Chemistry tests can be grouped together on the basis of body system or physiologic process. Grouping tests into common parameters is the best way to interpret chemistry data as it enables pattern recognition. Patterns of change
within and among these groups can provide useful diagnostic information about
disease involvement of various organ systems. Grouping tests together can also help you select certain tests to identify disease processes in certain body systems. Test selection is important if cost is a factor in laboratory testing.
The following is one way of grouping routine chemistry tests:
- Electrolytes: Sodium, potassium and chloride.
- Acid/base parameters: Bicarbonate, anion gap.
Note: Acid base status is dependent on electrolytes, so these should be interpreted together.
- Minerals: Calcium, phosphate and magnesium.
Note: These are often influenced by kidney function, so kidney parameters should be evaluated concurrently. Also, many bovine practitioners order mineral and electrolyte panels.
- Protein parameters: Total protein, albumin, globulin, A/G ratio.
- Kidney parameters: Urea nitrogen, creatinine.
Note: Urine specific gravity should be concurrently evaluated when assessing renal function, especially on initial presentation of the animal. In addition, kidney function affects proteins, minerals, electrolytes and acid-base balance, as well as hematopoiesis. Can you think of how renal disease alters hematopoiesis?
- Liver parameters:
Hepatocellular leakage enzymes: Alanine aminotransferase (ALT), aspartate aminotransferase (AST), sorbitol dehydrogenase (SDH), lactate dehydrogenase (LDH).
Cholestatic enzymes: Alkaline phosphatase (AP), gamma glutamyl transferase (GGT).
Liver function tests: Total bilirubin, direct bilirubin, indirect bilirubin, bile acids, ammonia.
- Pancreatic parameters: Amylase, lipase, trypsin-like immunoreactivity.
- Carbohydrate parameters: Glucose, fructosamine, glycosylated hemoglobin.
- Lipid parameters: Cholesterol, triglycerides.
Note: Lipid metabolism is altered by disease processes affecting the pancreas and glucose homeostasis.
- Muscle parameters: Creatine kinase (CK), AST, ALT, LDH.
- Iron parameters: Serum/plasma iron, total iron binding capacity (TIBC), % iron saturation of transferrin.
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