Efficacy and safety of radiofrequency ablation compared with parathyroidectomy for secondary hyperparathyroidism in dialysis patients: a retrospective single-center study

The patients

This study was approved by the Ethics and Scientific Review Committee of Zhejiang Provincial People’s Hospital. We confirmed that all methods were performed in accordance with relevant guidelines and regulations of prophylaxis declarations, and the retrospective cohort study included all patients diagnosed with SHPT who underwent PTX or ultrasound-guided RFA from June 2014 to December 2020 in our hospital. The inclusion criteria were: (1) 18 to 85 years old; (2) dialytic vintage ≥ 6 months; (3) preoperative concentration of intact PTH (iPTH) > 600 pg/mL; (4) severe PTHS after ineffective medical treatment; (5) at least one hyperplastic parathyroid nodule ≥ 1 cm in diameter found on ultrasound; and (6) follow-up durations ≥ 3 months. Exclusion criteria were: (1) primary or tertiary hyperparathyroidism; (2) severe cardiopulmonary insufficiency and does not tolerate treatment; and (3) history of PTX or RFA.

Intervention

All patients underwent routine high-frequency ultrasound combined with 99mTc-sestamibi SPECT or enhanced CT evaluation for preoperative parathyroid localization. According to the clinical guidelines, combined with the patient’s condition, the clinician judged and fully communicated both methods to the patients. Patients who cannot tolerate general anesthesia or who prefer minimally invasive treatment accept RFA. They were divided into two groups according to the treatment: PTX group and RFA group.

US-guided RFA was performed by the same physician who had extensive experience in US intervention and RFA treatment of parathyroid nodules. After disinfection and local anesthesia, 10-30 ml of sterile water was injected around the parathyroid to establish a layer of thermal insulation to prevent thermal damage to adjacent tissues. Using a US iU22 scanner and high-frequency linear probe (L12-5) (Philips, Netherlands), grayscale imaging was used for guidance, while ultrasound contrast-enhanced (CEUS) with a high-frequency linear probe (L9-3) was used for tracking. The 18G radiofrequency electrode needle (VIVA; STARmed, Goyang, Korea) with a 7 mm active tip was inserted into the target parathyroid nodules to perform thermal ablation. During the procedure, the doctor assessed the patient’s condition and immediately terminated the surgery if hoarseness occurred. During postoperative management, we observed closely whether hematoma or asphyxia occurred. After 4 h, the patients gradually resumed their diet. We systematically assessed whether patients had hoarseness or kicking. If the degree of iPTH decline was unsatisfactory, further investigation was required to determine if there was residual or ectopic parathyroid gland.

Total PTX was administered after general anesthesia and routine disinfection. The patient was placed in the supine position. The anterior transverse neck incision was approximately 5 cm along the dermatoglyphic direction. The skin flaps were separated and fixed below the platysma, and the anterior cervical muscles were separated along the white line of the neck. After complete exposure of the bilateral thyroid and parathyroid glands, the surgeon carefully dissected and protected the bilateral recurrent laryngeal nerves, then completely removed all visible parathyroid glands. Hemostasis was fully achieved and the anterior neck incision was sutured layer by layer. A parathyroid (AT) autotransplantation was performed to cut approximately 30–60 mg of parathyroid tissue into 1 × 1 × 1 mm particles and planted on the brachioradialis forearm.

Clinical data collection

General information on age, gender, dialysis history, clinical symptoms and treatment procedures was collected. Basic clinical laboratory variables, such as serum creatinine (Cr), uric acid (UA), albumin (ALB), hemoglobin (Hb), troponin I (TNI), type natriuretic peptide B (BNP), C-reactive protein (CRP), iPTH, calcium (Ca) and phosphorus (P) levels and indicators related to bone metabolism such as bone-specific alkaline phosphatase (bALP), telopeptides beta C-terminal cross-linked type I collagen (β-CTx), N-terminal osteocalcin (N-MID), N-terminal propeptide of type I total collagen (tP1NP), and 25-hydroxy vitamin D ( 25(OH)D) were collected. Clinical data included number and size of parathyroid nodules, osteoporosis (bone density), carotid arteriosclerosis (carotid artery B-US), hospital stay and postoperative complications.

Monitoring and results

Serum iPTH, calcium and phosphorus concentrations were measured after PTX or RFA at the following time points: 1 month (± 2 weeks), 3 months (± 2 weeks), 6 months (± 1 month), 12 months ( ± 1 month) and 24 months (± 1 month). All patients were followed until death, kidney transplantation, loss, or study termination (June 30, 2021).

The primary endpoint was the proportion of patients in the PTX or RFA group with the target iPTH concentration range during the efficacy phase (endpoint follow-up). According to KDIGO (Kinney Disease Improving Global Outcomes) guidelines21, the target range of iPTH concentration was maintained at approximately 2 to 9 times the upper limit of normal, while achieving targets for iPTH of 124 to 558 pg/mL, calcium of 2.0 to 2.5 mmol/L and phosphorus from 0.97 to 1.62 mmol/L. According to previous studies and guidelines19,21,22, the lowest iPTH level after a successful procedure within 7 days was less than 300 pg/mL. Therefore, our study defined the target range of postoperative iPTH level as less than 300 pg/mL.

Secondary outcomes were differences in changes in iPTH, Ca, and P levels over time between the two groups, long-term prognosis (death or recurrence), and occurrence of postoperative adverse events ( hoarseness, fever, hematoma and hypocalcaemia) . The cumulative response rate was defined as the proportion of patients with iPTH 558 pg/mL. Clinically, serum Ca 5.17. If serum Ca was between 1.8 and 2.1 mmol/L during the perioperative period, oral calcium carbonate (1.8 to 5.4 g/day) and calcitriol (1.0 to 2 .5 μg/day) were administered.

statistical analyzes

All statistical analyzes were performed using SPSS version 26.0 for Mac Sciences version 9.0. Measured data conforming to a normal distribution is displayed as mean ± standard deviation (SD), and other data is displayed as median and interquartile range. Comparisons between parameters were made using the independent sample you essay, Mann–Whitney you test or chi-square test. A linear mixed model was used to compare serum iPTH, Ca, and P concentrations between groups during the efficacy phase. Potential predictors of hypocalcemia were analyzed using logistic regression analysis. Survival analyzes were calculated by Kaplan-Meier survival curves. All results were tested using two-tailed tests and significance was set at P

Ethics statement

This study protocol has been reviewed and approved by the Ethics and Scientific Review Committee of Zhejiang Provincial People’s Hospital, Approval Number [2021QT330]. And the study was exempted from the requirement for written informed consent.

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