Predictive Significance of High Sensitive C-reactive Protein in Subclinical Hypothyroidism: A Prospective Observational Study

Abstract

Introduction: Subclinical hypothyroidism (SCH) is more common than overt hypothyroidism. It is associated with increased risk of dyslipidaemia, Coronary Artery Disease (CAD), left ventricular diastolic dysfunction, peripheral vascular diseases and chronic inflammation. Chronic inflammation plays a significant role in clinical manifestations and systemic organs injury in hypothyroidism. High-sensitivity C-reactive Protein (hs-CRP) is a pentameric protein produced by the liver, and its level increases in response to inflammation. There are not much studies to prove that chronic inflammation could be a major risk factor for conversion of subclinical hypothyroidism in to overt hypothyroidism. Aim: To study the role of chronic inflammation as a risk factor for conversion of SCH in to overt hypothyroidism with lipid abnormalities and cardiac dysfunction, by using inflammatory markers like hs-CRP. Materials and Methods: This prospective observational study was conducted at KR hospital, Mysuru, Karnataka, India, from August 2019 to September 2020 among 112 subjects of subclinical hypothyroidism attending the Outpatient Department. The data regarding detailed history and clinical examination were collected from all the patients. Investigations such as Thyroid Stimulating Hormone (TSH), Triiodothyronine (T3), Thyroxine (T4) levels hs-CRP level, lipid profile, Electrocardiogram (ECG), Random Blood Sugar (RBS), Renal Function Test (RFT), Complete Blood Count (CBC), 2D-Echocardiography were done on day one and after 6 months. The data analyses was done by using the Chi-square test or Fisher’s-exact test. The factors which were significant as per the Chi-square test were selected and subjected to multivariate analysis. Results: The number of cases of subclinical hypothyroidism (hs-CRP >3 mg/L, mean TSH=9.1±2.1 microIU/mL) at first day were 23 (20.53%). At the end of 6 months those converted to overt hypothyroidism (mean TSH=11.4±2.3 microIU/mL) were 14 (12.5%) patients. The patients with hs-CRP of >3 mg/L, with mean TSH of 11.4±2.3 microIU/mL at the end of 6 months of study, had left ventricular dysfunction in 68 (60.07%) patients. In the same group, the low-density lipoprotein cholesterol >160 mg/dL was found in 60 (53.57%) patients and serum triglycerides level >200 mg/dL was found in 51 (45.53%) patients (p-value <0.05). Conclusion: Chronic inflammation is one of the major risk factor for conversion of subclinical hypothyroidism in to overt hypothyroidism with associated cardiovascular dysfunction and dyslipidaemia.