FREE THYROID HORMONES, BUT NOT TSH, ARE INDEPENDENT PREDICTORS OF ALL CAUSE MORTALITY AND CARDIOVASCULAR MORTALITY

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SUN 414-431-HPT Axis Biology
Clinical
Sunday, June 16, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SUN-421
Anette Merke*1, Jurgen Merke1 and Winfried Maerz2
1Thyroid Center Bergstrasse, Bensheim, Germany, 2MANNHEIM INSTITUTE OF PUBLIC HEALTH, RUPERTUS CAROLA UNIVERSITY HEIDELBERG, MEDICAL FACULTY MANNHEIM, GERMANY, Mannheim, Germany
Objective: The LURIC study (LUdwigshafen RIsk and Cardiovascular Health Study) is a large prospective cohort study. 3316 patients with German ancestry were included between June 1997 and May 2001. Main inclusion criterium was clinical stability except for acute coronary syndrome. All patients were referred to angiography. Subjects were followed up in 2010 for mortality from all causes and from cardiovascular events. Thyroid function is well known to be of vital importance on health, above all in the cardiovascular system.  Thyroid disorders are discussed to have an impact on long-term prognosis and mortality. Therefore we examined whether alterations in thyroid function are associated with mortality from cardiovascular and all causes in patients of the LURIC study.

Methods:
We examined 2507 subjects out of 3316 with angiographic proven CAD and matched controls in which CAD had been ruled out by angiography. Subjects with overt thyroid disease and those receiving thyroid medication and those with medication with direct influence on thyroid metabolism were excluded. Only data of those subjects who had a full set of thyroid hormones were included.Eligible Subjects were classified into quartiles for TSH, fT4 and fT3 levels. We used the COX proportional hazards model to examine the association between thyroid hormone levels and mortality from all causes and cardiovascular causes. Multivariable adjustments were also carried out.

Results:
Our findings show that patients with ft4 levels over 18 pmol/L, defined as the highest fT4 quartile, have the highest mortality from all causes: HR 1.52 and also from cardiovascular causes: HR 1.77. Ref Value HR 1.00, lowest quartile.

Patients with fT3 Levels in the lowest quartile (1.1-4.2 pmol/L), HR 1.00, reference Value, have the highest mortality risk from all causes as well as from cardiovascular causes with constantly  decreasing  HRs up to the forth quartile with fT3 ≥5.4 pmol/L. HR from all causes 0.54 (CI 95% 0.44-0.67). HR from cardiovascular causes 0.47( CI 95% 0.36-0.61).These findings were robust against adjustment for age and sex. TSH showed no correlation with all cause mortality or cardiovascular events.

Discussion:
High fT4 and low fT3 levels in thyroid healthy Caucasians undergoing angiography independently predict  mortality from cardiovascular causes and from all causes. The results underline the importance of fT4 and fT3 levels in the risk evaluation of long time total and cardiovascular mortality of ACS patients without thyroid disorders or thyroid treatment. To our surprise TSH did not show any association with long term mortality, not even in the unadjusted statistic models. The reason for this is still unknown. Recent studies have demonstrated that low TSH is not associated with long term mortality.

Conclusion:: Free thyroid hormones, but not TSH, predict long term mortality risk in Caucasians without thyroid disease.

Nothing to Disclose: AM, JM, WM

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