Thyroid hormone concentrations, disease, physical function, and mortality in elderly men.
BACKGROUND
Physiological changes in thyroid hormone concentrations might be related to changes in the overall physical function in the elderly.


OBJECTIVE
We determined to what extent thyroid hormone concentrations are related to physical function and mortality in elderly men.


METHODS
A longitudinal population study (the Zoetermeer study) was conducted. Mortality was registered in the subsequent 4 yr.


METHODS
Four hundred three independently and ambulatory living men (aged 73-94 yr) participated.


METHODS
The study examined the association between serum thyroid hormones and parameters of physical function as well as the association with mortality.


METHODS
TSH, free T4 (FT4) total T4, T3, rT3, and T4-binding globulin were measured. Physical function was estimated by the number of problems in activities of daily living, a measure of physical performance score (PPS), leg extensor strength and grip strength, bone density, and body composition.


RESULTS
Serum rT3 increased significantly with age and the presence of disease. Sixty-three men met the biochemical criteria for the low T3 syndrome (decreased serum T3 and increased serum rT3). This was associated with a lower PPS, independent of disease. Furthermore, higher serum FT4 (within the normal range of healthy adults) and rT3 (above the normal range of healthy adults) were related with a lower grip strength and PPS, independent of age and disease. Isolated low T3 was associated with a better PPS and a higher lean body mass. Low FT4 was related to a decreased risk of 4-yr mortality.


CONCLUSIONS
In a population of independently living elderly men, higher FT4 and rT3 concentrations are associated with a lower physical function. High serum rT3 may result from a decreased peripheral metabolism of thyroid hormones due to the aging process itself and/or disease and may reflect a catabolic state. Low serum FT4 is associated with a better 4-yr survival; this may reflect an adaptive mechanism to prevent excessive catabolism.
van den Beld
Annewieke W
AW
Department of Internal Medicine, Room Bd230, Erasmus Medical Center, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands. a.vandenbeld@erasmusmc.nl
Visser
Theo J
TJ
Feelders
Richard A
RA
Grobbee
Diederick E
DE
Lamberts
Steven W J
SW
D000203:Activities of Daily Living; D000368:Aged; D000375:Aging / Q000097:blood*; D001823:Body Composition; D015519:Bone Density; D003430:Cross-Sectional Studies; D018737:Hand Strength; D006801:Humans; D006980:Hyperthyroidism / Q000401:mortality* / Q000503:physiopathology*; D007037:Hypothyroidism / Q000401:mortality* / Q000503:physiopathology*; D007866:Leg; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology; D009994:Osmolar Concentration; D010809:Physical Fitness; D013963:Thyroid Hormones / Q000097:blood*
D013963:Thyroid Hormones