Diagnostic efficacy of the leukogram and the chemiluminometric ACTH measurement to diagnose canine hypoadrenocorticism

F. K. Zeugswetter; I. Schwendenwein

doi:10.1055/s-0038-1623768

Tierärztliche Praxis Ausgabe K: Kleintiere / Heimtiere, Inhaltsverzeichnis

Tierarztl Prax Ausg K Kleintiere Heimtiere 2014; 42(04): 223-230
DOI: 10.1055/s-0038-1623768

Original Article

Schattauer GmbH

Diagnostic efficacy of the leukogram and the chemiluminometric ACTH measurement to diagnose canine hypoadrenocorticism

Diagnostische Effizienz des Leukogramms und der endogenen ACTH-Konzentration zur Diagnose des Hypoadrenokortizismus beim Hund

F. K. Zeugswetter

¹Department of Companion Animals and Horses, University of Veterinary Medicine Vienna, Vienna, Austria

,

I. Schwendenwein

¹Department of Companion Animals and Horses, University of Veterinary Medicine Vienna, Vienna, Austria

²Department of Pathobiology, University of Veterinary Medicine Vienna, Vienna, Austria

› Institutsangaben

Abstract

Summary

Background and objective: The gold standard in the diagnosis of canine hypoadrenocorticism (HA) is the adrenocorticotropin (ACTH) response test. As synthetic ACTH (tetracosactide [Synacthen®]) is currently not available in the European Union, the evaluation of other diagnostic tests seemed warranted. The diagnostic efficacy of electrolytes, the leukogram and endogenous ACTH concentrations to diagnose HA was investigated. Material and methods: The medical records of 145 dogs with clinical signs suspect for spontaneous HA were included in a retrospective study. HA was diagnosed (n = 38) or ruled out (n = 84) by using an ACTH response test. In 23 patients HA was excluded by basal cortisol measurement. The diagnostic performance of various variables was assessed based on receiver operating characteristic (ROC) curves and by calculating differential positive rates. A decision tree (IBM SPSS Decision Trees 20, IBM Corporation) was constructed with the variables neutrophil to lymphocyte ratio (N/LR) and sodium to potassium ratio (Na/KR) to illustrate the diagnostic efficacy of the respective test results. Results: The best single variables to diagnose HA were the endogenous ACTH concentration (area under the ROC curve [ROC AUC] 0.97; cutoff > 50 pmol/l: sensitivity 96%, specificity 100%) and the Na/KR (ROC AUC 0.905; cutoff ≤ 22: sensitivity 92%, specificity 91%). The diagnostic performance of various variables of the leukogram was poor to moderate (ROC AUC 0.625–0.828). 68% of dogs with HA had a Na/KR ≤ 22 and a N/LR ≤ 2.3, a combination not observed in dogs with non-adrenal diseases. Conclusion and clinical relevance: As secondary HA is very rare, endogenous ACTH measurement is a very good alternative to the traditional ACTH response test. Data also suggest that the combination of a Na/KR ≤ 22 and a N/LR ≤ 2.3 is highly specific and can be used to rule in HA.

Zusammenfassung

Gegenstand und Ziel: Der ACTH-Stimulationstest ist der Goldstandard zur Diagnose des kaninen Hypoadrenokortizismus (HA). Da das dafür benötigte synthetische ACTH Tetracosactid (Synacthen®) derzeit in der Europäischen Union nicht erhältlich ist, wurde in dieser Studie die diagnostische Effizienz der Elektrolyte, des Leukogramms sowie der ACTH-Konzentration zur alternativen Diagnosesicherung des HA evaluiert. Material und Methode: Die Befunde von 145 Hunden mit für HA typischen klinischen Symptomen wurden retrospektiv ausgewertet. Das Vorliegen eines HA wurde bei 38 Patienten mittels ACTH-Stimulationstest bestätigt und bei 107 Tieren mittels ACTH-Stimulationstest (n = 84) oder aufgrund eines Kortisolbasalwerts > 55 nmol/l (n = 23) ausgeschlossen. Das Leukogramm wurde mit dem System ADVIA 120 erstellt und nach einem Algorithmus mikroskopisch kontrolliert. Zur ACTH-Messung diente ein validierter chemiluminometrischer Assay. Die Beurteilung der diagnostischen Effizienz der verschiedenen Labormesswerte erfolgte mithilfe von Receiver-Operating-Characteristic(ROC)-Kurven und Berechnung der Differential Positive Rate. Ergebnisse: Die besten alternativen Einzeltests zur Diagnose des HA waren die endogene ACTH-Konzentration (Fläche unter der ROC-Kurve [ROC AUC] 0,97; Cutoff-Wert > 50 pmol/l: Sensitivität 96%, Spezifität 100%) und der Natrium-Kalium-Quotient (Na/KR, ROC AUC 0,905; Cutoff-Wert ≤ 22: Sensitivität 92%, Spezifität 91%). Für das weiße Blutbild ergab sich eine moderate diagnostische Aussagekraft (ROC AUC 0,625–0,828). 68% der Hunde mit HA zeigten einen Neutrophilen-Lymphozyten-Quotienten ≤ 2,3 und einen Natrium-Kalium-Quotienten ≤ 22. Diese Kombination trat bei keinem Patienten auf, der nicht an HA litt. Schlussfolgerung und klinische Relevanz: Aufgrund der Seltenheit des sekundären HA stellt die Messung der endogenen ACTH-Konzentration eine sensitive und spezifische Alternative zum ACTH-Stimulationstest dar. Auch ein Neutrophilen-Lymphozyten-Quotient ≤ 2,3 in Kombination mit einem Natrium-Kalium-Quotienten ≤ 22 spricht für eine Unterfunktion der Nebennierenrinde.

Key words

White blood cell count - neutrophil to lymphocyte ratio - sodium to potassium ratio - adrenocorticotropin - Addison’s disease - dog

Schlüsselwörter

Weißes Blutbild - Neutrophilen-Lymphozyten-Quotient - Natrium-Kalium-Quotient - adrenokortikotropes Hormon - Morbus Addison - Hund

Volltext

Referenzen

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