School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia.
Boehringer Ingelheim Pty Ltd, North Ryde, New South Wales, Australia.
J Vet Intern Med. 2021 Jan;35(1):560-570. doi: 10.1111/jvim.16017. Epub 2020 Dec 24.
Diagnosis of pituitary pars intermedia dysfunction (PPID) is problematic because of large variations in ACTH concentrations.
HYPOTHESIS/OBJECTIVES: Compare the test characteristics of baseline and post-thyrotropin-releasing hormone (TRH) stimulation plasma ACTH concentrations in horses using diagnostic cutoff values (DCOVs) and reference intervals (RIs) and determine the clinical consequences of using each method.
One hundred six mature horses: 72 control cases and 34 PPID cases.
Prospective case-controlled study. Horses underwent monthly TRH stimulation tests. Diagnostic cutoff values were determined monthly by receiver operating characteristic curves using the Youden index. Reference intervals were determined monthly by a robust method. For each case age, sex and body condition score (BCS) were recorded.
Baseline ACTH concentrations varied by month (P < .001) with significant "month × age" (P = .003), "month × sex" (P = .003), and "month × BCS" (P = .007) effects. Baseline ACTH concentrations were accurate to diagnose PPID (0.91 ± 0.06) with DCOVs increasing the test sensitivity (0.61 ± 0.21 to 0.87 ± 0.05, P = .002) and RI increasing test specificity (0.85 ± 0.12 to 0.98 ± 0.01, P = .01). Thyrotropin-releasing hormone stimulation improved test accuracy (0.91 ± 0.06 to 0.97 ± 0.03, P = .004).
ACTH concentrations follow a circannual rhythm and vary with physiological factors. As using DCOVs increases the ability to detect mild cases and using RI decreases the risk of unnecessary treatments, ACTH concentrations should be interpreted within a specific clinical context. The TRH stimulation test improves the diagnosis of PPID.
由于 ACTH 浓度存在较大差异，因此诊断脑垂体中叶功能减退症（PPID）存在问题。
假设/目的：使用诊断截止值（DCOV）和参考区间（RI）比较使用甲状腺素释放激素（TRH）刺激前后基础血浆 ACTH 浓度的马匹的测试特征，并确定使用每种方法的临床后果。
106 匹成熟马：72 匹对照病例和 34 匹 PPID 病例。
前瞻性病例对照研究。马每月进行 TRH 刺激试验。每月通过接收者操作特性曲线使用约登指数确定诊断截止值。每月通过稳健方法确定参考区间。对于每个病例，记录年龄、性别和体况评分（BCS）。
基础 ACTH 浓度随月份而变化（P < .001），具有显著的“月份×年龄”（P =.003）、“月份×性别”（P =.003）和“月份×BCS”（P =.007）效应。基础 ACTH 浓度可准确诊断 PPID（0.91 ± 0.06），DCOV 增加了检测敏感性（0.61 ± 0.21 至 0.87 ± 0.05，P =.002），RI 增加了检测特异性（0.85 ± 0.12 至 0.98 ± 0.01，P =.01）。TRH 刺激提高了检测准确性（0.91 ± 0.06 至 0.97 ± 0.03，P =.004）。
ACTH 浓度遵循年节律变化，并受生理因素影响。由于使用 DCOV 增加了检测轻度病例的能力，而使用 RI 降低了不必要治疗的风险，因此应在特定的临床环境中解释 ACTH 浓度。TRH 刺激试验可改善 PPID 的诊断。
