Reading a Chemistry, Cl / Chlorine

Chloride is an extracellular anion that helps with water balance (osmality), is necessary for spinal fluid production, and helps transport other ions across cellular membranes.  Chloride is a required nutrient and is often balanced with sodium.

Since Cl and Na both control osmality they'll shift out of the blood stream when water moves out.  For this reason, Chloride changes are often corrected by using the following formula:  Corrected Cl = (normal Na/measured Na) x measured C. 

Increased chlorine or "hyperchloremia" may be caused by:
- Shift of water:If the corrected Chloride falls in the normal range the change is due to a shift of water within the body.
-Pseudohyperchloremia: due to the administration of or a dietary increase of bromide which is read as chloride by some Chem machines.
-Drugs: diuretics will cause hyperchloremia as will the administration of chloride-containing fluids.
-Kidney issues: renal failure or renal tubular acidosis.
-Addison's disease
-Diabetic ketoacidosis
-Chronic respiratory alkalosis

Decreased chlorine or "hypochloremia" may be caused by:
-Vomiting: if chloride is low relative to sodium vomiting may be the reason.  Part of what makes stomach acid so acidic is an increase of chloride, so if chloride is being lost without sodium, vomiting could be the cause.
-Intestinal issues: such as diarrhea.  Chloride is absorbed in the large intestine of horses, so if there's an absorption issue chloride may be low.
-Kidney disease: may cause hypochloremia, especially in cattle.
-Too much sodium: such as from the administration of sodium-containing fluids may cause chloride to be low compared to sodium.

Reading a Chemistry, K / Potassium

Potassium is an intracellular cation although it is passed across cell membranes to alter cell polarity.  It plays a key role in cardiac rhythm and rate, the kidney's ability to handle sodium, and acid-base metabolism.  Potassium and sodium absorption and excretion are usually tied to one another, so excesses or deficiencies of one of these electrolytes often effects the other.

Increased potassium or "hyperkalemia" may occur due to:
-Artifact: due to sample clotting (K is released for platelets as they clot) or hemolysis especially in horses and pigs (since potassium is found in high concentrations inside of cells, when the cells are lysed the potassium leaks out making it appear that there is more potassium in the extracellular fluid than expected)
-Cell rupture: due to over-exercise, tissue necrosis, etc.
-Leukocytosis: very high WBC counts can result in hyperkalemia due to cell leakage.
-Drugs: Trimethoprim induces hyperkalemia by inhibiting sodium resorption in the cortical collecting ducts of the kidney.
-Metabolic acidosis: potassium gets redistributed as the body tries to deal with the acidosis.
-Decreased renal excretion: in cases of oliguria or anuria such as blocked toms.
-Ruptured urinary bladder: if this is the case Na and Cl will be low (hyponatremia and hypochloremia)
-Inherited conditions: such as Hyperkalemic polymyopathy of horses.

*Observe your patient: Hyperkalemia will result in cardiac malfunction and generalized muscle weakness. 

Decreased potassium or "hypokalemia" may occur due to:
-Artifact: lipemia may cause a pseudohypokalemia
-Decreased intake: due to dietary insufficiency, anorexia,
-Redistribution: this may occur due to hormones including insulin and catecholamine so it can be brought on via bolus glucose administration, stress, or excitement.
-Fecal loss: if large amounts of sodium are being absorbed in the large intestine large amounts of potassium may be lost.
 -Renal losses: Increased GFR in the kidney: this will decrease reabsorption leading to hypokalemia.  Increased sodium excretion by the kidney: potassium is excreted along with sodium.
-Metabolic alkalosis
-Mineralcorticoids: such as aldosterone increase renal tubular resorption of sodium can result in potassium excretion by the kidney.  This can be due to administration of drugs, neoplasia, or other disorders.

*Observe your patient: Hypokalemia can result in restlessness, generalized muscle weakness, cardiac arrhythmia and death.

Reading a Chemistry, Na / Sodium

Sodium is an extracellular cation.  It drives the movement of fluid between epithelial surfaces within the body and also plays a key role in creating neural impulses, muscle contractions, and secretions.

Increased sodium "hypernatremia" may be caused by:
-Excessive intake: dietary or via fluid therapy.  Signs of this often include increased urine volume and signs of dehydration.
-Dehydration: (relative increase meaning that the concentration is high only because of the water loss and referred to as pseudohypernatremia).  In many cases of dehydration, however, sodium levels are normal.

Decreased sodium "hyponatremia" may be caused by:
-Artifact: if the sample was lipemic or hyperproteinemic
-Excessive water intake: In this case the GFR is increased so that sodium cannot be resorbed.
-Water retention: due to congestive heart failure, liver disease, nephrotic syndrome or advanced renal failure.
-Renal issues: lack of aldosterone, proximal renal tubule dysfunction (resulting in reduced sodium absorption) in renal disease (especially in horses and cattle), osmotic losses due to polyuria (diabetes mellitus), and diuretic therapy. Cattle with renal failure have a consistent moderate to marked hyponatremia.
-Gastrointestinal issues: sodium may be lost due to diarrhea, especially in cattle.
-Addison's disease (hypoadrenocorticism): 

Reading a Chemistry, ALP

ALP can help diagnose cholestasis, but it is not liver specific in most animals.  It is also found in bone, intestine, kidney, mammary and placental tissues.  So when ALP is elevated the origin could be in the liver or any of these other tissues.

ALP elevation may be caused by:
-Cholestasis
-Liver disease
-Bone disease: increased osteoblastic activity due to hyperparathyroidism, osteosarcoma, a healing fracture (in dogs).
-Increased cortisol: due to steroid administration (such as prednisone) or due to Cushings (hyperadrenocorticism). This is less likely in cats

Reading a Chemistry, ALT

ALT is an enzyme that is found on the inside of liver cells.  So, when liver cells get damaged it leaks out and the levels become elevated in the blood.  ALT is specific to the liver, so it is a good indicator of liver damage, but it is only useful in dogs, cats, rabbits and primates.  Large animals have very little ALT so SDH and GLDH are used instead.

Increased ALT can be caused by:
-Artifact: In cats hemolysis can result in elevated ALT levels when no liver damage is present.
-Drugs: Anti-seizure medication such as primidone, phenobarbitone, dilantin will increase ALT levels up to four times normal. Corticosteroids increase ALT up to 2-3 x normal. Any other drugs that cause hepatotoxicity may also raise ALT such as: tetracycline in cats, caparsolate in dogs, or acetaminophen.
-Liver disease: conditions that alter cell membrane permeability or cause necrosis will cause ALT levels to rise and ALT will usually be higher than AST in cases of liver disease.
-Bile duct obstruction: if bile backs up it will begin breaking down tissue which may lead to elevated ALT.
-Trauma: if liver cells are hurt or destroyed ALT levels may become elevated.
-Muscle disease: in severe cases such as ischemic myopathy in cats, muscular dystrophy in dogs ALT my become elevated but AST and CK levels will rise to a much greater degree.
-Cancer: hepatic neoplasia can also cause ALT levels to rise although in this case AST is usually higher than ALT.


Decreased ALT can be caused by:
There is no such thing as ALT levels that are "too low".

Reading a Chemistry, Chol / Cholesterol

Cholesterol is form of lipid that is made by the liver.  It is a component of cell membranes and is used to create hormones as well.

Causes of high cholesterol include:
-Hormone disorders: hypothyroidism or hyperadrenocorticism may cause high cholesterol with normal serum triglycerides.
-Kidney disease: such as nephrotic syndrome
-Pancreatitis: in this case both serum triglycerides and cholesterol will be high.
-Diabetes mellitus: in this case both serum triglycerides and cholesterol will be high.  Of course, blood glucose should be checked to further confirm this as a possible diagnosis.
-Liver issues: especially cholestasis.  This is because the liver is primarily responsible for cholesterol excretion.  With liver issues both serum triglycerides and cholesterol will be high.

* It is worth noting that high cholesterol does not put animals at risk for heart or blood vessel problems like it does in humans.

Causes of low cholesterol include:
-Liver issues: the liver synthesizes cholesterol, so if it isn't functioning properly blood cholesterol may be low.  If cholestasis is present as well, however, cholesterol cannot be excreted so the lack of synthesis and lack of excretion may cancel each other out and give a normal result.
-Hyperthyroidism
-Malabsorption: such as EPI (exocrine pancreatic insufficiency).  In this case serum triglycerides will also be low.

Reading a Chemistry, T. Bili / Total Bilirubin

Reading a Chemistry, Glob / Globulins

Globulins are the second most common protein in serum or plasma.  They are responsible for the body's immune functions.

Increased globulins or "hyperglobulinemia" may result from:
-Immune system stimulation: from infection or allergies.
-Stress
-Dehydration: this is a relative increase meaning that the amount of globulin is normal, but it is more concentrated due to the lack of water.  This is likely the case if albumin is also increased.
-Liver disease
-Heart disease
-Arthritis
-Diabetes

Decreased globulins may result from:
-Immune system suppression: due to corticosteroid use,r stress, or infectious disease.

Reading a Chemistry, Albumin

Albumin is made by the liver and is the most plentiful of the plasma or serum proteins.  As a natural colloid it plays a major role in maintaining vascular volume.

Causes of increased albumin:
-Dehydration: is the only cause of increased albumin.

Causes of decreased albumin:
-Liver issues: if liver function is impaired albumin may not be produced.
-Kidney disease: albumin may be lost by a leaky glomerulus
-Blood loss: even if RBC's are normal.  The spleen sequesters a reserve of red blood cells, but there is no such reserve for albumin, so shortly after a major blood loss albumin will be decreased, but the red blood cell count may not be.

Reading a Chemistry, Phosphorous

Phosphorous exists in the intracellular fluid, in bone, and elsewhere.  It is usually balanced with calcium in the body so it's regulated by PTH (parathyroid hormone) and calcitonin.  It also plays a part in acid-base metabolism.

Increased phosphorous "hyperphosphatemia" may be caused by:
-Cellular damage: due to the intracellular phosphorous leaking out.
-Over-administration of phosphorous: via phosphorous containing fluids, foods, or enemas.
-Renal issues: reductions in renal blood flow or GFR will cause more phosphorous than normal to be reabsorbed.
-Ruptured bladder: phosphorous from the urine is reabsorbed from the abdomen and ends up back in the blood.

Decreased phosphorous "hypophosphatemia" may be caused by:
-Increased use: increased cellular uptake of phosphorous due to accelerated metabolism
-Decreased intake
-Over-administration of binders: such as during treatment for chronic renal failure or antacids that bind with phosphate.
-Alkalosis

Reading a Chemistry, Ca / Calcium

Calcium is balanced in the body by ParaThyroid Hormone (PTH) which stimulates bone breakdown in order to increase the calcium levels in the blood when they are low and calcitonin which stimulates the storage of calcium in the bone thereby decreasing blood calcium.

Increased blood calcium "hypercalcemia" may be caused by:
-Overactive parathyroid: (hyperparathyroidism) due to cancer or hypoadrenocorticism.
-Cancer: Increased calcium raises a red flag for lymphoma, myeloma, osteosarcoma, some adenocarcinomas, or other types of cancers.
-Diet: vitamin D toxicity.
-Renal failure

Decreased blood calcium "hypocalcemia" may be caused by:
-Eclampsia: the demands of milk production may result in hypocalcemia.
-Diet: calcium or vitamin D deficiency.
-Loop diuretics: result in loss of calcium.
-Stress
-Pancreatitis
-Renal failure
-Tissue degradation: as happens with circulatory shock or heat stress.
-Hypercalcitoninism: too much calcitonin (rare).
-Secondary to other issues: such as hypoalbuminemia or acid-base imbalances

Reading a Chemistry, Crea / Creatinine

Creatinine is a product of muscle breakdown.  In healthy animals the rate of muscle breakdown and, therefore, creatinine release into the blood is fairly steady.  It is filtered out of the blood by the kidney and reabsorption does not occur as it does with BUN.  Because it is not influenced by an animal's diet or the GFR of the kidney, it is a more reliable test for kidney function than BUN although they are often both analyzed together.

Increased creatinine may be caused by:
-Kidney failure: if the kidney isn't functioning properly it won't filter the creatinine out of the blood and it will build up.
-Muscle damage: increased creatinine values would be expected in animals with muscle damage such as hit-by-car cases or animals that have recently been over-exercised.

Decreased creatinine levels may be caused by:
-Decreased muscle mass: less muscle will result in less metabolism and, therefore, less creatinine produced.

Reading a Chemistry, BUN / Blood Urea Nitrogen

When the body digests protein ammonia is produced as a waste product.  If you can imagine the ammonia you buy at the store, it is a very caustic substance that definitely should not be coursing around the body.  So, the liver quickly absorbs it and converts it to urea, a less toxic waste product.  The urea is released into the blood and then filtered out by the kidney and concentrated to make urine.  BUN, then, is often used to check kidney function.

Increased BUN may be caused by:
-Kidney disease: BUN will build up in the blood if the kidneys are not filtering it out properly.
-Decreased GFR: or glomerular filtration rate.  This means the kidney is filtering the blood more slowly than usual.  This allows substances such as BUN to be re-absorbed at a greater rate than they would normally be, resulting in higher than usual concentrations of BUN in the blood.
-High protein diets: more protein equals more waste.  Because this test can be influenced by an animal's diet it isn't reliable on its own.  This is why BUN and Creatinine are often looked at together.
-Tissue damage: when the body's own proteins are damaged or destroyed by fever or necrosis it digests them.  Large amounts of damage may increase the BUN.


Decreased BUN may be caused by:
-Low protein diet: less protein means less BUN produced.  Because this test can be influenced by an animal's diet it isn't reliable on its own.  This is why BUN and Creatinine are often looked at together.
-Liver disease: if the liver is not functioning it won't produce the urea that results in BUN.  Of course, if this is suspected ammonia should be looked at as well.  If it isn't being converted to BUN, than it should be building up in the blood.

Reading a Chemistry, Glucose

Glucose is commonly called blood sugar.  It can be tested with a Chem machine or with a handheld glucometer.  It should be noted, however, that due to various reasons, glucometer readings may vary greating from those found on a Chem test.  For monitoring purposes, a tech should choose one machine and use it exclusively to get consistent results; ideally the Chem machine may be used for accuracy or the owner's glucometer may be used for consistency.


Increased glucose or "hyperglycemia" may be caused by:
-Diabetes mellitus:  Glucose is often used to indirectly monitor insulin.  This is because cells cannot consume the glucose in the blood without the presence of insulin, often described as the "key" to allow glucose into the cell.  So, when the body stops producing insulin (diabetes melletus), glucose cannot be used by the cells and begins building up in the blood.  Hyperglycemia on a fasting blood test very likely indicates diabetes mellitus.
-Pancreatitis
-Drug-induced:  prolonged use of steroids or morphine may cause hyperglycemia.
-Stress: this means that more than one blood test may be needed to diagnose diabetes mellitus.

Decreased glucose or "hypoglycemia" may be caused by:
-Too much insulin given:  if the animal is being treated for diabetes the cause of low blood sugar is likely that the animal was given too much insulin relative to what it ate.  The short-term fix might be giving an extra meal in minor cases, giving sugar water, or in the case of dangerously low blood sugar IV administration of dextrose or in a home setting, rubbing karo syrup (corn syrup) on the gums and mucous membranes of the mouth.
-Starvation: the body runs out of fuel and cannot keep up with the demand for glucose.
-Artifact:  when blood is drawn it contains living cells.  If those cells are left to sit, even after spinning, before the test is run, they continue to use glucose.  So, if you want a good glucose reading the blood must be processed and the test run promptly or, if a delay is unavoidable, you can spin the blood, then draw off the serum and freeze it for later testing.
-Advanced liver disease: the liver produces and stores glycogen which can be quickly converted to glucose, and thus serves as a reserve for glucose.  If over 70% of the liver's function is lost it may not be able to produce or store this reserve and hypoglycemia may result.
-Insulinoma: an insulin-producing tumor that results in increased glucose use within the body.
-Sepsis: infection can cause increased glucose utilization.
-Pregnancy toxemia: especially in bovine, in late pregnancy, ketosis may occur due to the demands of the growing fetus.
-Addison's disease: results in decreased glucogenesis and increased glucose use by skeletal muscle.

 

Reading a CBC: TP / Total Protein or TS / Total Solids

Total protein refers to the total serum or plasma protein and can be determined by machine or very simply by taking the microhematocrit tube that you used for your PCV and breaking it at the level of the serum or plasma and then placing a drop onto a refractometer.

Serum total protein contains albumin and globulins while plasma total protein will also contain fibrinogen and other proteins, so it is important to know what type of sample you have when looking up results.  Just remember that serum comes from blood without any anticoagulants added, and plasma comes from blood with anticoagulants such as from "purple-top" tubes which contain a coagulant called EDTA or "green-top tubes" which contain heparin.  Also note that some microhematocrit tubes come coated with heparin as an anticoagulant.

Increased total protein may be caused by:
-Dehydration: this is a false or "relative" increase.  The amount of protein is actually normal, but the amount of water it is diluted in is decreased.  It's like adding a teaspoon of instant coffee to a half a cup of hot water instead of a full cup.  The amount of coffee is the same, but the concentration is higher.
-Chronic immune stimulation: either from illness, infection, or immune system disorders.
-Cancer: plasma cell myeloma



Decreased total protein may be caused by:
-Overhydration: as with fluid therapy.
-Liver disease: the liver is responsible for making albumin and many clotting proteins.
-Renal disease: protein loss in the urine.
-GI issues: protein losing enteropathies, exocrine pancreatic insufficiency
-Loss: via internal or external bleeding (even with normal RBC counts due to the reserve of RBC's in the spleen -there is no such reserve for blood proteins and so, this can be a first sign).  Proteins may also be lost through exudates such as with severe burns.
-Malnutrition: the body has nothing to make proteins with.

Reading a CBC, Platelets / PLT

Platelets are also called "thrombocytes" and are often counted by machines, but can also be counted on hemocytometers or during manual diffs and then they can be calculated as follows:

(Platelets/100 leukocytes) X (WBC count/mcg) = Platelets/mcg

Here's what a thrombocyte looks like:

Platelets are essential in the body's ability to form a clot when bleeding occurs.

Increased platelets or "thrombocytosis" can be caused by:-Excitement: epinephrine release can cause the number of platelets to increase temporarily.
-Infections
-Inflammation
-Acute or chronic blood loss: the platelets are lost along with the blood.
-Drugs: such as steroids.
-Hyperadrenocorticism: overactive adrenal glands.
-Splenectomy: the spleen is responsible for destroying old platelets which may remain in circulation if the spleen has been removed or is not functioning properly.
-Cancer
-Discontinuation of chemotherapy.

Decreased platelets or "thrombocytopenia" can be caused by:-Decreased production: of platelets by the bone marrow.
-Clotting: the platelets may be used up due to extensive clotting.
-Immune disorder: the immune system may attack its own platelets.
-Sequestration: removal of platelets from the general circulation, possibly due to splenomegaly (an enlarged spleen).