Blood Chemistry
Blood tests are often performed as a biochemistry profile, or chemistry panel, which is a collection of blood tests to screen several organs at one time. The makeup of a biochemical profile varies with the laboratory in which it is performed.
The following are some of the most commonly performed chemical tests.
Albumin – is a small protein produced by the liver which acts as a sponge to hold water in the blood vessels. When blood albumin is decreased, the pressure created by the heart forcing blood through the blood vessels causes fluid to leak out.
This fluid then accumulates in either body cavities such as the abdominal cavity, or in tissues as oedema.
Albumin is decreased if the liver is damaged and cannot produce an adequate amount of albumin or if albumin is lost through damaged intestine or the urine due to kidney disease. The only cause of increased albumin is dehydration.
AG Ratio – A ratio of albumin compared to globulin
Alkaline phosphatase – is an enzyme made by the biliary tract (liver), bone and placenta and normally present in high concentrations in growing bone and in bile. It originates from many tissues in the body.
When alkaline phosphatase is increased in the bloodstream of the dog the most common causes are liver disease, bone disease or increased blood cortisol either because Prednisone or similar drug is being given to the pet because the animal has Cushing’s disease.
Alanine Aminotransferase (ALT) – is an enzyme normally present in liver and heart cells that is released into the bloodstream when the liver or heart is damaged. ALT is also called serum glutamic pyruvic transaminase (SGPT).
Liver damage causes ALT to increase in the bloodstream. ALT elevation does not provide information as to whether the liver disease is reversible or not.
Aspartate Aminotransferase (AST) – is an enzyme normally in liver and heart cells. AST is released into blood when the liver and heart is damaged.
Amylase – is a digestive enzyme formed in the pancreas. Amylase helps the body breakdown sugars. In cases of pancreatitis high levels of amylase are found in the blood.
B/C Ratio (BUN/Creatinine Ratio) – is the ratio of BUN and Creatinine in the urine. This is a very important ratio for Wheatens, since an improper ratio is one of the key indicators of protein losing syndromes.
Bile acids – are produced by the liver and are involved in fat breakdown. A bile acid test is used to evaluate the function of the liver and the blood flow to the liver.
Patients with abnormal blood flow to the liver, a condition known as portosystemic shunt will have abnormal levels of bile acids.
Blood Urea Nitrogen (BUN) or Urea – is nitrogen in the blood. This is a waste product produced by the liver from proteins from the diet, and is eliminated from the body by the kidneys.
A low BUN can be seen with liver disease and an increased BUN is seen in pets with kidney disease.
The kidneys must be damaged to the point that 75% of the kidneys are non-functional before BUN will increase. Pets that are severely dehydrated will have an increased BUN,
as the kidneys of a dehydrated patient do not get a normal amount of blood presented to them, so the waste products do not get to the kidneys to be eliminated.
Bilirubin – is a yellow fluid produced when red blood cells break down. Bilirubin is further broken down and eliminated in both the urine and stool.
Bilirubin is increased in the blood in patients with some types of liver disease, gallbladder disease or in patients who are destroying the red blood cells at a faster than normal rate (haemolysis).
Large amounts of Bilirubin in the bloodstream will give a yellow colour to non-furred parts of the body, which is called icterus or jaundice. Icterus is most easily recognised in the tissues around the eye, inside the ears and on the gums.
Calcium – is a mineral found mainly in the hard part of bones. The body has hormones, which cause bone to release calcium into the blood and to remove calcium from the blood and place it back into bone.
Abnormally high calcium in the blood occurs much more commonly than low calcium. High blood calcium is most commonly associated with cancer.
Less common causes of elevated calcium are chronic kidney failure, primary hyperparathyroidism, which is over-function of the parathyroid gland, poisoning with certain types of rodent bait and bone disease.
One cause of low blood calcium is malfunction of the parathyroid glands, which produce a hormone (PTH) that controls blood calcium levels. Animals poisoned with antifreeze may have very low blood calcium.
Carbon Dioxide (CO2) - measures a buffer system in the blood. A normal CO2 level keeps the blood acidity at the correct level.
Chloride – is the major anion found in the fluid outside of cells and in blood. An anion is the negatively charged part of certain substances.
Elevations in chloride may be seen in diarrhoea, certain kidney diseases and sometimes in over activity of the parathyroid glands.
Decreased chloride is normally lost in the urine, sweat and stomach secretions. Excessive loss can occur from heavy sweating, vomiting and adrenal gland and kidney disease.
Cholesterol – is the most common type of steroid in the body. Cholesterol is carried in the bloodstream as lipoproteins. Cholesterol can be increased in the bloodstream for many reasons in dogs.
Some of the diseases that cause elevated cholesterol are hypothyroidism, Cushing’s disease, diabetes and kidney diseases that cause protein to be lost in the urine. High cholesterol does not predispose dogs to heart and blood vessel disease as it does in people.
Creatinine Phosphatase (CK) – is a muscle enzyme.
Creatinine – is a waste product in the blood that results from the normal breakdown of muscle. Healthy kidneys filter creatinine from the blood. An elevation of creatinine is due to kidney disease or dehydration.
Both creatinine and Urea (BUN), increase in the bloodstream at the same time in patients with kidney disease. An elevation of Phosphorus with Creatinine and Urea (BUN) indicate a long standing kidney problem.
Electrolytes – are related to fluid balance in your cells. They are especially important if you become dehydrated or have kidney problems. Electrolytes include sodium, potassium, chloride, and bicarbonate.
Gamma Glutamyl Transpeptidase (GGT)) – is a liver enzyme. High level can indicate liver damage.
Globulin – measures the protein in antibodies produced by the immune system.
Glucose – is the sugar that is the chief source of energy. Glucose is considered a simple sugar. Found in the blood, it is the
main sugar that the body manufactures. High glucose levels in the blood indicate diabetes.
It may be mildly increased in dogs with Cushing’s disease. Glucose can temporarily increase
in the blood if the dog is excited by having a blood sample drawn. Low blood sugar occurs less commonly and can be a sign of pancreatic cancer or overwhelming infection (sepsis). Low blood
sugar can cause depression or seizures.
Lactic dehydrogenase (LDH) – is an enzyme that is elevated if kidney, skeletal muscles, liver or myocardium is injured.
NA/K Ratio – A low sodium potassium ratio can be a very important indicator for Addison’s Disease, although it is possible to have a normal sodium and potassium
values. Note: To confirm Addison’s disease you may require the ACTH Stimulation test.
Phosphate (Phosphorus in USA) – is an essential element in the diet and a major component of bone. Phosphorus in the bloodstream originates from
bones. Phosphorus is increased in the bloodstream in patients with chronic kidney disease. Like BUN and creatinine, phosphorus increases in these patients when about 75 percent of both kidneys
are damaged.
Please note: 'not usually significant if elevated in young, healthy, growing dogs'.
Potassium – affects several major organs including the heart. Potassium is increased in the bloodstream in the pet with acute kidney failure such as kidney failure
caused by antifreeze poisoning, in dogs with Addison’s disease and in animals with a ruptured or obstructed bladder. Potassium is lost from the body in vomit, diarrhoea and urine. Pets
that are not eating may have low blood potassium. Low blood potassium can cause the pet to feel weak.
Sedimentation Rate or Sed Rate – measures how quickly red blood cells settle in a tube of blood. A high sed rate indicates some type of inflammation.
Sodium – levels indicate your balance of salt and water. They also are a sign of the functioning of your kidneys and adrenal glands. Sodium may be slightly increased
in the blood if the patient is dehydrated although many dehydrated dogs have normal blood sodium. Low blood sodium is most commonly seen with Addison’s disease.
Total Protein (TP) – protein includes albumin and larger proteins called globulins. Included in the globulins are antibodies, which are protein molecules. Total protein
can be increased if the dog is dehydrated or if the pet’s immune system is being stimulated to produce large amounts of antibody. Total protein is decreased in the same situations which
reduce albumin or if the pet has an abnormal immune system and cannot produce antibodies.
Uric Acid – comes from the breakdown of DNA (genetic material in the cells), the kidneys normally remove it. High levels of uric acid are fairly common. Very high levels can
be caused when the kidneys are unable to remove uric acid from the blood or by leukaemia or lymphoma.