Urate (uric acid) measurement is commonly used in human medicine for the diagnosis
and treatment of gout, rheumatoid arthritis and other conditions that can alter purine
metabolism. Urate is the end point of purine metabolism in humans, but most mammalian
species are able to further metabolize urate to allantoin resulting in lower plasma urate
values which have little diagnostic value in general toxicity studies. Lactate
dehydrogenase activity is highly variable and lacks specificity as an indicator of major
organ toxicity in animal species (Evans, 1991). The analytical requirements and testing
performance for plasma ornithine decarboxylase (Carakostas, 1988) and to a lesser extent
ornithine carbamoyl transferase (Carakostas et al., 1986) make these tests impractical for
use as routine screening tests in non-clinical toxicity and safety studies. Succinate
dehydrogenase is rarely measured in toxicity studies and few data have been published on
its utility. Similarly, there is currently very little scientific information available
concerning the effects of toxicity on serum protein fractions in laboratory animal species
to support meaningful interpretation of electrophoretic separation of serum proteins for
many of the samples taken routinely during the study.