Evaluation verschiedener Prädiktoren einer chronischen Nierenerkrankung bei hyperthyreoten Katzen nach einer Radiojodtherapie – eine Pilotstudie

Zusammenfassung

Gegenstand und Ziel

Bisher gibt es keinen geeigneten Parameter für die Vorhersage des Auftretens einer azotämischen chronischen Nierenerkrankung (CNE) nach der Behandlung einer Hyperthyreose bei Katzen. Ziel dieser Studie war es, klinische und labordiagnostische Marker sowie die sonografisch gemessene Nierenrindendicke als Prädiktoren einer azotämischen CNE nach einer Radiojodtherapie (RJT) zu untersuchen.

Material und Methoden

Katzen, vorgestellt für eine RJT (April 2021–April 2022), wurden prospektiv eingeschlossen. Katzen mit einer Azotämie (Kreatinin≥140 µmol/L) und/oder einer pathologischen Nierenmorphologie wurden ausgeschlossen. Nach der RJT wurden die Katzen über 6–12 Monate kontrolliert (Messung des Gesamtthyroxins [TT4], des Thyreoidea-stimulierenden Hormons und des Kreatinins). Katzen mit persistierender Hyperthyreose und Katzen mit einem Follow up<6 Monaten wurden von der statistischen Auswertung ausgeschlossen, da keine eindeutige Aussage bezüglich ihrer Schilddrüsen- und Nierenfunktion getroffen werden konnte. Folgende vor der RJT erhobene Parameter wurden zwischen Katzen, die nach der RJT eine azotämische CNE entwickelten, und solchen, die nicht-azotämisch blieben, verglichen: Alter, Gewicht, Dauer seit der Diagnosestellung der Hyperthyreose bis zu der RJT, Blutdruck, Hämatokrit, Konzentration von Kreatinin, Harnstoff, Kalium, Phosphat, TT4 und Symmetrisches Dimethylarginin, urinspezifisches Gewicht, Protein/Kreatinin-Quotient im Urin sowie sonografisch gemessene Nierenrindendicke.

Ergebnisse

Es wurden 51 Katzen eingeschlossen, 29/51 gingen in die statistische Auswertung ein (11/29 wurden nach der RJT euthyreot und 18/29 wurden hypothyreot). Es gab keinen Unterschied in der Frequenz der Azotämie zwischen eu- und hypothyreoten Katzen (5/11 vs. 6/18, p=0,7). Keiner der untersuchten klinischen, labordiagnostischen sowie morphologischen Marker erwies sich als prädiktiv für die Entwicklung einer azotämischen CNE nach einer RJT.

Schlussfolgerung und klinische Relevanz

Keiner der untersuchten Parameter war prädiktiv für die Entwicklung einer azotämischen CNE bei hyperthyreoten Katzen nach einer RJT. Aufgrund der kleinen Studienpopulation erscheinen zukünftige größere Studien, vor allem hinsichtlich morphologischer Parameter, sinnvoll.

Abstract

Objective

Currently, no suitable parameter to predict the occurrence of azotaemic chronic kidney disease (CKD) after hyperthyroidism treatment in cats exists. The aim of this study was to evaluate various clinical and laboratory parameters as well as renal cortical thickness (assessed by ultrasound) as predictors of azotaemic CKD after radioiodine therapy (RAIT).

Material and methods

Cats presented for RAIT (April 2021–April 2022) were prospectively enrolled. Cats with azotaemia (creatinine≥140 µmol/L) and cats with pathological renal morphology were excluded. After RAIT, cats were followed for 6–12 months (measurement of total thyroxine [TT4], thyroid-stimulating hormone and creatinine). Cats with persistent hyperthyroidism and cats with a follow-up<6 months were excluded from the statistical analysis, as their thyroid and kidney function could not be sufficiently evaluated. Following parameters obtained prior RAIT were compared between cats that developed azotaemic CKD following RAIT and those that did not: age, weight, duration since the diagnosis of hyperthyroidism and RAIT, blood pressure, haematocrit, concentration of creatinine, urea, potassium, phosphate, TT4 and symmetrical dimethylarginine, urine-specific gravity, urine protein/creatinine ratio and sonographically assessed renal cortical thickness.

Results

51 cats were enrolled; 29/51 were included in the statistical analysis (11/29 became euthyroid and 18/29 became hypothyroid post RAIT). There was no difference in the frequency of azotaemia between euthyroid and hypothyroid cats (5/11 vs. 6/18, p=0.7). None of the clinical, laboratory and morphological markers proved to be predictive of the development of azotaemic CKD following RAIT.

Conclusion and clinical relevance

None of the investigated parameters was predictive of the development of azotaemic CKD in hyperthyroid cats after RAIT. Due to the small study population, future larger studies should be undertaken, especially to assess morphological markers.

Schlüsselwörter

Nierenrindendicke - Ultraschall - Thyroxin - Thyreoidea-stimulierendes Hormon - iatrogene Hypothyreose

Keywords

Renal cortical thickness - ultrasound - thyroxine - thyroid-stimulating hormone - iatrogenic hypothyroidism

Publication History

Article published online:
02 September 2025

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