First, a poll: Does Ammonia cause hepatic encephalopathy?
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How did NH3 get involved with
#HE in the first place? Step 1: In 1877 Eck develops the first successful vascular anastamosis, a portocaval shunt. https://www.ncbi.nlm.nih.gov/pubmed/9186464 Step2: Pavlov improves it Step3: Dogs get goofy after eating meat:"Meat stupor" Step4: What's up with meat!?pic.twitter.com/XYsb3t2put
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Enter McDermott and this 100% bananas paper from 1954:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1073522/?page=1 …
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Digression: McDermott was awesome: War hero, fixed Muhammad Ali's hernia, revolutionized liver surgery Here is his obit:https://www.nytimes.com/2001/07/25/us/william-v-mcdermott-84-combat-surgeon-and-teacher.html …
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So, McDermott cared for a man with painless jaundice. In the OR: A 5cm pancreatic cancer with superior mesenteric vein involvement. To resect in 1 stage, he smacked the portal vein onto the inferior vena cava- Eck fistula! He pub'd this story in 1952: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1802351/?page=4 …pic.twitter.com/GPDg3M2E04
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Then the patient keeps getting readmitted for bizarre "irrational" behaviour which occasionally progresses to coma Everyone was stumped So they studied him to figure it out. It took 6 months
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They noticed he would get confused after eating meat Could this be "meat stupor"? What's in meat? Amino acids and NH3 containing stuff! To summarize, the highlights: First they fed him urea -->HE (Urea --> Ammonia) So they fed him ammonia -->HE Thus Ammonia -->HE. QEDpic.twitter.com/k59JGhKG4n
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Are you interested in what (specifically) ammonia does in the brain? Lots of bad things Let me send you to a few references: https://www.ncbi.nlm.nih.gov/pubmed/10728803
@JHepatology https://www.ncbi.nlm.nih.gov/pubmed/12668989@HEP_Journalpic.twitter.com/DJjlYj5xOV
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So ammonia causes HE. There, I said it But is it the whole story?
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Time for Jules Stahl and this 25 page single-author paper in
@AnnalsofIM 1963 Turns out, Ammonia levels have nothing to do with grade of HE We knew this in 1963! http://annals.org/aim/article-abstract/678478/studies-blood-ammonia-liver-disease-its-diagnostic-prognostic-therapeutic-significance …pic.twitter.com/K01SXEUWsq
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Still true in 2003! https://www.ncbi.nlm.nih.gov/pubmed/12637132 Low levels usually good but even 1 in 13 people with Grade 4 HE (coma) have stone-cold normal NH3. And an ammonia level of 150 could mean anything from no HE to coma.pic.twitter.com/AhBzvPkmPl
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Somewhere, someone is doing sudoku with an ammonia of 210 just to prove a point
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HE is a clinical diagnosis. NH3 levels just cannot diagnose or grade HE. But why?
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Pts w/cirrhosis & portal htn circulate bacteria from the gut. This causes inflammation Inflammation enhances diffusion of NH3 into the brain (review: https://aasldpubs.onlinelibrary.wiley.com/doi/epdf/10.1002/hep.23367 …) Don't forget: lots of HE is PRECIPITATED by what, u guessed it, infections (inflammation!)pic.twitter.com/uW4AQoEUrh
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Cool study: Shawcross induced hi-NH3 - a la McDermott, by infusing ammonia salts This led to
cog function
Now, Abx
inflammation
Sp they gave Abx which
inflammation
Then they
NH3 ...but there was no cognitive dysfunction!
https://www.journal-of-hepatology.eu/article/S0168-8278(03)00545-2/fulltext …pic.twitter.com/RBHSWb6rEp
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One major reason the levels are useless: We have no way of accounting for the impact (and amount) of inflammation.pic.twitter.com/l3lgMGcWNc
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Act 2: Ammonia is bad and I certainly dont want to cause meat stupor! Should I ask my patient with cirrhosis to eat a low protein diet?
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Although NH3 levels are far from perfect, we definitely want to protect our brains from high NH3 If your liver is not working and the portal HTN is shunting blood We need a second line of defense We have one: It's the muscle!
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Skeletal muscle accounts for >50% of NH3 metabolism in healthy people, even more in patients with cirrhosis. Lockwood followed radiolabelled NH3 to the muscle (JCI 1979;63); Olde-Damink confirmed the role of muscle in many cool studies (e.g. Hepatology. 2002;36:1163)pic.twitter.com/7lQg645S8N
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What happens when NH3 gets to the muscle? NH3 gets converted to glutamine at the price of a branch-chain amino acid (produced from muscle breakdown) NH3 detox by the muscle is a catabolic process!pic.twitter.com/4F1MbhQOLP
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Restricting dietary protein is a great way to exacerbate catabolism and
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That's why patients with HE should have >1 g protein / kilogram body weight. NH3 may rise after a protein-rich meal ... but it is safe RCT: https://www.ncbi.nlm.nih.gov/pubmed/15246205 RCT: https://www.ncbi.nlm.nih.gov/pubmed/18627001 Guideline:https://www.ncbi.nlm.nih.gov/pubmed/16707194
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So the next time you see a patient with cirrhosis are you going to check ammonia level?
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And when you see them, are you going to recommend a low protein diet?
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I hope you enjoyed this. Wanted to thank
@tony_breu for his inspiration. If you are interested in more stuff about ammonia, here's a plug for our paper "Refining the Ammonia Hypothesis" in@MayoProceedings https://www.sciencedirect.com/science/article/pii/S0025619615002177 … with@Vilas_Pat and@ZGordonJiangShow this thread
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