Referenzbereiche von Insulin, insulinähnlichem Wachstumsfaktor 1 (IGF-1) und adrenokortikotropem Hormon bei Ponys

Zusammenfassung

Ziel dieser Arbeit war, den Einsatz des Automaten IMMULITE 2000® mit einem immunometrischen Chemolumineszenz-Assay für die Bestimmung von adrenokortikotropem Hormon (ACTH), Insulin und Insulinwachstumsfaktor 1 (IGF-1) zu prüfen und entsprechende Referenzbereiche für Ponys zu berechnen. Material und Methoden: Nachmittags gewonnene Blutproben von 130 Ponys im Alter von 3–32 Jahren wurden auf Insulin, IGF-1 und ACTH untersucht. Die Referenzbereiche wurden nach der Richtlinie EP28-A3C der International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) aus dem Jahr 2010 berechnet. Ergebnisse: Die Präzision für die Messungen an einem Tag lag für Insulin im Mittel bei 3,28%, für IGF-1 bei 1,84% und für ACTH bei 3,35%. Die Tag-zu-Tag-Präzision (Insulin: 3,45%; IGF-1: 2,89%; ACTH: 9,77%) wurde an drei aufeinanderfolgenden Tagen gemessen, wobei die Lagerung der Proben bei 4 °C erfolgte. Es zeigte sich kein signifikanter Verlust der Insulinaktivität bzw. der Konzentrationen von ACTH und IGF-1. Für Insulin und IGF-1 ergaben sich altersunabhängige Referenzbereiche (Insulin: 2,0–21,2 mU/l; IGF-1: 50,2–357,2 μg/l). Dagegen wurde für ACTH ein altersabhängiger Referenzbereich er - mittelt, der bei Ponys im Alter von 3–12 Jahren signifikant niedriger war (4,2–19,8 pg/ml) als bei Ponys im Alter von 13–32 Jahren (5,0–22,6 pg/ml). Schlussfolgerung: Das verwendete Analyseverfahren eignet sich für die Untersuchung von Serumproben von Ponys auf ACTH, IGF-1 und Insulin, doch wird der Einsatz bei der Insulinmessung durch die untere Nachweisgrenze von 2,0 mU/l limitiert. Klinische Relevanz: Die berechneten Referenzbereiche für Insulin und ACTH sind hilfreich für die Diagnostik und Verlaufskontrolle des equinen metabolischen Syndroms und der Pituitary Pars Intermedia Dysfunction (PPID).

Summary

Objectives: The aim of this study was to validate a chemiluminescence immunometric assay using the IMMULITE 2000^® for the determination of adrenocorticotropic hormone (ACTH), insulin and insulin-like growth factor-1 (IGF-1) from which reference ranges were calculated for ponies. Material and methods: Blood samples of 130 po - nies aged 3–32 years were collected in the afternoon. The reference ranges were calculated according to the Guideline EP28-A3C of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) from 2010. Results: The determined intraday precision for insulin was 3.28%, for ACTH 3.35% and for IGF-1 1.84%. The interday precision (insulin: 3.45%; IGF-1: 2.89%; ACTH: 9.77%) was determined on three consecutive days, where the samples were stored at 4 °C. There was no significant loss of insulin activity nor of ACTH or IGF-1 concentration during this time. The reference ranges of insulin and IGF-1 (2.0–21.2 mU/l and 50.2–357.2 mU/l, respectively) were age independent, whereas for ACTH, an age-dependent reference range was established. Ponies aged 3–12 years had a significantly lower reference range (4.2–19.8 pg/ml) than ponies aged 13–32 years (5.0–22.6 pg/ml). Conclusion: The method used is suitable for the deter mination of ACTH, IGF-1 and insulin in serum of ponies, but the lowest detection limit for insulin is 2.0 mU/l. Clinical relevance: The calculated reference ranges of insulin and ACTH are helpful for the diag nosis and clinical monitoring of equine metabolic syndrome and pituitary pars intermedia dysfunction (PPID).

Schlüsselwörter

Insulin-Units - IGF-1 - ACTH - equines metabolisches Syndrom - PPID

Keywords

Insulin units - IGF-1 - ACTH - equine metabolic syndrome - PPID

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