Assessment of corticosteroid-induced alkaline phosphatase isoenzyme as a screening test for hyperadrenocorticism in dogs.
Quantitative determination of the corticosteroid-induced isoenzyme of alkaline phosphatase (CAP) was evaluated as a screening test for hyperadrenocorticism (HAC) in dogs. A series of 40 dogs with HAC (CAP range, 96 to 14,872 U/L), 30 clinically normal dogs (CAP range, 0 to 38 U/L), and 80 dogs with various diseases (non-HAC) and without history of exogenous glucocorticoid exposure for a minimum of 60 days (CAP range, 0 to 1163 U/L) were used to evaluate the test. Sensitivity and specificity of CAP was calculated at various cutoff points for absolute CAP activity and for CAP activity expressed as a percentage of total alkaline phosphatase activity. A cutoff point of 90 U/L was selected as optimal for use of this assay as a screening test for HAC. A prevalence survey then was done of all canine serum samples submitted to our diagnostic laboratory over a 3-month period, to calculate the predictive values of a positive and a negative test result in a clinical population and to determine the relative frequency and magnitude of CAP activity in dogs that had received glucocorticoids. The predictive values of a positive and a negative test result at the 90 U/L cutoff value were 21.43% (95% confidence limits, 8.3 to 40.95%) and 100% (95% confidence limit > 96%), respectively. It was concluded that CAP isoenzyme activity, determined by routine biochemical analysis by an automated levamisole-inhibition assay, could function as a screening test for HAC; however, the predictive value of a positive test result was too low to recommend the assay as a diagnostic test.(ABSTRACT TRUNCATED AT 250 WORDS)
Solter
P F
PF
Department of Pathobiology, College of Veterinary Medicine, University of Illinois, Urbana 61801.
Hoffmann
W E
WE
Hungerford
L L
LL
Peterson
M E
ME
Dorner
J L
JL
D000308:Adrenocortical Hyperfunction / Q000175:diagnosis / Q000662:veterinary*; D000469:Alkaline Phosphatase / Q000097:blood*; D000818:Animals; D004283:Dog Diseases / Q000175:diagnosis* / Q000188:drug therapy; D004285:Dogs; D005069:Evaluation Studies as Topic; D005938:Glucocorticoids / Q000494:pharmacology* / Q000627:therapeutic use; D007527:Isoenzymes / Q000097:blood*; D012680:Sensitivity and Specificity
D005938:Glucocorticoids; D007527:Isoenzymes; D000469:Alkaline Phosphatase