Clinical Biochemistry of Domestic Animals (Sixth Edition) - UMK ...

370
Chapter | 12 Diagnostic Enzymology of Domestic Animals
In long-distance sled dog races, there are marked interindividual
variations with activity ranging from unchanged
to more than 13-fold increase. However, there is minimal
increase in serum CK activity following exercise in
untrained beagle dogs ( Chanoit et al. , 2002 ). In horses, it
has been concluded through kinetic studies that the amount,
in grams, of striated muscle damaged is negligible following
exercise ( Volfinger et al. , 1994 ). It has been reported that
increases tend to occur more frequently in fillies, younger
animals, and untrained horses ( Harris et al. , 1998 ).
In all species, CK has the advantage over serum aspartate
aminotransferase in being specific for muscle injury
and not affected by hepatocellular injury. The short halflife
of the enzyme may tend to reduce the diagnostic sensitivity
of the test, but it also offers an effective means of
monitoring response to therapy.
K . Other Enzymes
As mentioned in the introduction, numerous other enzymes
have been investigated for use in diagnosis and prognosis
of disease and organ dysfunction in nonhuman animals.
Some of these have been dropped altogether or receive
limited use, such as lactic acid dehydrogenase, 5 nucleotidase,
glutathione S-transferase, leucine aminopeptidase,
arginase, aldolase, and acid phosphatase, among others.
The reasons for their limited use vary but include relatively
poor diagnostic accuracy, diagnostic redundancy with
already established tests, and a lack of readily available
test kits. For example, serum lactic acid dehydrogenase
(LDH) activity originates from several tissues including
liver, skeletal muscle, heart muscle, and erythrocytes. This
resulting decreased test sensitivity and specificity limits
the diagnostic accuracy of serum LDH activity. Although
LDH isoenzyme analysis may improve tissue specificity,
the tests are relatively time consuming, expensive, and still
only provide a subjective assessment of the contribution of
each organ to the total serum activity. In addition, the test
does not offer a substantial improvement over assays to
other enzymes such as alanine aminotransferase or creatine
kinase. A few laboratories still offer 5 nucleotidase, but it
provides much of the same information as ALP and perhaps
has lost favor as a result. Arginase is highly specific
for injury to hepatocytes but suffers from a short half-life
and is not readily available for autoanalyzers.
V . FUTURE OF SERUM ENZYMOLOGY
Although the number of studies investigating enzyme activity
assays for diagnostic purposes has decreased since the
1990s, they are still of immense importance to diagnostic
medicine. The currently increasing interest in identifying
protein and peptide markers of organ injury or dysfunction
will require immunoassays to determine their concentrations
in serum. This is often problematic to veterinarians, as
appropriate antibodies to these markers in domestic animals
are frequently unavailable. The divergence of human
biomarker research away from classical serum enzymology
has the unintended consequence of limiting the universality
of new biomarker application across species. Although this
continues to be a deterrent, there is increased interest in the
development and utilization of immunoassays in veterinary
medicine as evidenced by the assays for trypsin-like immunoreactivity
and pancreatic lipase immunoreactivity in
dogs and cats, as well as immunoassays for nonenzymatic
proteins, such as the natruretic peptides and troponins.
Problems regarding the availability of immunoassays and
long turnaround time from submission to obtaining laboratory
results are increasingly being addressed. For example,
the development of automated analyzers for immunoassays
has allowed test results to be available on the same day as
sample submission. Canine TLI is available on the Immulite
system from Diagnostic Products Corporation, and more
are expected in the future. The fields of serum enzymology
and serum protein markers have merged in human medicine
as evidenced by the topic section “ Proteomics and Protein
Markers ” in the table of contents of the journal Clinical
Chemistry. The development of this merger in nonhuman
animal medicine is almost certain to happen.
REFERENCES
Abraham , G. , Gottschalk , J. , and Ungemach , F. R. ( 2005 ). Evidence
of ototopical glucocorticoid-induced decrease of hypothalamicpituitary-adrenal
axis response and liver function . Endocrinology
146 , 3163 – 3171 .
Aktas , M. , Auguste , D. , Concordet , D. , Vinclair , P. , Lefebvre , H. ,
Toutain , P. L. , and Braun , J. P. ( 1994 ). Creatine kinase in dog plasma:
preanalytical factors of variation, reference values and diagnostic
significance . Res. Vet. Sci. 56 , 30 – 36 .
Aktas , M. , Auguste , D. , Lefebvre , H. P. , Toutain , P. L. , and Braun , J. P.
( 1993 ). Creatine kinase in the dog: a review . Vet. Res. Commun. 17 ,
353 – 369 .
Aktas , M. , Lefebve , H. P. , Toutain , P. L. , and Braun , J. P. ( 1995 ).
Disposition of creatine kinase activity in dog plasma following intravenous
and intramuscular injection of skeletal muscle homogenates .
J. Vet. Pharmacol. Ther. 18 , 1 – 6 .
Allen , L. C. V. , Allen , M. J. , Greur , G. J. , Hoffmann , W. E. , and
Richardson , D. C. ( 2000 ). A comparison of two techniques for the
determination of serum bone-specific alkaline phosphatase activity in
dogs . Res. Vet. Sci. 68 , 231 – 235 .
Allen , M. J. , Hoffmann , W. E. , Richardson , D. C. , and Breur , G. J. ( 1998 ).
Serum markers of bone metabolism in the dog . Am. J. Vet. Res. 59 ,
250 – 254 .
Anderson , H. C. , Sipe , J. B. , Hessle , L. , Dhanyamraju , R. , Atti , E. ,
Camacho , N. P. , and Millan , J. L. ( 2004 ). Impaired calcification
around matrix vesicules of growth plate and bone in alkaline
phosphatase -deficient mice . Am. J. Path . 164 , 841 – 847 .
Archer , F. J. , and Taylor , S. M. ( 1996 ). Alkaline phosphatase bone isoenzyme
and osteocalcin in the serum of hyperthyroid cats . Can. Vet. J.
37 , 735 – 739 .