Elevated TSH Levels in the Elderly: A Clinical Problem

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 437-470-Non-neoplastic Thyroid Disorders
Basic/Clinical
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-446
Timothy M Buckey1, Charlotte M Melvin2, John Eng3, Joshua Estrada4 and Offie P Soldin*4
1Georgetown University, Washington, DC, 2Georgetown University Medical Center, 3Georgetown University Hospital, Washington, DC, 4Georgetown University Medical Center, Washington, DC
Background: Current immunoassay methods often yield high serum thyroid stimulating hormone (TSH) levels for the elderly even if they show no clinical symptoms of hypothyroidism. Previous research has shown that overtreatment of mild (subclinical) hypothyroidism with levothyroxine (LT4) may cause serious health problems, including adverse cardiovascular effects. Over the past two decades, the upper TSH reference limit has declined from 10 mIU/L to 2.5-3.5 mIU/L. This decrease is due to several factors, namely the improved sensitivity and specificity of monoclonal antibody-based immunometric TSH assays, the exclusion of those individuals with subclinical autoimmune thyroid disease from the reference population, and the elimination of high values that are due to cross-reactivity problems with other glycoproteins.  The controversy surrounding the lowering of the TSH upper reference limit is that it may lead to the unnecessary treatment of healthy individuals. Indeed, TSH serum levels between 3.0 and 4.5 may be an early indicator of hypothyroidism; however, an upper reference interval of 2.5-3.0 mIU/L would yield a 300-400% increase in the number of patients who are clinically not in need of LT4 treatment.

Objective: To examine if increased levels of TSH with increased age are partly due to the increased presence of biologically inactive isoforms of TSH.

Methods: We obtained 148 serum samples with elevated TSH from patients from 6/2012-1/2013 at the Georgetown University Hospital. Inclusion criteria were only serum samples that had TSH concentrations greater than 5 uIU/mL. Patient ages ranged between 4-96y.

Results and conclusions: 72% of the 148 samples were female serum samples, ages raged from 22-96y, >70 62%. 43% of the subjects were older than 70 years. TBII was positive for 33%, (60% of these were females), TSI was positive for 14% (all female), TPOAb were present in 41% and TgAb in 16.3%. When stratified by age, namely <50yrs, 50-59, 60-69, and >70 years old, data analysis showed a trend of increase in serum TSH concentrations with increasing age.

Nothing to Disclose: TMB, CMM, JE, JE, OPS

*Please take note of The Endocrine Society's News Embargo Policy at http://www.endo-society.org/endo2013/media.cfm

Sources of Research Support: NIH R01 AG033867