31
Reaction Sequence
Albumin (ALB)
Albumin forms the largest fraction of the total serum protein in the healthy animal. It is synthesized
solely by the liver, has a relatively low molecular weight, and plays an important role in the transport
of endogenous and exogenous compounds by binding with those compounds. Albumin also plays
a major role related to osmoregulation.
Principal Reasons for Performing the Test
To investigate causes of hypoalbuminemia: protein-losing nephropathy, protein-losing enteropathy,
as well as hepatic insufficiency (decreased production) and decreased absorption due to
malabsorption (gastrointestinal disease) or malnutrition. In addition, it is helpful in characterizing
the degree of dehydration with increases in serum albumin concentrations, and it is commonly
decreased with active inflammatory disease (negative acute phase reactant).
The test should not be performed in isolation because of its lack of specificity.
Most Common Abnormalities Indicated by the Test
Decreased albumin—inflammatory disease, protein-losing nephropathy and enteropathy, and
decreased production (hepatic insufficiency).
Increased albumin—dehydration.
Sample Type and Precautions
Remove plasma or serum promptly from the cells or clot. Hemolysis may occur if the sample is not
handled properly. Although dry-slide technology minimizes the interfering effect of mild-to-moderate
hemolysis, marked hemolysis will cause an increased albumin value.
Complementary Tests
Albumin concentration is usually determined in conjunction with the measurement of total protein
and other tests of renal and hepatic function. When albumin is measured with total protein, the total
globulins will be calculated automatically and given with the results.
Reaction Sequence
Alkaline Phosphatase (ALKP)
The enzyme alkaline phosphatase is found in many body tissues. Highest levels are found in the
kidney cortex, small intestinal mucosa, and osteoblasts. The enzyme is also present in the liver
primarily located on the bile canalicular; thus an increase in ALKP may indicate cholestasis.
In cats and horses, the half-life of hepatic alkaline phosphatase is very short for ALKP and even
shorter for other natural tissue sources of ALKP due to rapid renal excretion/metabolism. Sensitivity
of the test in cats and horses is low. Since the nonhepatic sources of ALKP have relatively short
half-lives compared to the hepatic source, a mild-to-modest increase in ALKP in these species can
be a specific indicator of cholestasis.
Appendices
