title: Factors affecting the serum free thyroxine levels in hospitalized chronic geriatric patients.
abstract: OBJECTIVE
  Determination of whether nonthyroidal factors affect the diagnostic value of free thyroxine estimation in geriatric patients.
  
  
  METHODS
  Survey.
  
  
  METHODS
  A convenience sample of 381 non-selected, chronic, hospitalized geriatric patients over 60 years of age (I = relatively good health; II = relatively poor health; III = bad health; subgroups "sine therapia," ie, patients receiving no drugs that affect FT4) and 180 20-40 year old healthy persons.
  
  
  METHODS
  Thyrotropin-releasing hormone test; thyrotropin (TSH); free thyroxine (FT4, measured in part by two parallel methods) estimation in a screening study; and thyroxine-binding globulin and thyroxine-binding-inhibitor activity measurements.
  
  
  RESULTS
  The normal FT4 ranges of the euthyroid geriatric (n = 210) and healthy young groups were similar. In the "sine therapia" euthyroid patients, FT4 decreased with age but increase with the severity of illness. High FT4 levels with non-suppressed TSH were more frequent in patients in poor and bad health. (I = 6/112; II = 14/140; III = 13/74; P < 0.01). The serum thyroxine-binding-inhibitor activity of euthyroid geriatric patients correlated with the severity of their clinical state (I = 6.22 +/- 5.65 (13); II = 7.40 +/- 4.33 (23); III = 10.04 +/- 5.50 (16) micrograms merthiolate equivalent/microL; ANOVA with log-transformed values: F(2.51) = 3.50, P < 0.05). The mean FT4 was higher in 36 heparin-treated patients (22.81 +/- 4.67 pmol/L) than in the 193 "sine therapia" patients (19.03 +/- 4.23 pmol/L; -P < 0.001). In a convenience subsample of 240 patients, a weak inverse correlation was found between FT4 and the thyroxine-binding globulin (r = -0.14, P < 0.02). Only 5/11 patients with low free thyroxine had hypothyroidism, while 11/46 patients with elevated free thyroxine had hyperthyroidism.
  
  
  CONCLUSIONS
  There is no need to modify the normal free thyroxine range for hospitalized geriatric patients. Clinical condition, drug treatment, and, to a lesser extent, age are factors that significantly affect the diagnostic value of FT4 in hospitalized chronic geriatric patients, decreasing the specificity of the test in diagnosing clinical hyper- and hypothyroidism.
authors.affiliation: 1st Department of Medicine, Postgraduate Medical University, Budapest, Hungary.
authors.forename: I
authors.initials: I
authors.lastname: Szabolcs
authors.forename: C
authors.initials: C
authors.lastname: Ploenes
authors.forename: M
authors.initials: M
authors.lastname: Beyer
authors.forename: W
authors.initials: W
authors.lastname: Bernard
authors.forename: J
authors.initials: J
authors.lastname: Herrmann
mesh_terms: D000203:Activities of Daily Living; D000328:Adult; D000367:Age Factors; D000368:Aged; D002908:Chronic Disease; D005260:Female; D006304:Health Status; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay; D012737:Sex Factors; D013959:Thyroid Diseases / Q000175:diagnosis; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood*; D013975:Thyroxine-Binding Proteins / Q000032:analysis / Q000037:antagonists & inhibitors
chemical_list: D013975:Thyroxine-Binding Proteins; D013972:Thyrotropin; D013974:Thyroxine