OBJECTIVES: Thyroid autoimmunity decreases in the very old. We investigated whether glucocorticoid (GC) activity, which increases in old age, is involved in this process. SUBJECTS AND METHODS: A total of 321 ambulatory subjects (age 51-95 years, median 71, 207 female) were studied. Thyroid function tests, cortisol, glucose, insulin and biochemical parameters were measured. A modified overnight dexamethasone suppression test (0.25 mg) was performed as an index of GC sensitivity. RESULTS: Forty subjects had positive anti-thyroid peroxidase antibodies and 36 had positive anti-thyroglobulin antibodies, while 57 had either one or the other or both thyroid autoantibodies (ThAbs) positive. Mean basal cortisol levels were significantly lower in the ThAbs (+) groups (320+/-125 vs 378+/-128 nmol/l, P=0.002). Triiodothyronine, free thyroxine, post-dexamethasone cortisol levels, C-reactive protein, homeostasis model assessment-insulin-resistance-index and body mass index did not differ between these two groups. Mean age of ThAbs (+) subjects was lower compared to the ThAbs (-) group (67.38+/-7.38 vs 71.64+/-8.57 years, P=0.001). CONCLUSIONS: Reduced GC activity is associated with an increased prevalence of ThAbs positivity in older ambulatory subjects. Subjects without ThAbs in this population sample are relatively older. It is not known whether this is related to increasing GC activity with age.
OBJECTIVES: Thyroid autoimmunity decreases in the very old. We investigated whether glucocorticoid (GC) activity, which increases in old age, is involved in this process. SUBJECTS AND METHODS: A total of 321 ambulatory subjects (age 51-95 years, median 71, 207 female) were studied. Thyroid function tests, cortisol, glucose, insulin and biochemical parameters were measured. A modified overnight dexamethasone suppression test (0.25 mg) was performed as an index of GC sensitivity. RESULTS: Forty subjects had positive anti-thyroid peroxidase antibodies and 36 had positive anti-thyroglobulin antibodies, while 57 had either one or the other or both thyroid autoantibodies (ThAbs) positive. Mean basal cortisol levels were significantly lower in the ThAbs (+) groups (320+/-125 vs 378+/-128 nmol/l, P=0.002). Triiodothyronine, free thyroxine, post-dexamethasonecortisol levels, C-reactive protein, homeostasis model assessment-insulin-resistance-index and body mass index did not differ between these two groups. Mean age of ThAbs (+) subjects was lower compared to the ThAbs (-) group (67.38+/-7.38 vs 71.64+/-8.57 years, P=0.001). CONCLUSIONS: Reduced GC activity is associated with an increased prevalence of ThAbs positivity in older ambulatory subjects. Subjects without ThAbs in this population sample are relatively older. It is not known whether this is related to increasing GC activity with age.
Authors: Luigi Petramala; Federica Olmati; Maria Gabriella Conforti; Antonio Concistré; Valeria Bisogni; Nikita Alfieri; Gino Iannucci; Giorgio de Toma; Claudio Letizia Journal: Int J Endocrinol Date: 2018-12-18 Impact factor: 3.257