2024-01-17 19:47:20
Has it occurred to you why urine is yellow? You are not alone. The truth is that scientists have been puzzling over this question for more than a century.
In the late 19th century, medical researchers identified urobilin as the chemical compound that gives urine its distinctive color.
But what scientists did not know at the time was how the human body produces urobilin from another compound called “bilirubin,” which is a byproduct that means “waste” resulting from the death of red blood cells.
Now researchers from the US say they have identified the enzyme that produces urobilin, according to The Independent.
The study was conducted by researchers led by University of Maryland professor Brantley Hall, and published in the journal Nature Microbiology (Nature Microbiology).
The discovery of this enzyme, called bilirubin reductase, could help understand how microbes influence harmful conditions such as jaundice, gallstones, and inflammatory bowel disease.
Microbes
“It is remarkable that an everyday biological phenomenon has remained unexplained for so long, and our team is excited to be able to explain it,” Hall said.
Speaking to Healthline, he explained, “Unfortunately, the body’s microbes can be difficult to study.”
But he said recent advances in genetics have allowed scientists to compare the DNA of different microbial strains and identify the gene responsible for bilirubin reductase.
“In short, we have revealed a fundamental aspect of how our gut microbes influence our daily lives,” Hall said.
Scientists have long known that the amount of urobilin in a person’s blood, and therefore the color of their urine, is a crucial indicator of certain diseases.
For example, jaundice is caused by an increased amount of bilirubin in the body, sometimes because it is not metabolized properly by the liver or other organs.
This new study also found that newborns, who are susceptible to jaundice, and people with inflammatory bowel disease, have lower levels of the enzyme bilirubin reductase, suggesting that its absence may contribute to such diseases.
What is bilirubin?
When red blood cells finish their life cycle in your body, they break down and pass through the bloodstream to the liver for processing. The liver then secretes bilirubin with other wastes into a liquid called bile. Bile leaves your body through your intestines. Bilirubin is the pigment that gives bile its distinctive yellow color, according to… Cleveland Clinic website.
Health care providers often perform bilirubin tests to check the health of the liver. The bilirubin test is one of a comprehensive group of liver function tests that measure various liver products in the blood. If these values are high or low, they may indicate that your liver is suffering in some way. But abnormal bilirubin levels do not always indicate a liver problem. Sometimes it’s somewhere else.
What causes high bilirubin levels?
Bilirubin may build up in your blood if:
- Your body breaks down too many red blood cells too quickly, for example if you have a blood disorder, such as hemolytic anemia, which destroys red blood cells.
- Difficulty in the liver processing its natural load of bilirubin. Your liver may suffer from excess toxins at times, or it may have chronic liver disease that affects its performance.
- Your biliary system does not remove bile efficiently. There may be a blockage in the bile ducts or gallbladder, causing bile to back up and leak into the bloodstream.
What causes low bilirubin levels (hypobilirubinemia)?
Some medications can lower bilirubin levels, including antibiotics, birth control pills, sleeping pills, and seizure medications. Low levels are generally not a cause for concern.
What does bilirubin do in your body?
Bilirubin is a waste product of dead red blood cells that your body normally expels through the intestines. However, on its way out, it may provide some benefits.
Current studies suggest that bilirubin may act as an antioxidant that helps protect against cardiovascular disease. However, too much can be toxic. If it builds up in your blood, it can make you feel sick. It can also irritate the nerves under the skin, causing itching.
Symptoms of high bilirubin
High bilirubin leads to jaundice, a yellow coating on your skin and the whites of your eyes. Jaundice is often the first symptom that prompts a healthcare provider to check your bilirubin levels. High bilirubin in the blood can also leak into the urine, making it darker. If bilirubin is not excreted in your stool as it should, your stool may be lighter or clay-colored. Very high bilirubin can cause itching.
Bilirubin blood test
A bilirubin blood test measures bilirubin levels in the blood. The health care provider draws a small sample of your blood from a vein and sends it to a laboratory for analysis. The laboratory will measure your bilirubin levels to determine if they are within the normal range. High or low bilirubin levels may indicate that part of the process of breaking down and removing old red blood cells is not working properly.
Normal bilirubin level
On average, total bilirubin levels between 0.2 and 1.3 mg/dL are considered normal for children and adults. If your levels are higher, your healthcare provider may want to investigate further to look for the cause. It may indicate a problem that needs attention. But high bilirubin by itself usually does not require treatment.
It’s a little different for newborns. Normal levels for newborns can range between 1.0 and 12.0 mg/dL. Most of the time, hyperbilirubinemia in newborns is to be expected. But health care providers continue to monitor these cases to make sure bilirubin levels do not rise too much or too quickly. This may indicate a more serious condition, and may also be toxic to the newborn.
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