Significant role of serum CRP in differentiating inflammatory from non-inflammatory causes of thyrotoxicosis

Background: C-reactive protein (CRP), which is a marker of inflammation, has not been widely studied in inflammatory thyroid disorders particularly in sub-acute thyroiditis (SAT). Aim: This study was aimed to find the significance of CRP level rise in patients with SAT and compare that to the rise in erythrocyte sedimentation rate (ESR), a gold standard laboratory parameter in establishing the diagnosis of SAT. Materials and Methods: Serum CRP levels were measured at initial presentation in 28 subjects with SAT(12 male, 16 female, age (Mean +SD) 37.96 ±8.5 years),and 19 patients with Graves′ disease (2 male, 17 female, age [Mean +SD] 36.8 ±16.5 years) as controls. Erythrocyte sedimentation rate (ESR) was measured in all 28 patients with SAT by Westergrens′ method. Either Tc 99 nucleotide thyroid scan or high resolution ultrasonography (HR-USG) was performed to differentiate SAT from Graves′ disease.Fine needle aspiration cytology (FNAC) of thyroid was performed selected patients. Results: Serum CRP level was high in 61% of SAT patients but in none of the Graves′patients. Mean (SEM) (90%CI) serum CRP level (mg/L) was also significantly higher (P