There have been a lot of posts about blood work and knowing your liver,
I thought I would post some information that I have as a nurse working with patients that are being evaluated for liver transplant.
The only way to know what the damage is to a liver is to biopsy it, but that is a dangerous test that should not be undertaken lightly, so is not available to many of us.
Next is an ultrasound or CT scan - but these are not always reliable...
This a collection of information about results in bloodwork...
As with all medical information - there is always contraindicatory information, so I am just sharing what I have...it is likely much more relaiable than wiki....
The transaminases (AST/ALT) are not really "liver function tests" despite what everyone says all across medicine. It is a misnomer. If you want to know how someone's liver is functioning, use the coags (INR), bilirubin, and albumin (it is made by the liver). . Many pts on the liver tx list will have totally out of whack INR, bili, albumin...but their transaminases will be normal. This is especially true because the shrunken cirrhotic livers have fewer hepatocytes to become damaged (see below).
The transaminases are enzymes that live in hepatocytes, and if the hepatocytes are injured and break down, they will be released into the bloodstream. Again, they aren't "LFT's" despite being labeled that all the time.
The ALT (alanine transaminase) is more specific to hepatocytes (remember aLt= Liver) whereas the AST is found in more places.
Bilirubin is a function of hemolysis, hematoma, metabolic diseases, and biliary tract obstruction?.among other things. If the bili is moderately high- 1.5 to 3 or so?and it means nothing especially if they are a trauma or hemorrhagic stroke victim who has bled and is being transfused or undergoing normal erythropoiesis in response to blood loss. It would help know a "direct" (from the liver) versus "indirect" bilirubin? If the high bilirubin is "indirect" in nature-- it has very little or nothing to do with the liver.
The transaminases can tell us more meaningful information. A hallmark of alcoholic liver disease is an AST:ALT ratio of 2:1 or greater. In fact, life insurance companies use this to screen people and raise premiums. In viral hepatitis, both will usually be elevated at closer to the 1:1 ratio?.or the ALT even higher than the AST. The elevation is not usually very marked- one study found that the "mean" ALT of a group of people with HepC was 104. Of course, none of this is pathognomonic- and mildly elevated transaminases are also seen in NASH and drug related hepatitis.
We can get other info from the Alk Phos and GGT. Alk phos is nonspecific as it is seen in the bone, kidney, liver, leukocytes, etc. If it is high, a GGT can be added to see if it is likely liver in origin (GGT also high). GGT is also often high in alcoholic liver disease.
When you see someone otherwise young and healthy with SKY HIGH transaminases (like in the 700+ range)?.this is suggestive of a severe acute hepatic injury. Tylenol was a likely culprit (there are other drugs that do the same thing but Tylenol is common) given the suspicion in that case for drug overdose.
In general, the AST and ALT aren't actually "function" tests (albumin, bilirubin, and INR are!). AST and ALT are two enzymes that "live" in hepatocytes. When the hepatocytes are damaged, and rupture/die/undergo apoptosis/necrose/damage, they release AST and ALT into the bloodstream.
It certainly helps when the AST/ALT are "trending down" because this means the damage to the liver is not "ongoing" and has slowed or stopped. If they keep rising, it is not good at all- as we already know.
Sometimes, all of the hepatocytes are SO injured and leak all of their AST and ALT, that there are no cells left to "be injured". The transaminases start "coming down"...but the injury has happened. Livers can "regenerate" but it takes weeks to months for it to start.
In the cirrhotics, you'll notice they usually have "normal transaminases". yet their livers don't function at all. This is why transaminases aren't really "liver function tests". The cirrhotics will have horrific bilirubin, INR, albumins, but normal AST/ALT. Their livers are so damaged and burnt out from the years of damage, that they can't even spill AST/ALT much anymore. There isn't anything left to damage. The hepatitis patients will have chronically high AST/ALT, usually in the 100-200 range, because of ongoing viral liver damage happening every day.
The "shock liver" patients (MSOF, tylenol, ischemia, etc) will have these sky high AST/ALT that indicate a much more severe issue.
I thought I would post some information that I have as a nurse working with patients that are being evaluated for liver transplant.
The only way to know what the damage is to a liver is to biopsy it, but that is a dangerous test that should not be undertaken lightly, so is not available to many of us.
Next is an ultrasound or CT scan - but these are not always reliable...
This a collection of information about results in bloodwork...
As with all medical information - there is always contraindicatory information, so I am just sharing what I have...it is likely much more relaiable than wiki....
The transaminases (AST/ALT) are not really "liver function tests" despite what everyone says all across medicine. It is a misnomer. If you want to know how someone's liver is functioning, use the coags (INR), bilirubin, and albumin (it is made by the liver). . Many pts on the liver tx list will have totally out of whack INR, bili, albumin...but their transaminases will be normal. This is especially true because the shrunken cirrhotic livers have fewer hepatocytes to become damaged (see below).
The transaminases are enzymes that live in hepatocytes, and if the hepatocytes are injured and break down, they will be released into the bloodstream. Again, they aren't "LFT's" despite being labeled that all the time.
The ALT (alanine transaminase) is more specific to hepatocytes (remember aLt= Liver) whereas the AST is found in more places.
Bilirubin is a function of hemolysis, hematoma, metabolic diseases, and biliary tract obstruction?.among other things. If the bili is moderately high- 1.5 to 3 or so?and it means nothing especially if they are a trauma or hemorrhagic stroke victim who has bled and is being transfused or undergoing normal erythropoiesis in response to blood loss. It would help know a "direct" (from the liver) versus "indirect" bilirubin? If the high bilirubin is "indirect" in nature-- it has very little or nothing to do with the liver.
The transaminases can tell us more meaningful information. A hallmark of alcoholic liver disease is an AST:ALT ratio of 2:1 or greater. In fact, life insurance companies use this to screen people and raise premiums. In viral hepatitis, both will usually be elevated at closer to the 1:1 ratio?.or the ALT even higher than the AST. The elevation is not usually very marked- one study found that the "mean" ALT of a group of people with HepC was 104. Of course, none of this is pathognomonic- and mildly elevated transaminases are also seen in NASH and drug related hepatitis.
We can get other info from the Alk Phos and GGT. Alk phos is nonspecific as it is seen in the bone, kidney, liver, leukocytes, etc. If it is high, a GGT can be added to see if it is likely liver in origin (GGT also high). GGT is also often high in alcoholic liver disease.
When you see someone otherwise young and healthy with SKY HIGH transaminases (like in the 700+ range)?.this is suggestive of a severe acute hepatic injury. Tylenol was a likely culprit (there are other drugs that do the same thing but Tylenol is common) given the suspicion in that case for drug overdose.
In general, the AST and ALT aren't actually "function" tests (albumin, bilirubin, and INR are!). AST and ALT are two enzymes that "live" in hepatocytes. When the hepatocytes are damaged, and rupture/die/undergo apoptosis/necrose/damage, they release AST and ALT into the bloodstream.
It certainly helps when the AST/ALT are "trending down" because this means the damage to the liver is not "ongoing" and has slowed or stopped. If they keep rising, it is not good at all- as we already know.
Sometimes, all of the hepatocytes are SO injured and leak all of their AST and ALT, that there are no cells left to "be injured". The transaminases start "coming down"...but the injury has happened. Livers can "regenerate" but it takes weeks to months for it to start.
In the cirrhotics, you'll notice they usually have "normal transaminases". yet their livers don't function at all. This is why transaminases aren't really "liver function tests". The cirrhotics will have horrific bilirubin, INR, albumins, but normal AST/ALT. Their livers are so damaged and burnt out from the years of damage, that they can't even spill AST/ALT much anymore. There isn't anything left to damage. The hepatitis patients will have chronically high AST/ALT, usually in the 100-200 range, because of ongoing viral liver damage happening every day.
The "shock liver" patients (MSOF, tylenol, ischemia, etc) will have these sky high AST/ALT that indicate a much more severe issue.
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