TY - JOUR
T1 - Free thyroxine and functional mobility, fitness, and fatigue in euthyroid older men and women in the Baltimore Longitudinal Study of Aging
AU - Simonsick, Eleanor M.
AU - Chia, Chee W.
AU - Mammen, Jennifer S.
AU - Egan, Josephine M.
AU - Ferrucci, Luigi
N1 - Funding Information:
This research was supported by the Intramural Research Program of the National Institute on Aging, National Institutes of Health.
PY - 2016/7
Y1 - 2016/7
N2 - Background: Emerging evidence suggests that mildly down-regulated thyroid function in older persons may protect and/or reflect maintained health. Methods: Using observational data collected between January 2006 and March 2014 on a volunteer sample of 602 men and women aged 68-97 years with normal thyroid function participating in the Baltimore Longitudinal Study of Aging, this study examines the concurrent relationship between reported walking ability, usual and rapid gait speed, endurance walk performance, fatigability, and reported energy level with respect to free thyroxine (FT4) within the normal range (0.76-1.50 ng/dL) as a continuous variable and categorized as low (lower quartile), medium (interquartile), or high (upper quartile). Results: Adjusting for sex, age, race, height, weight, exercise and smoking, reported walking ability, usual and rapid gait speed, 400-m time, fatigability, and reported energy level were less favorable with increasing FT4 (p=.013 to <.001). In sex-strata, similar associations were observed except for walking ability in men and energy level in women. Categorical analyses revealed that persons with low FT4 exhibited better functional mobility, fitness, and reported energy than persons with intermediate or high levels (p <.05 for all). Persons with high-normal versus medium FT4 had slower usual and rapid gait speed (p <.05) only. Conclusion: Older adults with low-normal FT4 exhibit better mobility, fitness, and fatigue profiles. Mildly down-regulated thyroid function appears to align with better function in old age and may serve as a biomarker of healthy longevity.
AB - Background: Emerging evidence suggests that mildly down-regulated thyroid function in older persons may protect and/or reflect maintained health. Methods: Using observational data collected between January 2006 and March 2014 on a volunteer sample of 602 men and women aged 68-97 years with normal thyroid function participating in the Baltimore Longitudinal Study of Aging, this study examines the concurrent relationship between reported walking ability, usual and rapid gait speed, endurance walk performance, fatigability, and reported energy level with respect to free thyroxine (FT4) within the normal range (0.76-1.50 ng/dL) as a continuous variable and categorized as low (lower quartile), medium (interquartile), or high (upper quartile). Results: Adjusting for sex, age, race, height, weight, exercise and smoking, reported walking ability, usual and rapid gait speed, 400-m time, fatigability, and reported energy level were less favorable with increasing FT4 (p=.013 to <.001). In sex-strata, similar associations were observed except for walking ability in men and energy level in women. Categorical analyses revealed that persons with low FT4 exhibited better functional mobility, fitness, and reported energy than persons with intermediate or high levels (p <.05 for all). Persons with high-normal versus medium FT4 had slower usual and rapid gait speed (p <.05) only. Conclusion: Older adults with low-normal FT4 exhibit better mobility, fitness, and fatigue profiles. Mildly down-regulated thyroid function appears to align with better function in old age and may serve as a biomarker of healthy longevity.
KW - Aging
KW - Fatigue
KW - Fitness
KW - Free thyroxine
KW - Physical function
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U2 - 10.1093/gerona/glv226
DO - 10.1093/gerona/glv226
M3 - Article
C2 - 26791089
AN - SCOPUS:84979236355
SN - 1079-5006
VL - 71
SP - 961
EP - 967
JO - Journals of Gerontology - Series A Biological Sciences and Medical Sciences
JF - Journals of Gerontology - Series A Biological Sciences and Medical Sciences
IS - 7
ER -