Subject:
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EBP 1: Determinants in Health and Disease IGMD 5: Health aging / healthy living IGMD 6: Hormonal regulation IGMD 7: Iron metabolism N4i 1: Pathogenesis and modulation of inflammation NCEBP 14: Cardiovascular diseases NCEBP 1: Molecular epidemiology NCEBP 2: Evaluation of complex medical interventions ONCOL 1: Hereditary cancer and cancer-related syndromes ONCOL 3: Translational research ONCOL 5: Aetiology, screening and detection UMCN 1.2: Molecular diagnosis, prognosis and monitoring UMCN 5.1: Genetic defects of metabolism UMCN 5.2: Endocrinology and reproduction |
Organization:
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Endocrinology Health Evidence Clinical Chemistry Chemical Endocrinology |
Former Organization:
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Epidemiology, Biostatistics & HTA
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Abstract:
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BACKGROUND: We present a large European population-based study of thyroid function, performed in a population with longstanding borderline sufficient iodine intake. METHODS: The Nijmegen Biomedical Study is a population-based survey conducted in the eastern part of The Netherlands. Randomly selected inhabitants received a postal questionnaire on lifestyle and medical history, which was filled out by 9371 individuals (41.7%). We measured serum thyroid-stimulating hormone (TSH), free thyroxine (FT4), and anti-thyroperoxidase antibodies (TPOAbs) in 6434 responders. A reference population of 5167 individuals was selected by excluding those at risk for thyroid disease. RESULTS: Overt thyrotoxicosis was found in 0.4% of the total population and subclinical thyrotoxicosis in 0.8%. Overt hypothyroidism was found in 0.4% and subclinical hypothyroidism in 4.0%. In individuals older than 60 years, mean FT4 concentrations increased with age. Mean TSH decreased with age, from 1.46 mIU/L at 18-24 years to 1.07 mIU/L after 85 years. The mean TSH in the total population did not differ from the mean TSH in the reference population; the exclusion of those at risk for thyroid disease, however, lowered the upper limit of the TSH reference interval considerably. In the total population, 8.6% of males and 18.5% of females had positive TPOAbs. The presence of TPOAbs was associated with abnormally high and low TSH concentrations. CONCLUSION: In inhabitants of the eastern part of The Netherlands, serum TSH gradually decreases with age, whereas after age 60, serum FT4 increases, possibly because of the development of thyroid autonomy after longstanding borderline sufficient iodine intake.
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