Blood (Serum) Chemistry

Description: The serum chemistry profile is one of the most important initial tests that is commonly performed on sick or aging animals. A blood sample is collected from the patient. The blood is then separated into a cell layer and serum layer by spinning the sample at high speeds in a machine called a centrifuge. The serum layer is drawn off and a variety of compounds are then measured. These measurements aid the veterinarian in assessing the function of various organs and body systems.

Diagnostic Value: High. Sometimes a specific diagnosis may be made on the basis of a blood chemistry profile alone. More often than not, however, the profile provides information on a variety of body organs and systems, giving the doctor an indication of where a problem might be located. The profile can be extremely helpful in determining which of the many other diagnostic tests might be beneficial.

Risks to Patient:
Very low, provided that the blood is collected under sterile conditions by a trained professional.

Relative Cost: Low.

Normal Ranges: The following is a list of the normal ranges in cats for some of the major parameters on a chemistry profile:

Glucose: 67-124 mg/dl
Blood Urea Nitrogen (BUN): 15-32 mg/dl
Creatinine: 0.6-2.0 mg/dl
Calcium: 8.5-11.8 mg/dl
Phosphorus: 3.3-7.2 mg/dl
Total protein: 5.9-8.1 g/dl
Albumin: 2.3-3.9 g/dl
Cholesterol: 60-220 mg/dl
Alkaline Phosphatase (ALP): 10-150 IU/L
Alanine Aminotransferase (ALT): 30-100 IU/L
Aspartate Aminotransferase (AST): 14-38 IU/L
Creatine Phosphokinase (CPK): 60-300 IU/L
Chloride: 112-129 mEq/L
Potassium: 3.7-5.4 mEq/L
Sodium: 146-160 mEq/L

Interpretation of Results:

  • Glucose - This is a measurement of the blood sugar level.
  1. High glucose levels can occur just after a meal, during stressful situations, and with the use of certain drugs. The measurement of glucose is important in the diagnosis of diabetes mellitus.
  2. Low glucose levels can occur when the animal does not eat, has liver or hormonal problems, or when there is a severe bacterial infection in the bloodstream. Too much insulin will also cause low levels of glucose.
  • Blood Urea Nitrogen (BUN) - Urea, which is normally excreted by the kidney, is a by-product of protein metabolism.
  1. High levels of BUN may be the result of a high protein diet, dehydration, ulcers in the digestive tract, kidney disease, or blockage of the normal flow of urine (from a crystal or mucus plug, for example).
  2. Low BUN levels can result from a low protein diet or liver disease.
  • Calcium - This mineral is normally found in the body and is important for normal muscle and heart function.
  1. High calcium levels may be found in young, growing animals, with some types of cancer, bone disease, and parathyroid problems. A variety of other conditions may also cause an elevated calcium level.
  2. Low calcium levels can occur with dietary insufficiencies, parathyroid problems, intestinal problems, pancreatic disease, kidney failure, and antifreeze (ethylene glycol) poisoning. Other causes also exist.
  • Total Protein - Several protein types circulate in the bloodstream. These protein types can be measured all together or may be separated out and measured one at a time. On a routine blood chemistry profile, total protein is measured as the total of all proteins together. Albumin, the most abundant protein type, is usually measured separately.
  1. High protein levels may result from dehydration, inflammation, some cancers, and infections.
  2. Low protein levels can occur in situations of malnutrition, intestine absorption problems, blood loss, and kidney or liver disease.
  • Cholesterol
  1. High cholesterol levels can be associated with high-fat diets, diabetes mellitus, pancreatitis, Cushing’s disease, liver disease, and kidney problems.
  2. Low cholesterol levels may occur with low-fat diets, liver failure, digestive and absorption problems, pancreatic disease, and with some types of therapy for seizures.
  • Creatine Phosphokinase (CPK) - This is an enzyme found in muscle cells.
  1. High CK levels can occur in situations where muscles of the body are damaged, diseased, or inflamed. This can even occur with heart muscle problems.
  • Alkaline Phosphatase (ALP) - This is an enzyme found in liver and bone cells.
  1. High ALP levels may indicate a liver problem, some cancers, and increased bone growth or destruction. ALP levels can also be elevated in cases where steroids are administered or in Cushing’s disease where natural steroids are elevated. High levels of ALP are normal in young, fast growing kittens.
  • Alanine Aminotransferase (ALT) - This is another enzyme found in liver cells.
  1. High ALT levels occur when the liver is damaged. This damage can occur because of toxins, not enough oxygen, inflammation, metabolic disorders, certain infections, and other diseases.
  • Aspartate Aminotransferase (AST) - This is another enzyme produced by a variety of tissues. Concentrations tend to be highest in muscle and liver cells.
  1. High AST levels occur most often when the muscles and/or the liver are damaged. This damage can occur because of toxins, lack of oxygen, inflammation, metabolic disorders, and other diseases.
  • Chloride - This is a negatively-charged electrolyte (dissolved salt).
  1. High levels of chloride can occur with dehydration, fluid therapy, and acidosis (where the pH of the body is abnormally low). Some drugs such as phenobarbital can also cause elevated chloride levels.
  2. Low levels may be the result of vomiting, especially right after eating. Treatment with certain drugs (diuretics such as furosemide) can also cause low chloride levels.
  • Potassium - This is an electrolyte with a positive charge.
  1. High levels are associated with acidosis (where the pH of the body is abnormally low), severe kidney disease (during certain phases), rupture of the urinary bladder, and with some treatments and syndromes.
  2. Low levels are seen with chronic vomiting and diarrhea, liver disease, Cushing’s disease, certain phases of kidney disease, and the administration of some drugs.
  • Sodium- This is also another electrolyte with a positive charge.
  1. High sodium levels may accompany vomiting, diarrhea, dehydration, a high salt diet, Cushing’s disease, chronic kidney disease, some severe infections, and diabetes insipidus.
  2. Low sodium occurs with vomiting, diarrhea, fluid therapy, kidney problems, and congestive heart failure.
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