Ultrasound-based scores as predictors for nodular hyperplasia in patients with secondary hyperparathyroidism: a prospective validation study.

Purpose: Former studies evaluated echostructural and vascular patterns in ultrasound of the parathyroid gland to identify nodular hyperplasia in patients with secondary hyperparathyroidism due to chronic kidney disease. This prospective study aims to externally validate suggested ultrasound classifications.
Methods: Parathyroid glands of 27 patients with secondary hyperparathyroidism undergoing parathyroidectomy were prospectively analyzed. Ultrasound including Doppler imaging was performed 1 day prior to surgery. Ultrasound data were available for 70 parathyroid glands. Echostructural and vascular scores according to previous studies were applied calculating the area under the receiver operating characteristic curve (AUROC). Overall correctness, sensitivity, and specificity of the investigated scores were assessed with the Youden index method.
Results: The Doppler score introduced by Vulpio and colleagues based on characteristic blood flow patterns in parathyroid glands showed an AUROC of 0.749 for the prediction of nodular hyperplasia with an overall correctness of 72.8%. Other ultrasound classifications based on blood flow patterns, as well as echostructure of the parathyroid gland displayed AUROCs of <0.700, thus, lacking sufficient capability as a prognostic model. Overall correctness of prediction varied from 53.8 to 55.9%.
Conclusions: The Vulpio Doppler score for the prediction of nodular hyperplasia in patients with secondary hyperparathyroidism was externally validated for the first time. Other ultrasound scores fail as prognostic models in this study population. Doppler sonography of the parathyroid gland has prognostic capability to identify nodular hyperplasia as surrogate marker for patients with secondary hyperparathyroidism indicating the need for ablative or surgical treatment when failing conservative therapy.