Reproductive steroids testosterone (T) and estrone sulfate (E1S) are used as diagnostic markers for cryptorchidism in horses. The human chorionic gonadotropin (hCG) stimulation test is used as a diagnostic aid because administration of this hormone results in greater incremental differences in circulating steroid concentrations. Thoughts regarding optimal sampling times following hCG administration, however, are inconsistent. Additionally, determination of half-life of these steroids is important in postsurgical samples to confirm complete removal of testicular tissue. Objectives of this study, therefore, were to determine optimal sampling periods for peak T and E1S after hCG administration and half-life of these steroids after castration. Eight pony stallions were randomly assigned to control or treatment groups (5000 IU hCG). Blood samples were collected following hCG administration. Subsequently, stallions were castrated and blood samples were collected post-castration. The T concentrations were greatest at 72 h after hCG and were greater (P < 0.02) in samples from hCG-treated than control animals: 9,903.4 ± 384 and 784.0 ± 192 pg/mL, respectively (Mean ± SEM). The T concentrations were also greater at 1, 12, 24, 48 and 96 h. The E1S concentrations did not change after administration of hCG. The T response to hCG administration was biphasic with a maximal response between 48–96 h after administration. Half-lives of T and E1S were 1.1 and 0.7 h, respectively, and concentration of T and E1S was similar to that of geldings at 24 h post-castration, which, therefore, should be considered an optimal time to ensure complete castration has occurred.

生殖类固醇睾酮 (T) 和硫酸雌酮 (E1S) 被用作马隐睾症的诊断标志物。人绒毛膜促性腺激素 (hCG) 刺激试验被用作诊断辅助手段，因为使用这种激素会导致循环类固醇浓度的增量差异更大。然而，关于 hCG 给药后最佳采样时间的想法是不一致的。此外，确定这些类固醇的半衰期在术后样本中很重要，以确认睾丸组织的完全去除。因此，本研究的目的是确定 hCG 给药后峰值 T 和 E1S 的最佳采样期以及这些类固醇在去势后的半衰期。八匹小马种马被随机分配到对照组或治疗组（5000 IU hCG）。在施用 hCG 后收集血样。随后，种马被阉割并在阉割后收集血样。在 hCG 后 72 小时 T 浓度最大，并且更大（p < 0.02) 在 hCG 治疗的样本中，与对照动物相比：分别为 9,903.4 ± 384 和 784.0 ± 192 pg/mL（平均值 ± SEM）。T 浓度在 1、12、24、48 和 96 小时时也更高。施用 hCG 后 E1S 浓度没有变化。对 hCG 给药的 T 反应是双相的，在给药后 48-96 小时之间达到最大反应。T 和 E1S 的半衰期分别为 1.1 和 0.7 小时，T 和 E1S 的浓度与阉割后 24 小时的阉割相似，因此，应认为这是确保完全阉割的最佳时间.