Interrelationship of High Sensitive C Reactive Protein and Thyroperoxidase Antibody Levels with Dyslipedemia in Subclinical Hypothyroidism and Overt Hypothyroidism

Background and Aims: Antibodies against thyroperoxidase (TPO-Ab) and cholesterol levels are raised in overt hypothyroidism (OH) along with an increase of hsCRP, an early indicator of low grade inflammation. However, hypercholesterolemia and dyslipedemia has been found inconsistently in subclinical hypothyroidism (SCH) in different regions. The present study aimed at elucidating the relative importance of hsCRP and TPO-Ab with altered lipid parameters in both SCH and OH patients in this Region.

Study Design: Hospital-based case control study.

Methodology: Lipid parameters and hsCRP were measured in and TPO-Abs positive 35 OH and 35 SCH patients and 30 control subjects. Serum TSH, free T4, TPO-Ab, hsCRP levels and lipid parameters were measured by ELISA and standard photometric assays respectively. Post hoc ANOVA, bivariate correlation and multiple linear regression assays were used for analysing the differences between mean values, strength of association between study variables and dependence of LDL cholesterol(LDLc) on hsCRP and TPO-Ab levels.

Results: Mean LDLcandHDLc were significantly increased and decreased respectively in both OH (146 ± 11.4; 29.5 ± 4.6); and SCH (132.4 ± 8.4; 37.6 ± 4.1) when compared with the control groups (90.8 ± 8.1; 44.4 ± 7.7) in graded manner (P < 0.001 between all groups).A similar rise in hsCRP levels (1.14 ± .32 in control, 2.22 ± .40 in SCH and 3.5 ± 1.0 in OH; P < 0.001 between all groups) was observed. Elevation in TPO-Ab levels in OH and SCH groups were significant only in comparison with the control groups (21.2 ± 5.5 in control, 44.8 ± 15 in SCH and 52.4 ± 16.7 in OH group; P < 0.001 against control group for both SCH and OH, but .07 between SCH and OH groups). LDLc was directly correlated with both TPO-Ab and hsCRPlevels in both groups. However, hsCRP levels showed better predictor effect on LDLc levels in both groups (β = .484 and .498; P = .002 and .003 for the OH and SCH respectively) in comparison to TPO-Ab (β = .281 and .200; P = .059 and .206 for the OH and SCH respectively).

Conclusion: Our findings specify the contributory roles of a low grade inflammatory state on altered LDLc metabolism that culminates in atherosclerosis in early thyroid diseases. It is also evident that hsCRP is a better indicator of it compared to TPO-Ab in even TPO-Ab positive hypothyroid patients. As in the OH group, hsCRP measurement in SCH can also help in initiating restrictive measures to minimise its further progression in OH conditions.