Urinary iodine and sodium concentration and thyroid status in the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

OBJECTIVES: To evaluate urinary iodine concentration (UIC) in civil servants aged 35-74 years of the Brazilian Study of Adults Health (ELSA-Brasil) to analyze its relationship with sociodemographic, clinical risk factors, lifestyle, urinary Na and thyroid status. DESIGN: Cross-sectional study in six Brazilian cities. METHODS: This analysis included 792 participants with information about urinary iodine concentration (UIC). Thyroid status was defined by serum levels of TSH/FT4 and the current use of antithyroid drugs for treatment of overt hyperthyroidism or levothyroxine to treat overt hypothyroidism. The determination of UIC was carried out with an inductively coupled plasma mass spectrometer (ICP-MS) and was expressed as median with Interquartile Range (IQR). RESULTS: In 792 participants, thereof 52% women, mean age was 51.9 (9.0) years. The median UIC was 219 (IQR, 166-291) for all persons studied, thereof 211 (IQR, 157-276) for women and 231 (IQR, 178-304) for men. According to the WHO classification, for all persons studied, 60% had more than adequate iodine-supply (UIC ≥200 µg/L), 37% were adequately supplied (UIC 100-199 µg/L) and <3% had a deficient iodine status (<100 µg/L). In the 35-44-year age strata, which includes women of childbearing age, 23.2% of women presented less than 150 µg/L of UIC. No differences in UIC were detected according to thyroid status. (P = 0.39) The correlation between Ur-Na and UIC showed a Spearman coefficient of 0.52 (P < 0.0001) and it was also found an association of Ur-Na with UIC: Beta of 1.76 (95% Confidence Interval (95% CI): 1.01 to 2.51. The urinary Na concentration showed a synergy with the UIC, that means medians of 57, 72, 107 and 141 mmol Na/L urine (P < 0.001) in the groups with the four UIC classes according to the WHO grading mentioned above. The very low Na content in the persons exhibiting <100 µg/L UIC seems to reflect also a higher urine volume due to the frequent use of diuretics. The strong relationship between the urinary Na concentration and the UIC points to a dependence of the UIC on the individual consumption of iodized salt, which should be more considered in future studies. The strong relationship between the urinary Na concentration and the UIC points to a dependence of the UIC on the individual consumption of iodized salt, which should be more considered in future studies. CONCLUSIONS: Euthyroid persons were dominating by more than four fifths and no significant association was found between UIC and thyroid status. Although most of the persons studied present more than adequate iodine intake it was observed that nearly a quarter of women in childbearing age are iodine deficient.

Incidence of thyroid diseases: Results from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

OBJECTIVE: To evaluate incidence of subclinical and overt hyperthyroidism and hypothyroidism. METHODS: The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) is a prospective cohort study of 15,105 civil servants, examined at baseline and over a 4-year follow-up. This analysis included 9,705 participants with normal thyroid function at baseline, follow-up information about thyroid function and with no report of using drugs that may interfere in the thyroid function. Thyroid function was defined by TSH/FT4 levels or routine use of thyroid hormones/anti-thyroid medications. Annual and cumulative (over 4-year) incidence rates were presented as percentages (95% Confidence Intervals). RESULTS: The incidence of all overt and subclinical thyroid disease was 6.7% (1.73%/year): 0.19% for overt hyperthyroidism (0.048%/year), 0.54% for subclinical hyperthyroidism (0.14%/year), 1.98% for overt hypothyroidism (0.51%/year), and 3.99% for subclinical hypothyroidism (1.03%/year). The incidence of all thyroid diseases was higher in women, when compared to men, with a low women:men ratio (1.36). For Blacks the highest incidence was for overt hyperthyroidism, while for Whites, the highest incidence was for overt hypothyroidism. However, the highest incidence of overt hyperthyroidism was detected in Asian descendants. The presence of antithyroperoxidase antibodies at baseline was associated with higher incidence of overt thyroid diseases. CONCLUSION: These results showed a high incidence of hypothyroidism, which is compatible with a country with a more-than-adequate iodine intake. The low women:men ratio of the incidence of thyroid dysfunction highlights the importance of the diagnosis of thyroid diseases among men in Brazil.

Associations of dairy intake with glycemia and insulinemia, independent of obesity, in Brazilian adults: the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

BACKGROUND: Inverse associations between dairy intake and the risk of type 2 diabetes have been shown, but more studies are needed, especially from low- and middle-income countries. OBJECTIVE: The objective was to describe the association between dairy products and direct measures of glycemic status in adults without known diabetes. DESIGN: The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) includes 15,105 adults, aged 35-74 y, enrolled from universities and research institutions in 6 Brazilian capital cities. We excluded participants with a known diabetes diagnosis, cardiovascular diseases, and cancer. Dairy consumption was assessed by a food-frequency questionnaire, and we computed servings per day for total and subgroups of dairy. Associations with fasting blood glucose (FG) and fasting insulin, 2-h postload glucose (PG), 2-h postload insulin (PI), glycated hemoglobin (Hb A1c), and homeostasis model assessment of insulin resistance (HOMA-IR) were assessed through multivariable linear regression analysis with adjustment for demographic characteristics, behavioral risk factors, other dietary factors, and anthropometric measurements. RESULTS: The sample size after exclusions was 10,010. The intake of total dairy was inversely associated with FG (linear ß for dairy servings/d = -0.46 ± 0.2 mg/dL), PG (-1.25 ± 0.5 mg/dL), PI (-1.52 ± 0.6 mg/dL), Hb A1c (-0.02 ± 0.0%), and HOMA-IR (-0.04 ± 0.0) after adjustment for all covariates (P < 0.05 for all). The findings were consistent across categories of sex, race, obesity status, and dairy fat amount (reduced-fat vs. full-fat dairy). Fermented dairy products showed particularly strong inverse associations with the outcomes, with adjusted differences for a 1-serving/d increment of -0.24 (95% CI: -0.46, -0.02) mg/dL for FG, -0.86 (-1.42, -0.30) mg/dL for PG, and -0.01% (-0.02%, 0.00%) for Hb A1c. Myristic acid was the only nutrient that appeared to mediate the association between dairy intake and glycemia. CONCLUSION: Dairy intake, especially fermented dairy, was inversely associated with measures of glycemia and insulinemia in Brazilian adults without diagnosed diabetes. This trial was registered at clinicaltrials.com as NCT02320461.