Piticchio T, Luongo C, Trimboli P, Salvatore D, Frasca F
Endocrinology Section, Department of Clinical and Experimental Medicine, Garibaldi Nesima Hospital, University of Catania, Catania, Italy.
Department of Medicine and Surgery, University of Enna "Kore", Enna, Italy.
J Endocrinol Invest. 2025 Mar;48(3):587-596. doi: 10.1007/s40618-024-02480-6. Epub 2024 Oct 21.
Hypothalamic-pituitary thyrotropic activity (HPta) is crucial since TSH is the mainstay for evaluating primary hypothyroidism (hT) and replacement therapy in clinical practice. Despite TSH values, some patients experience symptoms and metabolic alterations, raising several issues about hT. The aim of the study was to investigate factors influencing the TSH values achieved after a period of hT induced in a standardized and controlled manner (TSH_time1).
Our institutional database was searched to extract records of differentiated thyroid cancer (DTC) patients undergoing a LT4 withdrawal protocol prior to radioiodine (RAI) administration. We collected clinical and biochemical parameters before LT4 discontinuation and after one month of induced hT. We performed Mann-Whitney U-test and linear regression analyses.
We included 102 patients, with a median age of 44 years. In univariate analyses, TSH_time1 was correlated with age (p 0.005) and the dose pro Kg/die of LT4 assumed until the discontinuation of LT4 (LT4_dose) (p 0.023). The higher the age, the lower the TSH_time1 level. The higher the LT4_dose, the higher the TSH_time1 level. After multivariate analysis, the fittest model included age, BMI, LT4_dose, and systemic inflammation response index with an adjusted R of 0.4.
The study highlights new mechanisms that influence HPta. HPta progressively reduces with age, and this must be considered when evaluating TSH values in the elderly. Furthermore, we report for the first time a rebound effect of HPta, determined by the dose pro Kg/die of LT4 taken prior to its discontinuation. Inflammation and metabolic status also affect these phenomena.
下丘脑 - 垂体促甲状腺素活性（HPta）至关重要，因为促甲状腺激素（TSH）是临床实践中评估原发性甲状腺功能减退症（hT）及替代治疗的主要依据。尽管有TSH值，但一些患者仍出现症状和代谢改变，引发了关于hT的若干问题。本研究的目的是调查在以标准化和可控方式诱导hT一段时间后（TSH_time1）影响所达到的TSH值的因素。
检索我们机构的数据库，以提取在放射性碘（RAI）给药前接受左甲状腺素（LT4）撤药方案的分化型甲状腺癌（DTC）患者的记录。我们收集了LT4停药前及诱导hT一个月后的临床和生化参数。我们进行了曼 - 惠特尼U检验和线性回归分析。
我们纳入了102例患者，中位年龄为44岁。在单变量分析中，TSH_time1与年龄（p = 0.005）以及直至LT4停药时所服用的LT4每千克每日剂量（LT4_dose）（p = 0.023）相关。年龄越高，TSH_time1水平越低。LT4_dose越高，TSH_time1水平越高。多变量分析后，最合适的模型包括年龄、体重指数、LT4_dose和全身炎症反应指数，调整后的R值为0.4。
该研究突出了影响HPta的新机制。HPta随年龄逐渐降低，在评估老年人的TSH值时必须考虑这一点。此外，我们首次报告了HPta的反弹效应，这是由停药前服用的LT4每千克每日剂量所决定的。炎症和代谢状态也影响这些现象。
