title: Baseline levels and trimestral variation of triiodothyronine and thyroxine and their association with mortality in maintenance hemodialysis patients.
abstract: OBJECTIVE
  Conflicting evidence exists with regard to the association of thyroid hormones and mortality in dialysis patients. This study assesses the association between basal and trimestral variation of thyroid stimulating hormone, triiodothyronine, and thyroxine and mortality.
  
  
  METHODS
  In 210 prevalent hemodialysis patients, serum triiodothyronine, thyroxine, thyroid stimulating hormone, and interleukin-6 were measured 3 months apart. Cardiovascular and non-cardiovascular deaths were registered during follow-up. Based on fluctuations along tertiles of distribution, four trimestral patterns were defined for each thyroid hormone: persistently low, decrease, increase, and persistently high. The association of baseline levels and trimestral variation with mortality was investigated with Kaplan-Meier curves and Cox proportional hazard models.
  
  
  RESULTS
  During follow-up, 103 deaths occurred. Thyroid stimulating hormone levels did not associate with mortality. Patients with relatively low basal triiodothyronine concentrations had higher hazards of dying than patients with high levels. Longitudinally, patients with persistently low levels of triiodothyronine during the 3-month period had higher mortality hazards than those having persistently high levels. These associations were mainly attributable to cardiovascular-related mortality. The association between thyroxine and mortality was not altered after adjustment for triiodothyronine.
  
  
  CONCLUSIONS
  Hemodialysis patients with reduced triiodothyronine or thyroxine levels bear an increased mortality risk, especially due to cardiovascular causes. This was true when considering both baseline measurements and trimestral variation patterns. Our longitudinal design adds observational evidence supporting the hypothesis that the link may underlie a causal effect.
authors.affiliation: Department of Clinical Epidemiology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Christiaan L
authors.initials: CL
authors.lastname: Meuwese
authors.forename: Friedo W
authors.initials: FW
authors.lastname: Dekker
authors.forename: Bengt
authors.initials: B
authors.lastname: Lindholm
authors.forename: Abdul R
authors.initials: AR
authors.lastname: Qureshi
authors.forename: Olof
authors.initials: O
authors.lastname: Heimburger
authors.forename: Peter
authors.initials: P
authors.lastname: Barany
authors.forename: Peter
authors.initials: P
authors.lastname: Stenvinkel
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Carrero
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D006435:Renal Dialysis / Q000401:mortality*; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*
chemical_list: D015850:Interleukin-6; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine