BACKGROUND: In dialysis patients, the prevalence of thyroid disorders and their 
impact on specific cardiovascular (CV) events and mortality are largely unknown. 
The aim of the present study was to analyze whether subclinical thyroid 
disorders were associated with CV events and mortality.
STUDY DESIGN: Prospective multicenter cohort study.
SETTING & PARTICIPANTS: Thyroid status and clinical outcomes were explored in 
1,000 diabetic hemodialysis patients from 178 centers in Germany.
PREDICTOR: Thyroid status, defined by the following cutoff values: euthyroidism 
(thyrotropin [TSH], 0.30-4.0 mIU/L; free triiodothyronine [T3], 2.7-7.6 pmol/L; 
and free thyroxine [T4], 11.0-24.0 pmol/L), subclinical hyperthyroidism (TSH<0.3 
mIU/L and free T3/free T4 within reference ranges), subclinical hypothyroidism 
(TSH, 4.1-15.0 mIU/L and free T3/free T4 within reference ranges), euthyroid 
sick syndrome (free T3<2.7 pmol/L and TSH/free T4 low or within reference 
ranges).
OUTCOMES: During 4 years' follow-up, prespecified adjudicated end points were 
determined: sudden cardiac death, myocardial infarction, stroke, combined CV 
events, and overall mortality. Short-term effects within the first 12 months 
were contrasted to long-term effects (years 2-4).
MEASUREMENTS: TSH, free T3, and free T4 levels at baseline.
RESULTS: Euthyroidism was present in 78.1% of patients; subclinical 
hyperthyroidism, in 13.7%; and subclinical hypothyroidism, in 1.6%. Euthyroid 
sick syndrome was exhibited by 5.4% of patients. The adjusted short-term risk of 
sudden cardiac death was more than doubled (HR, 2.03; 95% CI, 0.94-4.36) in 
patients with subclinical hyperthyroidism, and similarly for patients with 
euthyroid sick syndrome (HR, 2.74; 95% CI, 0.94-7.98) compared with patients 
with euthyroidism. Short-term mortality was increased almost 3-fold for patients 
with euthyroid sick syndrome (HR, 2.97; 95% CI, 1.66-5.29), but this effect was 
not seen in the long term. Subclinical hypothyroidism was not associated with CV 
events or all-cause mortality. Risks of stroke and myocardial infarction were 
not affected meaningfully by thyroid disorders.
LIMITATIONS: Observational study design.
CONCLUSIONS: Sudden cardiac death may be influenced by subclinical 
hyperthyroidism and euthyroid sick syndrome in the short term. Furthermore, 
euthyroid sick syndrome is associated strongly with mortality in hemodialysis 
patients. Regular assessment of thyroid status may help estimate the cardiac 
risk of dialysis patients.