Serum thyrotropin and free thyroxine reference ranges as defined in a disease-free sample of French middle-aged adults.
BACKGROUND
The goal of this study was to provide reference ranges for thyrotropin (TSH) and free thyroxine (fT(4)) based on data collected from a disease-free sample of French middle-aged adults.


METHODS
A total of 3218 subjects participating in the Supplémentation en Vitamines et Minéraux Antioxydants (SU.VI.MAX) study had measurements for TSH, fT(4) and urinary iodine concentrations. Thyroid volume and structure were evaluated using standardized ultrasonography. We selected a disease-free sample which included 2338 subjects (1313 females aged 35-60 years and 1025 males aged 45-60 years) with normal thyroid imaging, no previously reported thyroid disease or use of thyroid medication, and no risk factors for thyroid dysfunction. Distribution of TSH and fT(4) was estimated in males and females.


RESULTS
The median (central 95% range) TSH serum concentrations for females were 1.79 mU/L (0.29-5.21 mU/L) for ages 35-44 years and 1.98 mU/L (0.27-6.94 mU/L) for ages 45-60 years (p<0.0001, for age). The median (central 95% range) for males 45-60-year-old was 1.63 mU/L (0.28-4.54 mU/L) (p<0.0001, for sex). Sex- and age-specific mean fT(4) concentrations did not differ significantly (p=0.06) between males and females and (p=0.08) between female age groups. However, median fT(4) concentrations between 45-60-year-old males and females differed (p<0.001).


CONCLUSIONS
In middle-aged adults, the TSH distribution was associated with gender and, among females, with age. Stratification according to gender and age should be considered when TSH ranges are used in the diagnosis, treatment and monitoring of thyroid disease. Clin Chem Lab Med 2009;47:1497-505.
Estaquio
Carla
C
Unité de Surveillance et d'Epidémiologie Nutritionnelle, Institut de Veille Sanitaire, Université Paris 13, Cnam, Centre de Recherche en Nutrition Humaine Ile-de-France, Bobigny, France.
Valeix
Pierre
P
Leenhardt
Laurence
L
Modigliani
Elizabeth
E
Boutron-Ruault
Marie-Christine
MC
Chérié-Challine
Laurence
L
Legrand
Marguerite
M
Hercberg
Serge
S
Castetbon
Katia
K
D004311:Double-Blind Method; D005260:Female; D005602:France; D006801:Humans; D008297:Male; D008875:Middle Aged; D010919:Placebos; D012016:Reference Values; D013961:Thyroid Gland / Q000000981:diagnostic imaging; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D014463:Ultrasonography
D010919:Placebos; D013972:Thyrotropin; D013974:Thyroxine