title: Two-step thyroid screening strategy in the critical patient.
abstract: BACKGROUND
  Thyroid function biochemical tests are known for their usefulness in prognosis of long-term critical patients, although current data are controversial regarding the clinical benefit of both free triiodothyronine and thyroxine as prognostic thyroid markers during the first 48h after Intensive Care Unit (ICU) admission.
  
  
  METHODS
  The aim of this study was to evaluate the usefulness of two strategies for thyroid function assessment in the first 48h after admission at the ICU. The usefulness of a two-step biochemical thyroid strategy (initial isolated TSH determination, followed by subsequent fT4 and fT3) was compared with a complete one-step biochemical profile (TSH+fT4+fT3).
  
  
  RESULTS
  No significant differences were found between the rates of thyroid dysfunction detection when using both strategies (2.8% vs. 2.4%; p=0.71). Using the two-step strategy and a 2.5μUI/mL cut-off value for TSH, sensitivity and negative predictive value were 100%. Among patients with an altered fT3 only, mortality was 14% if TSH≤2.5μUI/mL, whereas it was 7% if TSH>2.5μUI/mL (p=0.008).
  
  
  CONCLUSIONS
  For patients with critical illness, the early two-step thyroid screening strategy (starting with an isolated TSH determination between 24 and 48h after admission) led to a saving of 50% in fT4 and fT3 tests, with a false-negative rate of 1.3%. This represents an improved diagnostic approach, hence avoiding the performance of unnecessary complementary biochemical measurements.
authors.affiliation: Department of Laboratory Medicine, Hospital Universitari Son Espases, Palma, Balearic Islands, Spain; Institut d'Investigació Sanitària de Palma (IdISPa), Palma, Balearic Islands, Spain. Electronic address: dr.morell.uab@gmail.com.
authors.forename: Daniel
authors.initials: D
authors.lastname: Morell-Garcia
authors.affiliation: Department of Laboratory Medicine, Hospital Universitari Son Espases, Palma, Balearic Islands, Spain; Institut d'Investigació Sanitària de Palma (IdISPa), Palma, Balearic Islands, Spain.
authors.forename: Josep Miquel
authors.initials: JM
authors.lastname: Bauça
authors.affiliation: Department of Laboratory Medicine, Hospital Universitari Son Espases, Palma, Balearic Islands, Spain.
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Elorza
authors.affiliation: Department of Laboratory Medicine, Hospital Universitari Son Espases, Palma, Balearic Islands, Spain; Institut d'Investigació Sanitària de Palma (IdISPa), Palma, Balearic Islands, Spain.
authors.forename: Antonia
authors.initials: A
authors.lastname: Barcelo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood*; D016638:Critical Illness; D005260:Female; D005500:Follow-Up Studies; D006760:Hospitalization; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008403:Mass Screening / Q000379:methods*; D008875:Middle Aged; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate; D013959:Thyroid Diseases / Q000097:blood / Q000175:diagnosis* / Q000401:mortality*; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000378:metabolism / Q000473:pathology; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine
keywords: Critical illness; Screening; Thyroid profile; Thyrotropin