Vet School 101 Blood work: What it means and why your pet needs it (Part 2: Blood Chemistry)
Turns out this topic is gathering some steam here on Dolittler––as it is in veterinary minds across the spectrum of companion animal medicine. That’s why this topic requires a two-post treatment to properly address.
Though blood work is an increasingly common component of every pet’s medical care, not every veterinarian will draw your pet’s blood automatically. That’s why you need to understand why we do so and what we hope to learn by gathering this kind of [sometimes expensive] evidence.
For your better understanding, here are the typical reasons we’ll go so far as to poke your pet and recover their “red gold”:
- Because he’s sick and we’re unsure why or need more information about how his body is responding to a certain disease or process.
- Because her disease is worsening or improving in ways we need to measure so that we can adjust our treatments (medications, etc.).
- Because we’re considering a treatment regimen for your pet that requires long-term medications that can do damage to pets with certain risk factors (such as pain relievers for osteoarthritis in pets with pre-existing liver or kidney disease).
- Because your pet needs an anesthetic procedure and we want her to be as safe as possible throughout this process. Some diseases or disorders require that we change our protocols or defer anesthesia should they be present.
- Because we like to keep an annual record of your pet’s basic bodily functions and blood work is one way to objectively measure these. Keeping track of how these change is often crucial to how we optimize your pet’s care.
That said, let me first reiterate: The most common kinds of blood work are aimed at comprehensively testing the body’s functions and searching for signs of disease and disorder. They include the CBC (see yesterday’s post) and blood chemistry (AKA, “chemistry” or “chem”).
If the CBC (complete blood count) tests the blood cells themselves, the blood chemistry is all about testing the fluid the blood cells utilize to course through a pet’s body. This fluid’s components reflect the chemical elements utilized, filtered or produced by certain organs, thereby offering up information on their basic health and potential “dis-ease.”
Makes sense, right?
More specifically, here are the “chemicals” we like to measure most commonly and why:
LIVER FUNCTION
These elements indicate, in a general way, how well a pet’s liver is functioning.
- alkaline phosphatase (“alk phos,” SAP or ALP)
Liver injury, drugs, bone injury, skeletal diseases, cancer, pregnancy and normal growth can all elevate this enzyme’s level. Gastrointestinal diseases and endocrine diseases (like Cushing’s) can also raise its levels. Too low? Protein and vitamin deficiency (and severe, end-stage liver disease) can deplete it.
- alanine transaminase (alanine aminotransferase, ALT)
Toxins, drugs, liver damage and kidney infections can all raise it. Decreased bile flow can drop it (as when a liver is “congested”). Mild elevations don’t stress us (in the absence of symptoms), but follow-up blood work is always necessary in these cases.
- bilirubin total (T Bili)
Toxicity (poisoning), some forms of anemia and liver disease can all raise this measure of bile pigment (produced by the liver). Certain kinds of malnutrition, too-fatty diets and an end-stage, diseased liver may be accompanied by its low levels.
- albumin
This protein is produced by the liver. As such, its depletion tells us something might be up with this organ. But malnutrition can do it, too. Fever, infection, burns, swelling and low calcium levels are also likely to drop albumin levels. While rarely elevated, severe dehydration may sometimes raise it a bit.
KIDNEY FUNCTION
When we say we’re testing your pet’s kidney function with blood work, these are the most common tests we look at.
- blood urea nitrogen (BUN)
Kidney damage is what we think of first when the BUN (usually pronounced “B.U.N.”, not “bun”) is up. But certain drugs, intestinal bleeding, excessive protein intake, dehydration and extreme exercise can raise it. When it’s low, we tend to think poor nutrition, poor gastrointestinal absorption or even liver damage in some cases.
- creatinine
Because the kidneys are supposed to filter out this chemical, its elevation always points us in the direction of kidney damage or dehydration. Muscle breakdown (as with extreme exercise) can also flood the body with creatinine while certain drugs can impair the kidney’s filtration of it. Confusingly, low levels may indicate kidney damage, protein starvation, liver disease, or pregnancy.
- creatine kinase (CK, CPK)
This enzyme usually indicates either kidney trouble, dehydration or muscle breakdown, as with extreme stress, injury or exercise.
ELECTROLYTES
These individual elements are measured to determine the interaction of a myriad of complex processes. They may go along with certain illnesses or disorders and knowing their true value helps us guide our treatment options, especially when it comes to fluid therapy.
- sodium
Sodium (Na) is lost with vomiting and diarrhea. It can help indicate a pet's hydration status. Pets with Addison's disease and kidney disease may also have low levels.
- potassium
Low levels of potassium (K) are seen with acute vomiting and diarrhea. Kidney failure and other kidney troubles, Addison's disease, dehydration and urinary obstruction will raise it. Extremely high levels, as we often see in "blocked" cats can lead to deadly cardiac arrhythmias.
- chloride
Chloride (abbreviated Cl) is often low in acute vomiting. Addison's disease patients will also show lower levels. Elevations are commonly associated with dehydration.
PANCREATIC FUNCTION
The pancreas is a sensitive gastrointestinal and endocrine (hormone-producing) organ that’s easily insulted. Pets with high levels of the following two enzymes may be experiencing acute (sudden-onset) or chronic (long-standing) pancreatitis. High amylase levels can also be associated with kidney diseases.
- amylase
- lipase
OTHER BASICS
- glucose
Got diabetes? Stressed? Depleted your blood sugar with seizures? Has your tiny-breed puppy suddenly collapsed? Has she perhaps eaten some poisons (like Xylitol)? Glucose is the go-to test for so many troubles it’s impossible to list them all here. In any case, this “blood sugar” molecule, whether too high or too low, is a common indicator of mild and serious problems, alike.
- total protein
Vomiting, diarrhea, liver disease, poor nutritional gastrointestinal malabsorption, dehydration will all raise it. Lupus, liver disease, chronic infections and leukemia will all drop it.
- calcium
Calcium (Ca) levels can indicate a variety of disease processes. Some tumors, certain hormonal diseases (hyperparathyroidism) and kidney disease can all affect this value.
***
That’s my summary. But don’t be fooled: the complex interaction of components in the blood, coupled with other processes as they invariably are, may make interpreting these findings not-so straightforward (and that's an understatement). When one goes up, another may come down––and vice-versa.
That’s why an understanding of these test results is a necessarily “holistic” process in which we take our individual patients’ findings (on physical, CBC, other lab tests, X-rays and/or more sophisticated imaging) and put them all together. Even then, it’s nowhere like it is on Star Trek.
Sigh...if I only had a Tricorder...
May 3rd, 2009
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Add Comment24 Comments
This is the best way I've ever seen blood chemistry explained - thank you!
Ingrid King May 3rd, 2009 11:57:43 AM
Very nice posts - lots of information. I always request testing prior to surgery for any age dog. I had a very bad experience in the 1980's when a young healthy female died after a routine spay. I picked her up from the clinic and about 15 minutes after I got home I left for the ER with her because she was lethargic and the incision was oozing blood. She bled to death at the ER, allegedly from an inherited blood disorder. I can still see her face. I have never gotten over it.
Jody May 3rd, 2009 12:19:06 PM
Jody: I am so sorry, most likely vWD, fortunately now can be tested in most breeds genetically.
I know how I felt, when finally able to review a weeks worth of blood panels & PCV on Pocket. Like a hard kick in my gut! Particularly, when I faithfully monitored her blood work , her entire life.
Pocket's Story from New Hampshire
If it should help others, this is what a hopeless case of liver & kidney failure can present as. I have no objection to discussion, as it is you are all "anonymous"
Barbara A. Albright/NH May 3rd, 2009 12:45:11 PM
Thanks, Dr. Patty, for this excellent two-parter--and for the caveat that interpreting blood work, like all diagnostics, is as much art as science. Here's one example of how interdependent diagnostic tools can be, for good or ill. When my then-20 month-old Scottie suddenly became violently ill, blood work showed all of her liver values to be sky high. An abdominal sonogram performed by a board certified radiologist resulted in a diagnosis of acute (and also possibly chronic) pancreatitis. Treatment for this condition resulted, within a week, in my dog's liver values coming down 50%. This decline was misleading, however: Within two weeks she was dead from what necropsy revealed to be end-stage liver disease--while her pancreas was unremarkable, her liver was 100% cirrhotic. Those declining liver enzymes? Merely an indication that her liver was shutting down.
Lisa in Cape May County, NJ May 3rd, 2009 02:08:54 PM
Thanks so much for sharing this detailed explanation!! It's very helpful information.
karen May 3rd, 2009 02:55:33 PM
Ahhh, Lisa in Cape May: The Scottish Terrier weakness : the liver! How we know it well & wish we could unlock the reasons.
My Zoe's pup (Pocket's 1/2 sis) has just been diagnosed with chronic hepatitis/cirrhosis at age 9.
Pocket's seemingly high liver enzymes on her 6 day blood panel at Dover Veterinary Hospital, are also misleading, when infact, they had declined from previous years by more than 50%--- something Edgefield Veterinary Hospital was well aware of, since they had years of comparison.
Good reminder of how years of progression is applicable, particularly from baselines.
Barbara A. Albright/NH May 3rd, 2009 03:39:38 PM
I may save this post for when I have to look at human blood test results. ;)
Seriously, very informative and interesting. Having had a cat with hepatic lipidosis secondary to pancreatitis (he recovered! Thanks South Paws!) about 14 years ago, blood tests were the primary tool the doctors had. Was the liver functioning properly? How well? Was there still infection present? His only outward symptoms were loss of appetite and lethargy. Without blood work, they would have been working with a blindfold on.
Susan Rosenau May 3rd, 2009 06:23:55 PM
Aren't the electrolytes sodium, potassium and chloride.. rather than calcium..
Elizabeth - from Nova Scotia May 3rd, 2009 08:48:47 PM
This is probably a weird question, but what is the general price range that a basic blood panel should be falling into? I realize that it varies hugely, but... just a range? During the food recall, Mal had eaten some recalled treats and (he has a touchy stomach and at the time we were fighting a constant battle against really soft poop). My vet thought I was overreacting when I asked her to run the test. I was changed over $200 for it (in addition to a blood draw fee and very high office visit fee which kind of annoyed me since he didn't get an exam and we never actually SAW a vet - a tech did the blood draw and we were in and out in half an hour!), and while I don't mind doing that for a senior dog, that's kind of a hit to run routinely on every one, especially when fosters get added in (and EVERYONE has raised their office visit fees this year.)
Cait May 3rd, 2009 08:59:31 PM
Lisa - I'm so sorry to hear about your experience. We've learned from similar cases to get second and even third opinions from other vets throughout the diagnostic and treatment process. Sadly, we too have learned the hard way. :O(
Cait - You're right - it varies... GREATLY. $200 is pretty standard in my city. However, one city over, where we take our own pets, I pay $80 for a senior wellness panel (CBC+T4), an extra $20 for a full thyroid panel and an additional $65 for a full chem. Blood draw is included in the price. These prices are also in CDN dollars, not US. These are all sent out.
Kim May 3rd, 2009 09:53:50 PM
Kim--
You know, three vets examined and treated our puppy. We could not have saved her, even absent the misdiagnosis. Judging from the state of her liver at necropsy, she came into the world with congenital liver failure. Losing her was, nonetheless, a heartbreaker. I remember asking my vet why we should even resort to sonograms if they can be so equivocal. With a tone of regret in her voice, she answered: "Because we have nothing better."
Lisa in Cape May County, NJ May 3rd, 2009 10:33:07 PM
Lisa in Cape May: Did any of the 3 suggest a biopsy? Of either the liver or pancreas? And upon necropsy, were internal small shunts found?
Since Liver shunt has been diagnosed in the Scottish Terrier more than once, that would have been a natural suspect. Also copper storage disease in the Scottie not unheard of. Twenty months would still not be suprising for either diagnosis.
Very curious.
Barb A./NH May 3rd, 2009 10:55:21 PM
Barb--
No, no one suggested that a biopsy was in order. No evidence of liver shunt appeared upon necropsy. One canine liver expert I consulted with did suggest copper storage disease as a possibility. This puppy did come from a litter struck by parvo at ten weeks. During this period one littermate died, not from the usual dehydration, but from splenetic hemorrhage. These are the only clues we have. Very curious indeed.
Lisa in Cape May County, NJ May 4th, 2009 06:30:00 AM
Elizabeth: Thanks for asking. I'm still fleshing out this post. I think it's best to include the chloride in the electrolyte group and calcium in the "other basics." I will amend to reflect, of course. Any other suggestions are welcome!!
Dr. Patty Khuly May 4th, 2009 08:31:47 AM
I'm sorry to seem like a pest, but in case anyone didn't go back to yesterday's post, I'm oing to add my last comments here as well (I don't know if the search comments function is working yet, Dr.K., so I hope you don't mind the repeat).
To add something about needing to have a vet who can understand the values/indicators, it's important to have a vet who is willing to accept that some breeds will normally have higher and lower values on certain things than other breeds. The RBC and WBC for greyounds, especially retired racers, are different than for most other breeds (most of thesighthound group in general can have higher/lower values in these tests, but racers are the best example). Some of their other values can be misinterpreted, too. I'd suggest anyone with a retired racer download a copy of 'Making Sense of Bloodwork in Greyhounds' ( http://www.greyhound-data.com/dir/446/Making_Sense_of_Blood_Work_in_Greyhounds.pdf ) by Dr. Bill Feeman, Dr. Guillermo Couto, Dr. Cristina Iazbik. They have other info, as well, (ex. http://www.animalmedicalcentreofmedina.com/library/Kidney%20Failure.pdf titled 'Does My Greyhound Really Have Kidney Failure?) which can make a difference in what treatments would - or would not - be done for the dog.Just like what Dr. K. has done in this (and the next) post,they are written to be understood by the owner and then, hopefully, a sensiblediscussion can take place with your vet.
I forgot to mention, that the Ohio State Greyhound Health and Wellness Program, is available to any greyhound owner - and any vet - at no charge - to discuss health issues, so there shouldn't be any reluctance by a vet or ownerto get in touch with them in reference to bloodwork results, or other questions of health/treatment. Go to the website (addy below) and click on 'Resources for Owners and Veterinarians' - there are FAQs right there that might answers questions, as well.
http://www.vet.ohio-state.edu/2376.htm
Of course, this program, while free, is always in need of donations to continue its work, so if anyone who needs it (or might need it in the future) has any spare change, or wants to do any fundraising events, and donate to them, that who be a mitzvah for all.
KateH May 4th, 2009 12:40:25 PM
To compare prices you have to know what is included in the panel.
So, is it a full blood chemistry including electrolytes or just a partial. For example, 6 items tested versus 17.
Is it a full CBC or a partial?
Is a urinalysis included?
Is T4/thyroid included?
Is blood pressure included? (My vet includes blood pressure in their standard senior package)
Is the test run inhouse or sent out to a lab?
Jenny May 4th, 2009 03:00:02 PM
These last two posts have been really good. I dutifully bring my cats in for yearly check-ups (as well as when something goes wrong) and they haven't had any blood work done since I adopted them 2.5 years ago. Is this something I can flat-out ask my vet for as part of their check ups?
For healthy youngish (3 in August) cats the visit includes a fecal test, weight, and then a nose-to-tail physical exam. Plus general questions about temperment, litter box usage, etc. Would I offend the doc (who I like) by asking to go beyond the standard stuff for their practice?
Anne May 4th, 2009 03:28:35 PM
Anne - I say go for it! The staff and docs at my clinic are always pleasantly surprised and enthusiastic when clients ask for (or agree to) more comprehensive wellness services for their pets - I truly believe baseline blood screening is one of the most valuable tools available for monitoring patient health, even in younger pets.
anna May 4th, 2009 03:39:52 PM
Cait - Like others have mentioned, I'd figure out exactly what you were charged for - in-house vs. ref. lab, chem12 vs. chem7, automated or manual CBC differential, T4 or no, etc...then I'd discuss with your vet (or another vet you trust, since it sounds like you were displeased with your vet's service) about which are most important and why. Then price shop for what you want, and have the results reviewed by your vet during your pet's regular visit when you're already paying an office visit fee (I'd time the panel and the visit as close together as possible). I guess some would feel uncomfortable having their vet know they went elsewhere for services, but I personally feel that if you are comparing apples to apples, and you find apples at a price elsewhere that lets you purchase more apples, more power to you - I always say, "the more money I can save while still providing good care means I can afford to provide more of it". And while I do feel vets are owed their office visit fees for their time, that time should include an exam by the doctor with you in the room...or else the procedure (like a blood draw by a tech) should be on an "outpatient" basis...just my opinion, but I'd definitely bring it up to your vet if the situation arises again. For what it's worth, at my clinic an automated CBC + chem12 + electrolyte/blood gas panel is around $115 (all in-house). In-house 3-part urinalysis is about $50, and in-house thyroid screening (T4) is about $25. The price per individual item is lower if they are pacakged together.
anna May 4th, 2009 04:03:51 PM
Anne: I agree with Anna. Not only will you be getting better care, your record may even get flagged for "above and beyond" sort of care in the future. I once worked for a hospital that would do this when clients were especially solicitous of more information and/or more aggressive diagnostics or treatment. They'd add a gold star to your file. Nice, right?
Dr. Patty Khuly May 4th, 2009 05:37:10 PM
i just happen to be busy googling for info for my project on veterinary transfusion medicine and came across this website: http://www.fetchdog.com/learn-connect/dog-resource-library/health/diagnostic-tests/D/300650/P/1:5:55:601:6103 . to be honest, i just looked at the direct coombs explanation thus far but it was excellent...so it might help if y'all want a greater understanding of the many lab tests out there.
sarahMT May 4th, 2009 08:33:36 PM
sarahMT: That is a good site, as well as the Ohio site. Must be shocking to you as well , if you have perused my Pocket's blood labs. Hard to believe that a clinic would withhold information like that from an owner and allow a dog to suffer that way. But then again, if you are used to ending pets lives inhumanely, what's a little suffering beforehand?
Especially since as a MT, education was not revolved around any kind of abuse & cruelty. Thankfully, I have no children, let alone ones interested in a NH vet tech program or undergrad UNH "animal science".
I'll never get over how "bad apples" are willing to go, and the silence & protection to enable it.
Barbara A. Albright/NH May 5th, 2009 08:11:42 PM
Good to know, this article did clear a few things up. I would never hesitate to get blood work done on any of my pets is they were acting sick or out of the ordinary. However, my vet recommended that I get a yearly blood draw done on each of my pets as a preventative measure. I am still not really sure if that is neccesary, and at $100 a pop, x 3 pets, that can add up, on top of all of the other fees and meds I get for my guys. So, is this really neccesary, or is my vet just trying to get more money out of me?
Sophie May 13th, 2009 02:19:44 AM
My 5 month old Scottie passed away two weeks ago. The diagnosis from the emergency vet we took him to were high levels of ammonia and low levels of Potassium (liver shunt). I have done research online in hind sight of this matter and it opened my eyes to liver shunt that the pet store NOR my Vet explained could be possible. It took me stumbling across a website that talked about it. Is it possible that these symptoms and death were from a genetic/ preexisting condition prior to my ownership (i.e. birth)? He went from playful to dead in 24 hours. I hate to be morbid about it, but it angers me and I'm trying to find answers that I feel the vet is trying to side step.
Dan M. May 27th, 2009 10:15:28 AM
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