off by your immune system.  Components of the dead RBC are recycled, and processed by the liver.

RBC bodies become unconjugated bilirubin, which is processed into bilirubin and further into Bile. There,  bile is secreted to the Gall bladder to be concentrated and stored, waiting for your next fatty meal.

Once fat in your meal is detected by your gut, bile is secreted into your duodenum to mix with food, assisting lipase enzymes to break the fat down into triglycerides for absorption.

The reminant bile passes with undigested food into the large bowel and is acted on by intestinal flora .

This bile is converted into stercobilin, a dark brown pigment that gives faeces it’s colour, and urobilinogen a water soluble waste that is reabsorbed from the faeces.

Now stay with me:

All gut reabsorption of urobilinogen passes into your liver where it is converted into urobilin, and released into the blood stream so the kidneys can excrete it.

It is a light yellow colour and gives the urine it’s hue.  The more urobilinogen and subsequent urobilin you have the yellower your pee.

So it’s in there and it’s normal.

But...

There is a limit! If urobilin on dip stick is reactive (too high) it can represent one of two things.

More bilirubin than the liver can metabolise or hepatic failure.

1- RBC destruction

Haemolysis is the break down of RBCs.  In gut bleeds, haematomas or haemolytic anaemia ; even after a blood transfusion (massive), the sheer numbers of RBCs that are being broken down, and producing bilirubin overwhelms the liver’s capacity to convert to bile, so the liver converts it directly to urobilinogen where kidneys excrete what it can.

2- Liver failure. 

In hepatitis, liver disease like cirrhosis or liver Cancer, or any other liver disease; the conversion of bilirubin fails.  It therefore fails to be utilised adequately, and must be renally excreted.

Symptoms to check your patient for, when there is positive urobilinogen in their WTU, include 

Jaundice or skin yellowing 

Itch, or pruritus. 

Yellowing of the sclera.

Pale/ fatty /offensive faeces

Altered Liver Function Tests.

Coagulation issues leading to bleeding/bruising.

It is not too often that we get a chance to review the little physiology tips and pearls .  So our KYJ (#knowingyourjargon) blogs are one small way I contribute to Free open access medical-education. (#FOAM).

Check them all out on our website. WWE.ect4health.com.au