C-Reactive Protein Level can be a Better Indicator than Erythrocyte Sedimentation Rate in Assessing the Severity of Inflammation and Guiding Glucocorticoid Therapy in Subacute Thyroiditis

BACKGROUND: Despite the widespread use of several diagnostic tests in subacute thyroiditis (SAT), their usage remains largely subjective. C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) are useful indicators of inflammation in patients with SAT. The purpose of this study was to compare the scope for utilising CRP and ESR objectively in deciding the requirement of glucocorticoid therapy. METHODS: A total of 28 patients with SAT were included in this study. Serum CRP and ESR were measured in all the patients. The characteristics of these tests were assessed firstly by using previously accepted positivity criterion for the particular diagnostic test. The area under the receiver operating characteristics (ROC) curve was obtained to provide an index of the overall discriminative ability of both tests. RESULTS: Fifteen out of 28 patients were found to have features of significant thyroid inflammation eventually requiring glucocorticoid based on the current recommendations. The mean CRP value was significantly higher in patients requiring glucocorticoids. The ROC curves indicated that the optimal positivity criterion was 19.3 mg/L for the CRP level and 46 mm at the 1(st) hour for ESR. CRP with a sensitivity of 0.67, a specificity of 0.92, a positive likelihood ratio of 8.67, and an accuracy of 0.64 appeared better than ESR, which showed a sensitivity of 0.93, a specificity of 0.53, a positive likelihood ratio of 2.02, and an accuracy of 0.60. CONCLUSIONS: The serum CRP level provided a clear advantage over ESR in the assessment of the severity of inflammation before initiation of glucocorticoid therapy in SAT. However, a well-powered study is needed to examine the clinical relevance of such a role for CRP in thyroidology.