Validation of a point-of-care assay to diagnose PPID using ACTH and CLIP

A point-of-care (POC) immunoassay that can quantify ACTH and CLIP concurrently in a single equine plasma sample and report a composite “eACTH” measurement (POC-eACTH) was recently developed. It is commercially available in North America and Europe at present as TRUFORMA eACTH made by Zomedica Inc. This is a research study of the accuracy of this product. It appears to be useful.
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Validation of a point-of-care assay for simultaneous quantification of equine adrenocorticotropic hormone and corticotropin-like intermediate peptide
J Vet Intern Med. 2026 Sep 1;40(5):aalag253. doi: 10.1093/jvimsj/aalag253.
Authors
Kelsey A Hart 1 , Londa J Berghaus 1 , Ian Harmon 2
Affiliations

1 Department of Large Animal Medicine, University of Georgia College of Veterinary Medicine, Athens, GA 30602, United States.
2 Zomedica®, Inc; Plymouth, MN, United States.

PMID: 42858361
DOI: 10.1093/jvimsj/aalag253

Abstract

Background: Plasma adrenocorticotropic hormone (ACTH) concentrations are used to diagnose equine pituitary pars intermedia dysfunction (PPID). The reference chemiluminescent immunoassay for immunoreactive ACTH (iACTH) cross-reacts with corticotropin-like intermediate peptide (CLIP), which is also abnormally high in PPID.

Hypothesis/objectives: To compare the performance of a novel point-of-care (POC) immunoassay that concurrently measures ACTH and CLIP against the reference iACTH assay.

Animals: Twenty-eight university-owned horses (13 PPID, 15 non-PPID).

Methods: Prospective observational study. Resting plasma hormone concentrations in all animals were measured by both methods in all seasons over 1 year, and after thyrotropin releasing hormone (TRH)-stimulation testing once. Bias of the POC-ACTH/CLIP assay was assessed using Spearman correlation analysis and Bland-Altman plots, and precision and linearity of the POC-ACTH/CLIP assay were determined.

Results: For resting and TRH-stimulated ACTH concentrations, the POC-ACTH/CLIP assay and the reference method had good agreement overall (r ≥ 0.94; P < .001) and in PPID animals (r = 0.93, P < .001). Bias was greater in autumn (33.6-35.6 ± 89.5-96 pg/mL) compared to winter/spring (1.6-11.1 ± 8.4-29.6 pg/mL) and in samples with ACTH concentrations ≥ 90 pg/mL (87.8 ± 116.4 pg/mL). Intra- and inter-assay coefficients of variation for the POC-ACTH/CLIP assay were 8.47% and 14.1%, respectively, and assay linearity was excellent (R2 = 0.991). Conclusions and clinical importance: These data demonstrate acceptable field performance for the POC-ACTH/CLIP assay and good agreement with the chemiluminescent iACTH immunoassay, with a larger bias in samples with higher hormone concentrations. Keywords: PPID; endocrinology; hormone; horse; pituitary pars intermedia dysfunction. © The Author(s) 2026. Published by Oxford University Press on behalf of the American College of Veterinary Internal Medicine.