Abstract
Objectives: High TSH levels often observed in overweight subjects are associated with metabolic
risk. Thyroid hormones which are involved in fat and carbohydrates metabolism are
more rarely studied; their blood levels were measured to more precisely explain the
relationships between thyroid function and obesity, in healthy overweight youth. This
correlation was studied at baseline and during follow-up of some patients.
Materials/Methods: Data collected were BMI and BMI z score, thyroid hormones (TSH, fT4, fT3), fasting
blood glucose, HOMA-IR, lipids (triglycerides, HDL and LDL cholesterol), transaminase
activity, fibrinogen, leptin, IGF-I; body composition (biphotonic absorptiometry).
Data collected in a sample of the group after 6–18 months of medical intervention
could also be studied.
Results: At baseline, 13% of the 528 obese subjects (55% girls; 11.3±2.4 years, range 4.1-17.9;
BMI z score: 5.4±2.4) had TSH>4mUI/l; fT3 levels were associated with age and transaminase
activity; using multivariate regression analysis, with z-score and age as covariates,
fT4 showed correlations with TSH, insulin, HOMA IR, blood lipids, and fibrinogen.
No correlations were found with leptin, iodine excretion, IGF-I.
In 79 patients followed for 52±15 wk (45% girls; age range 8–18.3 years), univariate
regression showed a positive correlation between changes in TSH and HOMA-IR, and between
changes in fT4 and HDL. Multivariate regression analysis with z score as covariate
showed that baseline TSH was associated with negative changes in HOMA-IR.
Conclusions: Increased TSH may be predictive of a decrease in insulin resistance, it should be
measured with thyroid hormones; fT4 was associated with a low metabolic risk. Changes
in thyroid function could protect against the occurrence of obesity-associated metabolic
diseases.
Key words
obesity - TSH - T4 - T3 - metabolic syndrome
