Reference intervals of serum thyroid function tests in a previously iodine-deficient area.
OBJECTIVE
We undertook the present study to establish reference data for serum thyroid function tests in a previously iodine-deficient area.


METHODS
Data from 4298 individuals, 20-79 years of age were available for the present analysis. Thyroid function (thyrotropin [TSH], free triiodothyronine [FT(3)], and free thyroxine [FT(4)]) and serum autoantibodies to thyroperoxidase (anti-TPOAb) were evaluated from blood samples. Thyroid structure and size were measured by ultrasound.


RESULTS
A reference population was selected comprising 1488 persons (825 men) by excluding subjects with known thyroid diseases, and with yet unknown thyroid disorders such as goitre, inhomogeneous thyroid pattern, nodules, hypoechogenicity and anti-TPOAb seropositivity. Reference intervals for serum TSH, FT(3), and FT(4) were 0.25-2.12 mIU/L, 3.8-7.0 pmol/L, and 8.3-18.9 pmol/L, respectively. Reference serum TSH levels were not comparable to the reference values that were recently established for the U.S. population and most reference values slightly differed from the reference values provided by the manufacturers.


CONCLUSIONS
The reference ranges of thyroid function tests in this formerly iodine-deficient region are distinct from the reference ranges that were established in areas with iodine sufficiency. Creating a reference population in the present setting should include thyroid ultrasound in order to exclude yet undiagnosed thyroid disorders.
Völzke
Henry
H
Institute of Epidemiology and Social Medicine, Ernst Moritz Arndt University Greifswald, Germany. voelzke@uni-greifswald.de
Alte
Dietrich
D
Kohlmann
Thomas
T
Lüdemann
Jan
J
Nauck
Matthias
M
John
Ulrich
U
Meng
Wieland
W
D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood; D005260:Female; D005843:Geography; D005858:Germany / Q000453:epidemiology; D006042:Goiter / Q000453:epidemiology; D006801:Humans; D007453:Iodide Peroxidase / Q000276:immunology; D007455:Iodine / Q000172:deficiency*; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D013960:Thyroid Function Tests; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000276:immunology*; D016606:Thyroid Nodule / Q000453:epidemiology; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*; D014463:Ultrasonography
D001323:Autoantibodies; D014284:Triiodothyronine; D013972:Thyrotropin; D007455:Iodine; D007453:Iodide Peroxidase; D013974:Thyroxine