| Objective:To investigate the prevalence of thyroid dysfunction and positive thyroid specific antibodies in a community-based population of Nanjing.Methods:Community-living subjects, aged 20 years or older, who had lived at Nanjing for at least 5 years were sampled by a randomized clustered sampling method based on national population census data. The following cross-sectional survey was conducted from Dec. 2009 to Jun. 2010. The number of residents for the present study was 1540 after strict screening. A questionnaire was administered to each participant eliciting personal information. Height, weight, blood pressure and some other basal parameters of the subjects were also collected. Fasting serum and urine were sampled and thyroid stimulating hormone (TSH), thyroid peroxidase antibodies (TPOAb), thyroglobulin antibodies (TgAb) and urine iodine (UI) excretion were measured. Serum free thyroxine (FT4) and free triiodothyronine (FT3) were tested if abnormal thyroid-stimulating hormone (TSH) had been detected. Twenty samples of the table salt, drinking water and 80 fasting urine samples from children in the community were obtained to test the iodine levels.Results:(1) We found 50 subjects with self-reported previous thyroid diseases, accounting for 3.2% of total population, the percentage among women is 5.25 times that of men. Twenty-eight percent had an abnormal serum TSH level in this survey and most of these individuals (93.3%) were women, among whom 62% were taking thyroid medications. The percentages of TPOAb- and TgAb-positive subjects were 48.0% and 42.0%, respectively, No differences were observed between males and females.(2) The prevalence of thyroid dysfunction in 1490 subjects was 6.6% when excluding subjects with self-reported previous thyroid diseases which was significantly higher among women (8.0%) than men (4.9%) (P=0.001). Overt hyperthyroidism was found in 1.1% of the thyroid disease-free population and subclinical hyperthyroidism in 1.5%. Overt hypothyroidism was found in 0.3% and subclinical hypothyroidism in 3.7%. Only the prevalence of subclinical hypothyroidism was higher in women than in men (P=0.001), and also increased with age only in females (P=0.04).(3) In 1490 disease-free individuals, TPOAb was positive alone in 9.3%, and TgAb was positive alone in 10.8%. Both of them were detected in 5.6%. There were significantly more females than males with detectable TPOAb, TgAb or both (P<0.001); the prevalence of positive TPOAb increased with age in women (P=0.03). Any kind of thyroid dysfunction could be found more prevalent in antibody-positive subjects (TPOAb, TgAb or either of them) than in negative ones (P<0.001). The percentage of individuals with positive TPOAb or TgAb was 1ower in the euthyroid group than hyperthyroid or hypothyroid groups (P<0.01) .(4) Median serum TSH concentration (2.5~97.5 percentiles) was 2.49 mU/L (0.69-7.07) for the disease-free population (n=1490), with no signi?cant trend towards a rise in TSH concentrations with increasing age in either sex. Serum TSH levels (median, 2.5~97.5 percentiles) were higher in women than in men (2.78, 0.70~7.87 mU/L vs. 2.15, 0.69~6.11 mU/L; P<0.001). Females had significantly higher serum TSH than males in each age group aged 59 yr and below. TSH was positively related to the TPOAb and TgAb levels (P<0.01); negatively related to urinary iodine concentration (P=0.009); the correlations were also significant after adjustment for age and sex (P<0.05).Conclusions:(1) The percentage of diagnosed thyroid diseases was much higher in women than in men and thyroid dysfunction was not controlled appropriately.(2) The prevalence of subclinical hypothyroidism and positive antibodies were higher in women than in men, both of subclinical hypothyroidism and positive TPOAb had an increasing tendency only in females.(3) Serum TSH levels were higher in women than in men,though a rising trend with increasing age was not found in either sex. Positive thyroid antibodies were closed correlated with thyroid dysfunction. Objective:To investigate the correlation of iodine nutrition with thyroid function or thyroid antibodies in a community-based population of Nanjing.Methods:Community-living subjects, aged 20 years or older, who had lived at Nanjing for at least 5 years were sampled by a randomized clustered sampling method based on national population census data. The following cross-sectional survey was conducted from Dec. 2009 to Jun. 2010. The number of residents for the present study was 1540 after strict screening. A questionnaire was administered to each participant eliciting personal information. Height, weight, blood pressure and some other basal parameters of the subjects were also collected. Fasting serum and urine were sampled and thyroid stimulating hormone (TSH), thyroid peroxidase antibodies (TPOAb), thyroglobulin antibodies (TgAb) and urine iodine (UI) excretion were measured. Serum free thyroxine (FT4) and free triiodothyronine (FT3) were tested if abnormal thyroid-stimulating hormone (TSH) had been detected. Twenty samples of the table salt, drinking water and 80 fasting urine samples from children in the community were obtained to test the iodine levels.Results:(1) This community-based study was conducted in 1540 adults [701 men (45.5%) and 839 women (54.5%), aged from 20 to 92; mean age: 44.6±15.3]. The iodine levels of drinking water and table salt being consumed in the home at the moment of the visit were 3.72±0.97 ug/l and 31.9±3.42 mg/kg, respectively. Median urine iodine concentration was 282.1 ug/l in children and 239.4 in adults. No differences in urine iodine levels were found between males (242.1 ug/l) and females (236.6 ug/l).(2) In 1490 subjects without previous thyroid diseases, urine iodine (UI) concentration had no relation to the TPOAb and TgAb levels; though it was negatively related to TSH (P<0.01), which was also significant after adjustment for age, sex, TPOAb and TgAb (P<0.05).(3) According to urine iodine concentration, 1490 subjects without previous thyroid diseases were divided into iodine-deficient (<100 ug/L), adequate (100-199 ug/L), more than adequate (200-300 ug/L) or excessive groups (>300 ug/L). No differences were observed in mean TSH concentrations or prevalence of any kind of thyroid dysfunction and positive antibodies among the four groups.(4) No differences in median urine iodine concentration were found between groups with thyroid dysfunction (hypo or hyper) and normal TSH concentrations or between positive and negative antibody groups.(5) According to urine iodine concentration, 1490 subjects without previous thyroid diseases were divided into two groups, <200 ug/L group or >200 ug/L group, UI>200 ug/L was not significantly associated with thyroid dysfunction (hyper- or hypothyroidism), positive TPOAb or TgAb.Conclusions:(1) The level of iodine intake of residents in Nanjing during this community-based survey was more than adequate.(2) Urine iodine concentration was not significantly associated with thyroid dysfunction or positive antibodies among the studied subjects. |
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