Effect of High Normal Thyroid Stimulating Hormone Levels on Lipid Parameters in Non-diabetic Subjects

Aim: To investigate relationship between serum TSH and lipid parameters in subjects with different levels of TSH.

Study Design: Cross-sectional study.

Place and Duration of Study: Clinical Biochemistry Department of Kasturba Medical College, Hospital Mangalore, between January 2014 to June 2014.

Methodology: 348 subjects were screened of which 194 were selected. Lipid parameters, TSH, T3, T4 and glycemic status were determined. Association between TSH and serum lipids were studied by categorizing subjects into three groups based on their thyroid status. Group 1 [TSH= 0.27-2.5 mIU/L], Group 2 [TSH= 2.6-4.12 mIU/L] and Group 3 [TSH= 4.13-9.9mIU/L].Statistical analysis was performed by ANOVA followed by Tukey’s multiple comparison test. The relationships between TSH and different parameters were evaluated by Pearson’s correlation analysis.

Results: TSH showed a significant positive linear correlation with total cholesterol (r=0.288; P = 0.001), Triglycerides (r=0.129; P=0.016), LDL cholesterol (r=0.305; P =0.001) and negative correlation with HDL (r = - 0.129; P=0.750). Increasing TSH showed a consistent linear association with altered lipids quite evident from the uppermost part of the reference range that is considered clinically normal and there on.

Conclusion: A subtle variations of TSH alone in clinically normal thyroid state can alter serum lipids and hence asserts the role of TSH in maintaining lipid homeostasis.