Absite Smackdown! · Episode 46: Turkey, Tryptophan, & Carcinoid Syndrome


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Jessica: Hi guys. Welcome back. It's me, Jessica, your host of Absite Smackdown!  And thanks for coming to our Thanksgiving special with me and Dr. David Kashmer. Hi David.
Dr. Kashmer: Happy Thanksgiving, Jessica.
Jessica: Well, I am excited to be doing this cause I have a lot of thoughts. I was reading in our book trying to find something that was Thanksgiving themed and I came across tryptophan and it reminded me of why we get so sleepy when we eat our turkey dinners.
Dr. Kashmer: Yeah, for sure. Tryptophan is an essential amino acid, as you probably know, from what you just looked at. And one thing that's talked about year after year is how turkey makes you sleepy. Well, in fact, just eating can often make you sleepy. We call it being post-prandial and we lived through it in medical school. Each of us that lecture after lunch or that lecture after a lunch conference, blood is shunted to your gut. So whether you had tryptophan or not a big meal will make you tired, but for sure.  There's a lot of thought that tryptophan that amino acid makes you sleepy, especially sleepy with some great turkey at Thanksgiving.
Jessica: So that's not and amino acid we make naturally right?  We have to get that from food correct?
Dr. Kashmer: That's right. That's one of the essential amino acids.
Jessica: Okay. And so turkey is obviously the main one that people know about, but, isn't there an issue with the tryptophan and our serotonin?
Dr. Kashmer: Yeah, it's really interesting. You brought that up and that's a great segue to why this fits in the Absite Smackdown podcast.  Just like the book says tryptophan is a major feature in some of the test questions and things that come up all the time related to carcinoid. There's a lot of facts around carcinoid where that we talked about and tryptophan plays prominently in some of those. So first what's carcinoid. So carcinoid is a tumor that often occurs in the GI tract. There are three main places. The appendix, ileum and rectum are the three most common sites of carcinoid and that spells “air”. So it's important to know that carcinoid can occur in different places, but it turns out that carcinoid is often found incidentally during appendectomy.  As patients get older, in their sixties or so, there's a second peak of appendicitis.
Dr. Kashmer: And those patients present atypically. We call it atypical appendicitis in that age group, even though really that is normal for how it presents in their age group. So we call it atypical but it’s really not. But for older people, when they get appendicitis, they often don't have classic symptoms. They often don't have classic lower quadrant abdominal pain et cetera. And I bring that up because tumors become much more likely to be the cause of appendicitis in those patients to get that obstruction of the appendiceal lumen and then appendicitis. It actually goes from being very low on the list like it does from 20 year olds who have appendicitis to like number two on the list. And one of those tumors is the carcinoid tumor and the carcinoid tumor affects tryptophan. There we go long way to go to get there, but tryptophan gets diverted and the production of 5-HIAA and serotonin is affected.  And that tryptophan diversion to make more serotonin causes problems that ultimately can lead to pellagra because of that diversion of niacin associated with tryptophan. So pellagra is a classic disease that has four D’s:  diarrhea, dermatitis, dementia, and death. And those are some of the indirect ways that tryptophan and carcinoid can come up on the Absite. Again, older patient appendicitis, the cause of the appendicitis may be carcinoid or some other tumor. And, it's just really fascinating how it kind of all links together.
Jessica: I think I remember when I was doing our Daily.Absite.Fact for Instragram, I'm talking about this one time and there was something about what it's like with the cecum when it…where you dissect after…would you explain it once?
Dr. Kashmer: Ok.  What do you do when you're doing an appendectomy and you're taking out the appendix and you say, this doesn't quite look right.  Well, again, you keep in mind, especially if you have an older patient that this may be a tumor, but at the time you take it out, you may not even know that this is a tumor causing this condition.
Jessica: Many carcinoids don’t give a lot of symptoms, right?
Dr. Kashmer: Well, they, they usually don't.  Most commonly they’re asymptomatic and that's another set of facts that come up and we'll even talk about.  I'll tell you first that, the a carcinoid can be in many locations along the appendix.  It can be at the body or tip of the appendix and you take it out, the appendix, then you're done. And if it’s in one of those locations and is less than a two centimeter lesion you're done. If you just take out the appendix and it's in the body or tail. But more importantly, position really is more important than the size of the carcinoid. If there's a lesion and involves the base of the appendix on the cecum you do the right hemicollectomy, and you have to take out the lymphatic drainage with it to get a bunch of nodes to see if the carcinoid is in those nodes. So the first thing is position of the carcinoid.
Dr. Kashmer: Hemicolectomy is the classic standard answer in that situation.  So that's really important. And then to bring up what you said, you know, you kind of asked, “Well, don't most patients not have symptoms?” Yes. Typically carcinoid when it does cause symptoms it causes ones like flushing, diarrhea…these hyper-serotonin symptoms.  But it turns out most people who just have this small lesion do not have any of those symptoms because the drainage goes through the portal vein to the liver and the liver detoxifies everything. So the only way you get symptoms from the carcinoid, including right heart disease with this valvular involvement of the mitral valve, flushing, all these different things is if the lesion has metastasized to the liver.  And then guess what, even those who have metastasis only about 10% or so…most, in other words, do NOT have symptoms from that and only about 10% of those with metastases have symptoms of carcinoid.  So again even if they have mets to the liver, most do not have symptoms.
Dr. Kashmer: So there's a huge fact pattern that gets asked on the Absite all the time.
Jessica: Lots of good Absite questions then. Thanks for covering it Dr. David.
Dr. Kashmer: And you know, it all comes from this tryptophan association with pellagra and carcinoid.  And turkey! It’s kind of worth talking about these things all at once.
Jessica: Well, great. Now I'm just going to associate the 4 D’s with Thanksgiving. That's in my head now. Great.
Dr. Kashmer: I just associate Thanksgiving with cranberry sauce…the kind from the jar that kind of still looks like the jar, or the can, you know?  When you take it out it still has the shape of the can on it.  That's my favorite. You can have the, you can have the carcinoid. That's fine.
Jessica: You really want the jelly kind. Huh yeah.
Dr. Kashmer: I'm sure it's terrible for you. There's probably not a real cranberry anywhere near it, nor has there ever been a real cranberry in here, but it's delicious. I have to have it.
Jessica: I think it's just made from the juice kind of like how, you know, strawberry jam is made from the fruit, but then the jelly is made from the juice. I think it's the same that way. As long as you like it.
Dr. Kashmer: Yeah, I don't question it. I just…it's just delicious. So anyway, there you go. So that's kind of the fact pattern around carcinoid. It's pretty uncommon. It can be a cause of pathologic appendicitis that involves a base of the appendix and the cecum. You take out that right colon, along with the lymphatic drainage, when you see that involvement.  Most commonly no symptoms are present and when you do get symptoms or what we talked about, flushing, diarrhea.  Even if it's metastatic, which is not common, you usually don't get symptoms. And I should mention Octreotide is used to treat the symptoms of carcinoid syndrome if you do see those.
Jessica: All right. So this Thanksgiving, when we're all sitting around and we're tired and we're full and we have that sleepy Turkiness…we can remember these Absite facts.
Dr. Kashmer: So you have a happy Thanksgiving. I'm sure that I'll see you after for another episode.  But until then, hopefully it's a great Turkey day.
Jessica: Yeah. All right. Have a happy Thanksgiving and don't forget…#AbsiteSmackdown!

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