As human beings, we have unique characteristics in almost all areas of our lives. We are diverse in our looks and thoughts. One of such differences is our skin color. It can range from white as snow to dark as the night sky, which are all beautiful variations of what humans can showcase. These features are usually dependent on both our genetics and environment and are, in most cases, no reason for worry. However, there are some skin tones that may need to warrant some hesitation. If a person's sclera (white area of the eye) and skin start to show shades of yellow, it may indicate that there's something wrong inside the body. And this condition is called jaundice.
Before we delve in to that term however, we need to understand how the body breakdowns the RBCs (red blood cells) in the blood. The life span of a single RBC is approximately 120 days. When it's at the end of its life, it is broken down into iron, heme and globin inside the organ called a spleen; our focus will be on the heme. The heme is converted into biliverdin which is then converted into bilirubin. This bilirubin then binds to albumin (a protein) and is then transported to the liver where its metabolism continues. Unconjugated bilirubin (basically bilirubin on its own) is water insoluble, hence relatively difficult to excrete out of the body. Hence, inside the liver, it is bonded to a substance called glucuronic acid and forms bilirubin diglucuronide and is now labeled as conjugated bilirubin. It can now be removed from the body either through the stool or urine and gives both their distinct color.
When we come back to the concept of jaundice, it occurs when there is a disruption in any of the steps mentioned above and is characterized by increase in either conjugated or unconjugated bilirubin levels which then give the body a distinct yellow color. Since the liver is the main organ responsible in this process, causes of jaundice can be classified into prehepatic, hepatic and post hepatic. We can briefly examine each.
Prehepatic is broadly classified into two. Hemolytic anemia which is when there is an increased breakdown of RBCs than normal which can either be congenital (something you're born with) or acquired. Another is transport failure that occurs as it moves from the spleen to the liver either due to poor nutrition or excessive protein loss in the case of a major burn. Then we have hepatic causes which can also be classified into two. There is an inhibition of the enzymatic process mentioned above which can also be congenital or acquired, as well as a decrease in the bilirubin excretion from hepatocytes (the functional and structural unit of the liver) which can also be classified into, you've guessed it, congenital and acquired. Last but certainly not least, post hepatic causes can be classified into three. Intrinsic, meaning there is a substance blocking the tube that excretes the conjugated bilirubin from inside the lumen such as gall bladder stones; extrinsic, compression from the outside such as tumors and iatrogenic, injury to the tube caused by various medical procedures.
Now that we better understand the mechanism behind jaundice, it is wise to remember that it is only merely a sign and not a disease in of itself. So, if detected, an array of investigations ought to be done to get to the root cause and provide definite treatment.
References
Brunicardi, F. C., Andersen, D. K., Billiar, T. R., Dunn, D. L., Hunter, J. G., Matthews, J. B., & Pollock, R. E. (2014). Schwartz’s Principles of Surgery, 10th edition. McGraw Hill Professional.
Club, W. (2020, March 27). Yellow Skin (Jaundice): Pictures, symptoms, causes, and diagnosis. Hamro Nepali Health. https://hamronepalihealth.blogspot.com/2020/03/yellow-skin-jaundice-pictures-symptoms.html
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