Comparison of immunofluorescence and chemiluminescence assays for measuring ACTH in equine plasma
| Autor: | Pat Harris, Tegan A. McGilvray, Nicola J. Menzies-Gow, E. J. Knowles |
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| Rok vydání: | 2020 |
| Předmět: |
endocrine system
medicine.medical_specialty Luminescence Fluorescent Antibody Technique Stimulation Immunofluorescence law.invention Basal (phylogenetics) Adrenocorticotropic Hormone law biology.animal Internal medicine medicine Pituitary pars intermedia dysfunction Animals Horses Thyrotropin-Releasing Hormone Chemiluminescence biology medicine.diagnostic_test Chemistry Pony Horse General Medicine Endocrinology Luminescent Measurements Horse Diseases hormones hormone substitutes and hormone antagonists Hormone |
| Zdroj: | Equine Veterinary Journal. 52:709-714 |
| ISSN: | 2042-3306 0425-1644 |
| DOI: | 10.1111/evj.13227 |
| Popis: | The chemiluminescence (CL) and immunofluorescence (IF) assays yield different results for basal adrenocorticotropin hormone concentrations [ACTH] in pony plasma. It is unclear whether this difference also occurs in basal samples from horses or samples from ponies following thyrotropin-releasing hormone (TRH) stimulation.To compare the results of [ACTH] analysis by CL and IF methods in basal samples from horses and pony samples following TRH stimulation.Method comparison.Plasma [ACTH] was measured concurrently using CL and IF methods in 12 ponies (basal and post-TRH stimulation) in November and basal samples from horses (n = 45; November and May).CL and IF methods yielded different results (P .01). The median difference (CL-IF) (95% CI) for ponies was 5.9 (0.1-7.5) pg/mL at baseline and 227.9 (61-1001) pg/mL post TRH; and horses 1.9 (1.1-5.4) pg/mL in November and 9.4 (8.2-11.5) pg/mL in May, at baseline. Correlation was good in ponies at baseline (R = 0.80, P = .003) but not post-TRH, and good in horses in November and May (R = 0.68 and 0.71, P .001). Bland-Altman analysis demonstrated moderate bias and wide 95% limits of agreement (95% LOA) in ponies at baseline (bias 5.5 pg/mL; 95% LOA -9.9 to 20.9 pg/mL) and horses in May (bias 10.6 pg/mL; 95% LOA -9 to 30.3 pg/mL) and very large bias and wide 95% LOA in ponies post-TRH (bias 477 pg/mL; 95% LOA -633 to 1587 pg/mL). Using CL cut-offs of29 and110 pg/mL, agreement was moderate (ƙ = 0.67) and very good (ƙ = 0.82) for binary classification of PPID in ponies at baseline and post-TRH; and good (ƙ = 0.73) for horses in November, but poor (ƙ = 0.40) in May.Limited numbers of horses with [ACTH] above threshold values.The assays yielded different absolute values, particularly in post-TRH samples from ponies, suggesting TRH stimulates secretion of cross-reacting peptides other than ACTH. Agreement for binary classification for PPID was moderate to good, except in basal samples from horses in May. |
| Databáze: | OpenAIRE |
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