Do Elevated Bilirubin Levels Lead to Hemolytic Anemia Complications?
More Programs and Publications Featuring Dr. Kyle Riding
In this program:
Can elevated bilirubin usually lead to hemolytic anemia complications? Medical laboratory scientist Dr. Kyle Riding explains how elevated bilirubin levels commonly occur, measurement levels that become cause for concern, and potential complications of elevated bilirubin.
Transcript
Interviewer:
So, Dr. Riding, what are the implications of persistently elevated bilirubin levels in patients with hemolytic anemias, particularly regarding the risk of complications such as gallstones or bilirubin-induced neurotoxicity?
Dr. Kyle Riding:
So that is a great question, and it's really a hard one to answer. I'm just going to start off by saying it depends. And that's kind of a cop-out, and I know that. But let's start with gallstones. So if we think back to bilirubin metabolism, it's important to remember red cells rupture, that rupturing causes unconjugated bilirubin to be formed, the liver converts it to conjugated bilirubin, and that gets secreted into your bile ducts. Well, here's the thing, if we have a persistent elevation of bilirubin, it is possible, possible, not a guarantee, that the patient is at an increased risk for gallstones. Because, remember, gallstones are going to be formed as part of the bile that gets created and released by your gallbladder. Bilirubin is a major part of that bile. And effectively, when the gallbladder can't get rid of the bile effectively, what starts to happen is the bile and the salts in it start to crystallize, and so the crystallization starts to form into the stones. Now, gallstones can come in a couple of different varieties. There are bile-predominant gallstones, there are more cholesterol-predominant gallstones. So you're at a risk, but I wouldn't say it's a guaranteed risk. It all depends on what's going on.
With the neurotoxicity, we do worry. So you have probably heard of kernicterus in little babies that are born that are jaundice because of their blood type not being compatible with mom's blood type. And so the baby is born with a little bit of a hemolytic anemia. And what can happen is that overproduction of unconjugated bilirubin, in that little infant...well, unconjugated bilirubin, if it gets high enough, it actually is more readily able to get across what we call the blood-brain barrier. Our body was beautifully designed. We know how important our central nervous system is physiologically, and so we build kind of a Fort Knox around our central nervous system that we call the blood-brain barrier. Only certain things are able to get through that barrier. When unconjugated bilirubin gets high enough, it is able to get in and cross that blood-brain barrier and cause neurotoxicity symptoms and encephalopathies and some pretty scary things. That is a major concern, particularly in infants, because of the blood type incompatibilities that can happen. That's why if a baby is born jaundice, we put them under the lamp so that, bilirubin is very light-sensitive. It gets broken down by light quite easily. And so putting the baby under the light breaks down that bilirubin before it can cause damage to their central nervous system.
It can happen in adults, where if the unconjugated bilirubin does get high enough. And we're talking like, typically about 25 times the upper limit of normal. You usually need an unconjugated bilirubin of, a lot of estimates say around 25 mg per dl. The normal is around 1 mg per dl. But typically, if it gets that high, it can start getting into the blood-brain barrier, causing some neurotoxicity. However, that high of a level of an unconjugated bilirubin is rare in adults,..the unconjugated bilirubin is rising because there's some massive hemolytic process that's debilitating the patient before we get to a neurotoxic place because of the bilirubin. Now, we all, of course, can appreciate there are patients out there with hemolytic diseases, like sickle cell disease, that face neurological complications. However, that's usually because of different reasons that are happening. It's not really the unconjugated bilirubin typically doing that, it's other facets of what the sickle cell disease is doing to the red cells and doing to the circulatory system around the brain that leads to those neurological symptoms in those patients.
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