Dual-phase 99mTc-MIBI scintigraphy to assess calcimimetic effect in patients on haemodialysis with secondary hyperparathyroidism

OBJECTIVE To evaluate the effect of calcimimetics with 99mTc-methoxy-isobutyl-isonitrile (MIBI) parathyroid scintigraphy in secondary hyperparathyroidism. METHODS This prospective study included 30 consecutive haemodialysis patients with inadequately controlled secondary hyperparathyroidism despite standard medical treatment. Patients were given a single daily oral dose of 30 mg of cinacalcet. A baseline and 1-year follow-up dual-phase 99mTc-MIBI scintigraphy were performed. 99mTc-MIBI uptake in each parathyroid gland was graded on a semiquantitative scale (scoring 0-3). RESULTS Twenty-one of the 30 patients responded to cinacalcet (70%). Abnormal positive glands were identified by 99mTc-MIBI scintigraphy in 27 out of 30 patients (53 glands). The sensitivity and specificity of 99mTc-MIBI in detecting cinacalcet response were 90 and 89%, respectively. The mean baseline and posttreatment grades of 99mTc-MIBI uptake were 2.9 ± 1.8 and 1.1 ± 1.2 (P < 0.0001) in the responder group and 3.1 ± 2.1 and 3.9 ± 2.2 (P = ns) in the nonresponder group. CONCLUSION 99mTc-MIBI scintigraphy is useful in monitoring the response to calcimimetics in secondary hyperparathyroidism.