Influence of Parathyroidectomy on Bone Calcium Concentration: Evaluation with Spectral CT in Patients with Secondary Hyperparathyroidism Undergoing Hemodialysis-A Prospective Feasibility Study

Abstract

Purpose To use spectral computed tomography (CT) to evaluate the influence of parathyroidectomy (PTX) on calcium concentration in trabecular bone and cortical bone in patients undergoing hemodialysis with secondary hyperparathyroidism. Materials and Methods This study was performed with institutional review board approval. Written consent was obtained from each patient. Thirty-eight men (mean age ± standard deviation, 55.69 years ± 8.05; range, 42-72 years) undergoing maintenance hemodialysis who underwent PTX and 40 patients (mean age, 56.71 years ± 9.53; range, 45-74 years) who did not undergo PTX received prospective follow-up for 2 years. Bone calcium concentration was measured in the cortical compartment of the bilateral proximal femur and the medullary compartment of the lumbar vertebral bodies (L1 through L3) on the basis of calcium-based material decomposition images of a spectral CT examination. The differences between baseline and end-of-study PTX parameters were analyzed with the paired Student t test. Results For patients who underwent PTX, mean cortical bone calcium concentration increased from 220.69 mg/cm³ ± 25.79 to 257.43 mg/cm³ ± 25.46 (t = 8.546, P < .001), whereas medullary bone calcium concentration decreased from 64.75 mg/cm³ ± 15.07 to 61.42 mg/cm³ ± 15.77 (t = 22.293, P < .001) from baseline to follow-up. In patients who did not undergo PTX, mean cortical bone calcium concentration decreased from 296.08 mg/cm³ ± 36.35 to 258.35 mg/cm³ ± 31.46 (t = 7.420, P < .001), but medullary bone calcium concentration increased from 61.13 mg/cm³ ± 13.85 to 62.94 mg/cm³ ± 14.80 (t = 2.370, P = .023) from baseline to follow-up. Conclusion During the course of chronic renal failure, different bone elements involve various pathologic changes. PTX could reverse long-term cortical bone loss reflected in calcium concentration measured with spectral CT; however, it could induce medullary bone loss. ^© RSNA, 2017 Online supplemental material is available for this article.