Free thyroxine but not TSH levels are associated with decline in functional status in a cohort of geriatric outpatients.

Purpose: To assess the associations between TSH and free thyroxine (FT4) levels and decline in functional status in euthyroid older patients at risk of frailty.

Design: Longitudinal prospective study.

Methods: Participants from the geriatric outpatient clinic of a university hospital, who fulfilled the criteria for frailty or were at risk of frailty, were recruited.