AST, ALT, GGTP And Alkaline Phosphatase In Dogs’ And Cats’ Livers

“ALT” stands for alanine transaminase, an enzyme present in the cells of mammalian livers. While the enzyme may also be found in a few other organs, the quantities are low enough to make ALT reasonably liver-specific. The same enzyme is also known by an older name, SGPT, which stands for serum glutamic pyruvic transaminase. Normal serum level of ALT in dogs should be between 12 and 118.

Some canine liver problems can be diagnosed by blood and urine tests.

Some canine liver problems can be diagnosed by blood and urine tests.

ALT is known as a “leakage enzyme,” meaning the cells that contain it must die in order for it to be released. Therefore, if serum ALT levels are up, some death of liver cells has occurred. However, it is important to recognize that there is not a direct correlation among the elevation of the enzyme, the amount of liver damage and the prognosis for the patient. However, trends may be followed that give an indication of improvement or worsening of liver disease.

Many diseases may affect ALT, as well as non-liver conditions. For example, congestive heart failure (CHF) may result in poor blood circulation, causing stagnation of liver blood flow and poor liver function. Some medications, most notably phenobarbital used for seizure control.

“AST” stands for aspartate transaminase, which is also an enzyme. The older name is “SGOT,” which stands for serum glutamic oxaloacetic transaminase. AST is also present in the liver and several other organs including skeletal muscle, heart muscle and red blood cells. Interpretation of the enzyme is similar to ALT, while recognizing that it is much less liver-specific. Normal level in dogs is 15-66.

Alkaline phosphatase is also present in the liver, as well as bone, placenta and other locations. From the liver, it normally moves into the intestinal tract along with bile through the bile ducts. However, if bile flow is obstructed, levels within the liver may rise sufficiently to ‘back up” into the bloodstream. Patients with rapidly growing bones, puppies and kittens, as well as pregnant animals, may have elevated alkaline phosphatase levels.

Bile ducts may become obstructed at the microscopic level, inside the liver, or the macroscopic level, in the large ducts that leave the gall bladder, pass through the pancreas and enter the intestinal tract, where bile aids in the digestion of fats.

GGTP or gamma glutamyl transpeptidase, also becomes elevated in biliary obstruction, and is much more specific than alkaline phosphatase. It is also a much newer test.

It is important to realize that these are not measurements of liver function, rather they are measurements of liver damage. Now, that won’t keep physicians or veterinarians from calling them liver function tests. It’s not that we don’t know better, it’s just the term used as an inappropriate shortcut. To assess the function of the liver, we will discuss bile acids in this series.

See you tomorrow, Dr. Randolph.

2 thoughts on “AST, ALT, GGTP And Alkaline Phosphatase In Dogs’ And Cats’ Livers

  1. Alice C.

    Hello Dr. Randolph, I am interested in knowing anything you have to offer in the form of information or advice about my 9 year old beloved Zoey, a dachshund mix. She has always struggled with her weight somewhat but is active and loves her walks and to play fetch. She has slowed down somewhat and loves to smell the flowers on the walks a little more in her golden years but otherwise, she is happy and healthy as she always has been. She is on Castor and Pollux Organix weight management food, takes a fish oil supplement and Glucosamine and Chondroitin with her breakfast every day. Her drinking and eating level seems the same. No diarrhea, vomiting, or lethargy. Her coat is still in great shape but in the last two years she’s begun to bite and itch a little more around her joints and belly. Her skin under her belly seems to me to look a little like “crocodile skin” in that it’s dry, but there’s no flaking or areas of redness, bumps, swelling, etc. Occasionally she bites at her feet as she’s trying to “scratch an itch”. The veterinarians she’s seen have all said she might have a slight allergy because of the area we live in (Virginia Beach, VA) and I now have a medicated shampoo to wash her with every other day on the affected areas along with my other dog who bites his feet quite often too.
    I noticed her randomly panting slightly more than normal about a month ago and with her being older, I took a look at a few sites to see if there was a reason for this. That’s when I came upon the possible idea that she could be starting to slowly show signs of Cushing’s. This past summer, she hurt her knee as she likes to “launch at things” that she thinks are dangerous…gotta’ love the dachshund spunk! I took her to the animal chiropractor in our area and he was able to stabilize the knee without surgery and she has shown no signs of pain or limping since. I have steps up to the couch and bed and make sure she doesn’t jump off anything. It seems her back legs might be a little weaker than when she was younger because she tries to “rev up” before she comes up on things, as if it’s a little tougher now.
    I took her to the veterinarian last week for vaccines and a wellness exam and asked for bloodwork. It showed she had elevated Alkaline Phosphate and GGTP levels in her blood. According to my searches, it seems quite possible that my intuition was correct about her having Cushing’s. The veterinarian said to put her on a daily dose of Denamarin (I am waiting for the pills to arrive in the mail so I have not started those yet). She also said to have her rechecked in six months. If the levels are not down or have increased, she will do the low dose dex test and/or ultrasound to check for Cushing’s or other liver abnormalities.
    My questions to you are:
    A.) what do you think these supplements can do for her if she truly does have a liver disease and can waiting six long months be harmful to her? Should I recheck her earlier than that to see if they have had an effect on her levels?
    B.) Also, since she’s almost 100% asymptomatic, is there another possibility for these high levels? Could it be another disease not related to the liver and if so what?
    As a side note, she has never been on medications that could increase these levels such as corticosteriods. She’s always been a VERY healthy young lady.
    She’s my dearest friend and I know you hear that all the time. But, we just have a special understanding and connection I’ve never felt with another dog. She’s a one of a kind and I need her in my life.
    I desperately want her to be ok and feel well, and I want to be a good friend and mom to her by doing all I can for her. Please advise. I would truly appreciate it.
    Thank you for your time, Alice

    Reply
    1. Dr. James W. Randolph Post author

      My questions to you are:
      A.) what do you think these supplements can do for her if she truly does have a liver disease and can waiting six long months be harmful to her? Should I recheck her earlier than that to see if they have had an effect on her levels?
      Denamarin is a cousin nutraceutical to Denosyl. You can read about Denosyl by clicking here. You can have similar expectations from Denamarin as from Denosyl.
      B.) Also, since she’s almost 100% asymptomatic, is there another possibility for these high levels? Could it be another disease not related to the liver and if so what? As noted in the post above, Alkaline Phosphatase is NOT specific for the liver, even though we first suspect the liver whenever the AlkPhos enzyme is elevated. That said, there are several other sources for alkaline phosphatase in the body. It is also not uncommon for a nine-year-old of any breed to have elevated alkaline phosphatase levels.
      An easy screening test for Cushing’s Disease is the urine cortisol:creatinine ratio. Obtain a urine sample, submit it to a laboratory, and in a few days or less you will have a result. IF the result is negative, the likelihood of Cushing’s Disease is near zero. Positive tests will require more testing, such as the ACTH stimulation test and/or low-dose dexamethasone suppression test.
      She’s my dearest friend and I know you hear that all the time.
      Yes, we do, but we never tire of it!

      Reply

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