Hypochloremia in cats – prevalence and associated diseases

Summary

Objective: To describe the prevalence and possible causes of hypochloremia in the local hospital cat population. Material and methods: Retrospective study consisting of two parts. Data were collected from the local electronic medical records database using the search terms „chloride“ and „cats“ (part A), and „blood gas analysis“ and „cats“ (part B). The medical records of the hypochloremic cats were then reviewed to determine prior treatment or infusions and to identify major underlying disease processes. Part A included an age and gender matched non-hypochloremic control group, whereas in part B acid-base status was assessed. Results: Hypochloremia was detected in 367 (27%) of 1363 blood samples. The application of a correction formula to adjust for free water changes decreased the number of hypochloremic cats to 253 (19%). Only a minority had received glucocorticoids or loop diuretics and the prevalence of vomiting was 44%. Common associated disorders were gastrointestinal and respiratory diseases, as well as azotemia and diabetes mellitus. Polyuria/ polydipsia, dehydration, prednisolone or furosemide pretreatment, azotemia and diabetes mellitus increased, whereas fluid therapy and the diagnosis of neoplasia decreased the prevalence of hypochloremia. An inverse correlation was found between corrected chloride and standar dized base excess (r_s = –0.597, p = 0.001) as well as anion gap (r_s = –0.4, p = 0.026). 99% of the hypochloremic cats had derangements of acid-base balance. Conclusion: Hypochloremia is a common electrolyte disorder in the local cat population. The correction formula is ne cessary to adjust for changes in plasma osmolality. Although associated with metabolic alkalosis, most of the hypochloremic cats have a normal or decreased pH. The inverse correlation of chloride and anion gap als well as the high proportion of azotemic or diabetic animals support the concept of compensatory acidosis induced hypochlor emia. Clinical relevance: Hypochloremia should prompt the clinician to performe blood-gas analysis. Diabetes mellitus (especially ketoacidosis) and renal disease should be included in current algorithms for the evaluation of hypochloremic patients.

Zusammenfassung

Ziel war die Erfassung der Prävalenz und der möglichen Ursachen der Hypochlorämie in der lokalen Katzenpopulation. Material und Methoden: Die Datenerfassung erfolgte retrospektiv mit dem lokalen elektronischen Datenerfassungssystem und den Suchbegriffen „Chlorid“ und „Katzen“ (Teil A) bzw. „Blutgasanalyse“ und „Katzen“ (Teil B). Die Aufzeichnungen zu den hypochlorämischen Katzen wurden auf Vorbehandlungen sowie zugrundeliegende Erkrankungen untersucht. Teil A beinhaltete eine alters- und geschlechtangepasste Kontrollgruppe ohne Hypochlorämie. Ergebnisse: In 367 (27%) von 1363 Proben wurde eine Hypochlorämie diagnostiziert. Die Anwendung der Korrekturformel zur Berücksichtigung von Veränderungen des freien Wassers verminderte die Anzahl hypochlorämischer Katzen auf 253 (19%). Nur eine Minderheit war mit Glukokortikoiden oder Diuretika vortherapiert und die Prävalenz von Erbrechen lag bei 44%. Häufig assoziierte Erkrankungen waren gastrointestinaler und respiratorischer Natur, aber auch Azotämie und Diabetes mellitus. Die Prävalenz der Hypochlorämie erhöhte sich durch die Faktoren Polyurie/Polydipsie, Dehydratation, Vorbehandlungen (Prednisolon oder Furose-mid), Azotämie und Diabetes mellitus und verminderte sich durch Infusionstherapie und die Diagnose Neoplasie. Eine inverse Korrelation bestand zwischen Chlorid und dem standardisierten Basenüberschuss (r_s = –0,597, p = 0,001) wie auch mit der Anionenlücke (r_s = –0,4, p = 0,026). Veränderungen im Säure-Basen-Haushalt zeigten 99% der hypochlorämischen Katzen. Schlussfolgerung: Die Hypochlorämie stellt bei Katzen eine häufige Elektrolytveränderung dar. Die Anwendung der Korrekturformel ist wichtig, um eine auf Verdünnungseffekten beruhende Pseudohypochlorämie auszuschließen. Obwohl mit metabolischer Alkalose assoziiert, liegt bei den meisten dieser Patienten ein physiologischer oder erniedrigter pH-Wert vor. Die Ergebnisse unterstützen das Konzept der kompensatorischen Azidose-induzierten Hypochlorämie. Klinische Relevanz: Bei einer Hypochlorämie sollte eine Blutgasanalyse erfolgen. Diabetes mellitus (vor allem Ketoazidose) und Nierenversagen sollten in den Algorithmus zur Abklärung einer Hypochlorämie integriert werden.

Keywords

Chloride - metabolic compensation - electrolyte disorder - algorithm - diabetes mellitus - renal failure

Schlüsselwörter

Chlorid - metabolische Kompen sation - Elektrolytentgleisung - Algorithmus - Diabetes mellitus - Nierenversagen

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