Analysis on variation tendency of serum thyroid hormone level in the healthy elderly aged over 80 years / 中华老年医学杂志

ABSTRACT

Objective To explore the variation tendency of serum thyroid hormone level in the elderly aged over 80 years.Methods The 602 healthy volunteers were divided into 3 groups by ageyoung group (20-59 years of age,n= 226),elderly group (60-79 years of age,n= 195),and advanced age group (80-102 years of age,n=181).Fasting blood of all persons was harvested,then the levels of serum total triiodothyroxine (TT3),total thyroxine (TT4),free tri-iodothyronine (FT3),free thyroxine (FT4),thyroid-stimulating hormone (TSH) and reverse tri-iodothyronine (rT3) were determined by chemistry luminescence technique and radioimmunoassay.Statistical analysis was made by the software SPSS 13.0.Results The levels of serum FT3 and TT3 were lower in elderly group than in young group (t=2.793,3.627,P=0.005,0.000).There were significant differences in the levels of serum TT3,TT4,FT3,TSH and rT3 between young group and advanced-age group (t =10.930,6.065,15.398,- 2.933,- 5.643,all P = 0.000),also between elderly group and advanced-age group (t= 8.382,4.298,11.573,-3.383,-5.148,all P＜0.001).The levels of serum FT3,TT3 and TT4 were negatively correlated with age (r=- 0.51,-0.39 and -0.25,respectively,all P＜0.01).And the levels of serum rT3 and TSH showed positive relationships with age (r=0.32,0.12,all P＜0.01).There were no relationships between the level of serum FT4 and age.The positive rate of serum TT3,TT4,FT3,FT4,TSH and rT3 concentration beyond the reference value was 0,0,13.8%,0,6.6% and 21% in advanced-age group,respectively.Conclusions The levels of serum thyroid hormone and thyroid-stimulating hormone change with age.The levels of FT3,rT3 and TSH change obviously in the elderly aged over 80 years.It could reduce the false positive rate in clinical practice if normal reference range for serum thyroid hormone levels in different aged elderly is established.