title: Elevated TSH in adults treated for hypothyroidism is associated with increased mortality.
abstract: BACKGROUND
  Numerous studies investigated the link between hypothyroidism and mortality, but a definite conclusion is hard to reach as these were limited by a number of factors, including age of participants, comorbidities and single measurement of thyroid function.
  
  
  OBJECTIVE
  To evaluate the association between TSH and fT4 levels and mortality in patients with levothyroxine-treated hypothyroidism.
  
  
  METHODS
  Observational data of hospitalized patients (2011-2014). TSH and fT4 levels obtained between at least 30 days after discharge and until death or end of follow-up were collected. Median TSH and fT4 levels were stratified into categories.
  
  
  METHODS
  In total, 611 patients with treated hypothyroidism, aged 60-80 years (72% females, mean age 71 ± 6 years) were included in the study.
  
  
  METHODS
  All-cause mortality up to 66 months after discharge, by TSH and fT4 categories.
  
  
  RESULTS
  During follow-up, the average numbers of TSH and fT4 measurements were 5.5 ± 3.8 and 2.5 ± 4.2 per patient respectively. Mortality rates were 28%, 29% and 54% with median TSH of 0.5-2.5, 2.5-5.0 and 5.0-10.0 IU/L respectively. Adjusted hazard ratios for mortality with median TSH between 5.0 and 10.0 IU/L were 2.3 (95% CI: 1.6-3.4) and 2.2 (95% CI: 1.6-3.2) compared with patients with TSH between 0.5-2.5 IU/L and 2.5-5 IU/L respectively. There was no difference in mortality between patients with median fT4 10-15 or 15-20 pmol/L.
  
  
  CONCLUSIONS
  In treated hypothyroid adult patients and serial measurements of thyroid function tests, median TSH levels of 5-10 IU/L are associated with increased mortality with no effect of fT4 levels. Treatment should aim at achieving euthyroidism to improve survival.
authors.affiliation: Institute of EndocrinologyRabin Medical Center-Beilinson Hospital, Petah Tikva, Israel amit.akirov@gmail.com.|Sackler School of MedicineTel Aviv University, Tel Aviv, Israel.
authors.forename: Amit
authors.initials: A
authors.lastname: Akirov
authors.affiliation: Sackler School of MedicineTel Aviv University, Tel Aviv, Israel.
authors.forename: Hannah
authors.initials: H
authors.lastname: Gimbel
authors.affiliation: Sackler School of MedicineTel Aviv University, Tel Aviv, Israel.|Internal Medicine E.
authors.forename: Alon
authors.initials: A
authors.lastname: Grossman
authors.affiliation: Statistical Consulting UnitRabin Medical Center-Beilinson Hospital, Petah Tikva, Israel.
authors.forename: Tzipora
authors.initials: T
authors.lastname: Shochat
authors.affiliation: Institute of EndocrinologyRabin Medical Center-Beilinson Hospital, Petah Tikva, Israel.|Sackler School of MedicineTel Aviv University, Tel Aviv, Israel.
authors.forename: Ilan
authors.initials: I
authors.lastname: Shimon
mesh_terms: D000368:Aged; D005260:Female; D006728:Hormones / Q000494:pharmacology / Q000627:therapeutic use; D006801:Humans; D007037:Hypothyroidism / Q000097:blood* / Q000188:drug therapy / Q000401:mortality*; D008297:Male; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000494:pharmacology / Q000627:therapeutic use; D014284:Triiodothyronine / Q000097:blood
chemical_list: D006728:Hormones; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine