March 1991

Clinical Significance of Low Serum Thyrotropin Concentration by Chemiluminometric Assay in 85-Year-Old Women and Men

Author Affiliations

From the Department of Geriatrics and Long-term Care Medicine, Vasa Hospital (Drs Sundbeck and Edén), and the Department of Clinical Chemistry, Sahlgren's Hospital (Drs Jagenburg and Lindstedt and Ms Johansson), Gothenburg (Sweden) University.

Arch Intern Med. 1991;151(3):549-556. doi:10.1001/archinte.1991.00400030093017

The prevalence and causes of low serum thyrotropin concentration were studied in 886 individuals at age 85 years (601 women and 285 men). All participants were subject to detailed clinical and biochemical evaluation, including determination of serum thyrotropin and free thyroxine concentrations by chemiluminometric assays. Samples with thyrotropin concentrations below 0.20 mU/L or above 6.0 mU/L and/or free thryoxine concentrations above 22.0 pmol/L were selected for further assays. These selected individuals were followed-up during 3 years. Of 18 individuals without thyroid hormone treatment who had thyrotropin concentrations less than 0.20 pmol/L (13 below 0.10 pmol/L), only two were proved to be hyperthyroid; in another three, hyperthyroidism could not be excluded. The results indicate that most elderly individuals with low serum thyrotropin concentrations are not hyperthyroid and that abnormal thyroxine-binding globulin (in conjunction with drug treatment or nonthyroidal illness) is not a common cause of low thyrotropin concentration.

(Arch Intern Med. 1991;151:549-556)