Thyroglobulin as a marker of iodine nutrition status in the general population.
OBJECTIVE
The iodine status of a population is traditionally evaluated by either urinary iodine (UI) excretion or by some measure of thyroid volume and the prevalence of goitre. In this prospective study of a mandatory iodization programme, we aimed to evaluate serum thyroglobulin (Tg) as a marker of iodine status in the population.


METHODS
Two identical cross-sectional studies were performed before (1997-1998, n=4649) and after (2004-2005, n=3570) the initiation of the Danish iodization programme in two areas with mild and moderate iodine deficiency. Serum Tg was measured from blood samples. Thyroid volume was measured by ultrasonography.


RESULTS
Before iodization, the median serum Tg was considerably higher in moderate than in mild iodine deficiency. Iodization led to a lower serum Tg in all examined age groups. The marked pre-iodization difference in Tg level between the regions was eliminated. The prevalence of Tg above the suggested reference limit (40 microg/l) decreased from 11.3 to 3.7% (P<0.0001). Using bootstrapping, we demonstrated a higher efficacy of Tg than of thyroid volume to show a difference between pre- and post-iodization values.


CONCLUSIONS
We found serum Tg to be a suitable marker of iodine nutrition status in the population. The results may suggest that the Danish iodization programme has led to a sufficient iodine intake, even if the median UI excretion is still marginally low according to WHO criteria.
Vejbjerg
Pernille
P
Department of Endocrinology and Gastroenterology, Bispebjerg University Hospital, Bispebjerg Bakke 23, 2400 Copenhagen NV, Denmark. pernille.vejbjerg@regionh.dk
Knudsen
Nils
N
Perrild
Hans
H
Laurberg
Peter
P
Carlé
Allan
A
Pedersen
Inge Bülow
IB
Rasmussen
Lone B
LB
Ovesen
Lars
L
Jørgensen
Torben
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D003430:Cross-Sectional Studies; D003677:Deficiency Diseases / Q000097:blood / Q000175:diagnosis* / Q000178:diet therapy / Q000453:epidemiology; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D007455:Iodine / Q000008:administration & dosage* / Q000172:deficiency; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D011153:Population; D015995:Prevalence; D011379:Prognosis; D013954:Thyroglobulin / Q000097:blood*; D055815:Young Adult
D015415:Biomarkers; D013954:Thyroglobulin; D007455:Iodine