Magri F, Muzzoni B, Cravello L, Fioravanti M, Busconi L, Camozzi D, Vignati G, Ferrari E
Department of Internal Medicine and Medical Therapy, University of Pavia, Italy.
Metabolism. 2002 Jan;51(1):105-9. doi: 10.1053/meta.2002.28968.
Changes in thyroid function are often described in elderly subjects; however, their pathophysiologic significance and the possible contributory role of both malnutrition and nonthyroidal illness are still debated. The aim of this cross-sectional study was to investigate thyroid function in relationship to some markers of the nutritional status in a group of healthy old subjects and in some centenarians living in nursing homes. Patients included 24 clinically healthy elderly women (age, 71 to 93 years), 24 clinically healthy centenarian women (age, 100 to 106 years), and 20 healthy young subjects (age, 22 to 33 years). Blood samples were drawn from each subject for the evaluation of thyroid-stimulating hormone (TSH), free triiodothyronine (FT(3)), free thyroxine (FT(4),) reverseT(3) (rT3), autoantibodies against thyroglobulin (AbTg) and against thyroid peroxidase (AbTPO), and for the main humoral nutritional markers. TSH and thyroid hormones were assayed by fluoroimmunometric method; rT3 and thyroid autoantibodies by radioimmunoassay (RIA) and enzyme chemiluminescent immunometric assay, respectively. The mean values of TSH, FT(3) and FT(4) fell within the normal range in both groups. However, by comparison to old controls, in centenarian subjects, TSH levels were significantly lower, whereas rT(3) concentrations were slightly, but significantly, increased. Autoantibodies positivity was found in 4.16% of centenarians and in 10.4% and 13.6% of old and young controls. Thus, the incidence of thyroid autoantibodies was lower in centenarians than in old controls. Except for transferrin, lower than the normal range in centenarians, all of the other nutritional markers evaluated fell within the laboratory range of normality. Total cholesterol levels were significantly reduced in centenarians by comparison to old controls. Our results showed an age-related decline of the TSH levels and a significant increase of the rT(3) concentrations in centenarians by comparison to old controls. These findings may be related to an age-dependent reduction of the 5'-deiodinase activity rather than to important changes of nutritional markers.
甲状腺功能变化在老年受试者中常有描述；然而，其病理生理意义以及营养不良和非甲状腺疾病可能的促成作用仍存在争议。这项横断面研究的目的是调查一组健康老年受试者以及一些住在养老院的百岁老人的甲状腺功能与营养状况的某些标志物之间的关系。患者包括24名临床健康的老年女性（年龄71至93岁）、24名临床健康的百岁女性（年龄100至106岁）以及20名健康年轻受试者（年龄22至33岁）。从每位受试者采集血样，以评估促甲状腺激素（TSH）、游离三碘甲状腺原氨酸（FT(3)）、游离甲状腺素（FT(4)）、反三碘甲状腺原氨酸（rT3）、抗甲状腺球蛋白自身抗体（AbTg）和抗甲状腺过氧化物酶自身抗体（AbTPO），以及主要的体液营养标志物。TSH和甲状腺激素通过荧光免疫分析法测定；rT3和甲状腺自身抗体分别通过放射免疫分析法（RIA）和酶化学发光免疫分析法测定。两组的TSH、FT(3)和FT(4)平均值均在正常范围内。然而，与老年对照组相比，百岁老人的TSH水平显著降低，而rT(3)浓度略有但显著升高。百岁老人中自身抗体阳性率为4.16%，老年和年轻对照组中分别为10.4%和13.6%。因此，百岁老人中甲状腺自身抗体的发生率低于老年对照组。除了百岁老人中低于正常范围的转铁蛋白外，所评估的所有其他营养标志物均在实验室正常范围内。与老年对照组相比，百岁老人的总胆固醇水平显著降低。我们的结果显示，与老年对照组相比，百岁老人的TSH水平随年龄下降，rT(3)浓度显著升高。这些发现可能与5'-脱碘酶活性随年龄降低有关，而非与营养标志物的重要变化有关。
