Age modulates effects of thyroid dysfunction on sex hormone binding globulin (SHBG) levels.

Symptoms of thyroid dysfunction are difficult to detect in elderly people and TSH is sometimes unreliable. We therefore tested the value of SHBG as a marker of thyroid hormone action on the liver to determine the thyroid status of elderly people. Aging euthyroid men and women have a significant increase in SHBG (p > 0.0001). In aging women the decrease in SHBG with hypothyroidism and increase with hyperthyroidism are highly significant (p < 0.0001 and p < 0.0005 respectively). No significant variation in SHBG was observed in men with thyroid dysfunction. SHBG can help to determine the thyroid status of aging women.