Obesity and thyrotropinemia: Association in Indian adults

Abstract

Aim: Obesity affects pituitary thyroid axis resulting in elevated thyroid stimulating hormone (TSH) levels. The objective of our study was to investigate whether there is an association between body mass index (BMI) and TSH in euthyroid and subclinical hypothyroid obese persons and to compare serum TSH levels among obese and overweight subjects presenting to our obesity clinic. Materials and Methods: A total of 150 consecutive subjects aged between 18 and 60 years presenting to our obesity clinic were enrolled. Patients were divided in three groups, group 1: overweight (BMI: 23- 24.9 kg/m 2 , n = 65), group 2: class I obese (BMI: 25-29.9 kg/m 2 , n = 58), and group 3: class II obese (BMI: 30-34.9 kg/m 2 , n = 27). All subjects underwent thyroid profile along with other routine tests. Fisher's exact test, Mann-Whitney U test and Pearson's correlation were used for statistical analysis. P value <0.05 was considered significant. Results: Elevated TSH level (5-10 μIU/ml) with normal T 3 and T 4 was seen in 12/65 overweight, 19/58 class I obese (P = 0.614) and 12/27 of class II obese subjects (P = 0.529). Mean TSH levels were higher in subjects with higher BMI (group 1: 3.2 ± 3.1, group 2: 3.6 ± 2.2, group 3: 3.8 ± 2.8). Over all TSH showed no correlation with BMI (r = 0.0018, P = 0.872). Conclusion: Though higher BMI leads to higher TSH levels in our series, we could not find any significant relation between severity of obesity and TSH levels. Further large scale data from population is required to confirm or negate our finding.