Role of Midkine in Predicting Malignancy in Patient with Solitary Thyroid Nodule

Background: Solitary thyroid nodules are a common clinical problem. None of sonographic features is sufficient to discard or detect malignancy efficiently. Midkine is a novel heparin-binding growth factor, plays critical roles in carcinogenesis. In this study, we aimed to evaluate serum midkine levels in patients with solitary thyroid nodules to predict malignancy. Methods: A total of 100 patients who had solitary thyroid nodules were enrolled in the study. Serum midkine levels were measured. Fine needle aspiration cytology was done to all nodules (25 suspicious/ malignant and 75 benign). Results: Serum midkine levels were significantly higher in patients who had nodules with the following sonographic features; hypoechoic nodules compared to isoechoic and hyperechoic nodules (P=0.024), nodules with microcalcification compared to nodules with macrocalcification or without calcification (P = 0.011), nodules with irregular borders compared to nodules with regular borders (P = 0.014) and nodules more than 2 cm in length than shorter ones (P = 0.011). Serum midkine levels were also higher in nodules with absent halo compared to those with clear halo but with no significant difference (P = 0.660). Also, levels of serum medikine were significantly higher in suspicious/ malignant nodules than in benign nodules (P < 0.001). Conclusion: Serum midkine can predict malignancy in solitary thyroid nodule and also well correlated with sonographic features of thyroid nodules. We suggest that midkine levels may serve as a novel biochemarker in association with sonographic features in evaluation of solitary thyroid nodules.