US-guided percutaneous radiofrequency ablation of secondary hyperparathyroidism as a bridge to renal transplantation

Abstract

Purpose

Secondary hyperparathyroidism (SHPT) is a frequently encountered problem in patients with end-stage renal disease (ESRD) prior to renal transplantation (RTP), and the successful management of SPHP currently is challenging. In this study, we aimed to investigate the effectiveness of radiofrequency ablation (RFA) for SHPT as a bridge to RTP and to evaluate post-transplantation outcomes.

Methods

Patients with SHPT receiving RFA treatment were retrospectively reviewed, and those underwent RTP after ablation were enrolled. Serum parathyroid hormone (PTH), calcium, and phosphate levels were collected before ablation and at follow-up periods. The primary endpoints are PTH values at time of transplantation and at the final follow-up. The secondary endpoints were RFA-related complications, serum calcium and phosphate concentrations, and allograft function.

Results

Eleven patients with 43 enlarged parathyroid glands were treated with 16 RFA sessions and enrolled in the study. Complete ablation was achieved in all glands with transient hoarseness and hypocalcemia occurring in two and five of the treatments, respectively. At time of transplantation, serum PTH levels (246.7 ± 182.6 pg/mL) were significantly lower than that before RFA (1666.55 ± 874.48 pg/mL, p < 0.001) and were all within guideline-oriented range. The median follow-up period was 57.2 months. At last visit, all patients were alive, with normal PTH values and functioning grafts.

Conclusions

Ultrasound-guided RFA is effective for destroying hyperplastic parathyroid tissues in SHPT patients, whose PTH values fall within the guideline-oriented range both pre-and post-transplantation. Percutaneous RFA acts as an effective bridge to RTP and might provide a new management paradigm designed to improve post-transplant outcomes.

Keywords:

• Hyperparathyroidism
• radiofrequency ablation
• thermal ablation
• renal transplantation
• parathyroid hormone

Introduction

Chronic kidney disease (CKD) has emerged as a leading cause of mortality worldwide in the twenty-first century [1]. Renal transplantation (RTP) is currently the best therapeutic option for patients with end-stage renal disease (ESRD), as it can improve patient survival while increasing the quality of life [2]. In the past decade, the number of RTP has rapidly increased. As of February 2021, approximately 91,000 awaited RTP in the United States, and over 3000 new cases have been added to the transplant waiting lists monthly [3]. Although renal transplant recipients can benefit from improved allograft survival, they can be burdened with secondary hyperparathyroidism (SHPT) before and even after transplantation [4,5].

SHPT is a frequently encountered condition in ESRD [6] and is strongly correlated with chronic allograft nephropathy, cardiovascular morbidity, and mortality after RTP [7–9]. Therefore, the Kidney Disease Improving Global Outcomes (KDIGO) guidelines have suggested serum parathyroid hormone (PTH) concentration targets in hyperparathyroid candidates eligible for RTP [10]. Currently, parathyroidectomy (PTX) is a well-established treatment method for patients with SHPT who fail to respond to pharmacological therapy to normalize both calcium and PTH levels [11–13]. Nevertheless, guidelines on the optimal type of surgical parathyroid management are not specifically defined [12], and it is sometimes difficult to determine the precise amount of the gland to be removed. Some surgeons prefer subtotal PTX because it has a lower risk of complications, such as hypoparathyroidism and (persistent) hypocalcaemia [14], whereas others prefer total PTX plus autotransplantation, which might have a lower recurrence rate and a less invasive reoperation. Proper management of SHPT prior to transplantation is critical to minimize the number of complications and to avoid hypoparathyroidism and the risk of unsatisfactory PTH reduction.

Notably, the renal allograft is able to maintain adequate levels of serum calcium and phosphate, and thus, these parathyroid glands should no longer be stimulated to synthesize and secrete PTH excessively [5]. Indeed, in 57% of kidney transplant recipients, serum PTH levels can resolve spontaneously within two years post-transplantation [5]. Hence, for patients who are likely to receive RTP in the future, a less aggressive operative approach to parathyroid operations for SHPT may be sufficient or even beneficial. Therefore, significant attention has been devoted to minimally invasive therapies.

Indeed, several US-guided ablation modalities such as ethanol injection [15,16], microwave ablation [17] and high-intensity focused ultrasound (US) [18] have been widely investigated as nonsurgical treatment methods for SHPT. In the past 10 years, we have been committed to managing SHPT with radiofrequency ablation (RFA), and its safety and efficacy profiles have been well-established [19,20]. However, the potential beneficial role of RFA while awaiting RTP remains unclear. As the limited supply of donor organs significantly prolongs the waiting time for transplantation, RFA can represent a valuable option for efficient definitive treatment or may bridge the time from overt severe SHPT until RTP may be performed. Based on these assumptions, we conducted the present study, in which RFA was given as the only treatment for SHPT in ESRD patients, to assess the efficacy of RFA as a bridge to RTP. We also sought to compare the clinical outcomes of RFA with previously reported PTX data to help clinicians in their decision-making regarding the management of this challenging disease.

Methods

Study design

This study was a retrospective analysis of a prospective database, and we aimed to assess the effect of RFA on SHPT in patients with ESRD before and after RTP. The diagnostic criteria for SHPT associated with ESRD were based on an estimated glomerular filtration rate (eGFR) <15 mL/min/1.73 [21] m² and serum intact PTH levels >300 pg/mL [22] on at least two sequential measurements. The primary endpoints of this study were serum intact PTH levels at the time of transplantation and the last post-transplantation follow-up. The secondary endpoints were RFA complications, serum calcium and phosphate concentrations, and allograft function.

Patient population

This study was approved by the Human Ethics Committee of our institute (No. 20130115). The requirement to obtain informed consent was waived because of the retrospective nature of this study. Written informed consent was obtained from all patients before RFA treatment. All the enrolled patients fulfilled the following criteria: (a) patients with SHPT associated with ESRD; (b) patients underwent RFA treatment for enlarged parathyroid glands; (c) patients receiving RTP after RFA treatment. Exclusion criteria included patients underwent a surgical treatment for SHPT before or after ablation. Further, patients with incomplete follow-up data were also excluded.

Percutaneous radiofrequency ablation procedure

All RFA procedures of the enrolled centers were performed by the same radiologist with 24 years of experience in interventional US and 12 years of experience in the RFA treatment of thyroid and hyperplastic parathyroid nodules. An RFA system consisting of a radiofrequency generator (VIVA; STARmed, Goyang, Korea) and an 18-gauge monopolar internally cooled electrode (7-cm in length with a 0.7-cm active tip; VIVA; STARmed) was used in this study. Real-time US scanning was performed using Philips IU22 (Philips, Netherlands) or GE Logiq E9 (GE Healthcare, USA) with a high-frequency linear transducer (L12-5/ML6-15).

The patient was placed in a supine position with the neck extended. Before RFA, the US characteristics (i.e., maximum diameter, position, echo features, and contrast material enhancement) of the affected parathyroid glands were carefully evaluated (Figure 1(a,b)) by the operator, and the best puncture site was located. After routine disinfection of the neck, local anesthesia with 2% lidocaine was administered. Then, lidocaine in normal saline solution (1:1) was injected surrounding the hyperplastic gland capsule to protect the critical structures (i.e., recurrent laryngeal, vagal nerves, and vascular) from thermal injury (Figure 1(c)). The electrode was percutaneously inserted into the targeted parathyroid gland and positioned at the back of the gland, with its tip 1 mm away from the distal capsule. As preserving some intact glands during the ablation process to ensure moderate PTH secretion is an important issue, the 1-mm preservation ablation method was used to keep some parathyroid tissues intact to maintain the secretion of PTH. Ablation was initiated with real-time grayscale US images (Figure 1(d)). A moving-shot technique with the fluid spacing method was used for RFA treatment, and according to previous studies, ablation power was mainly set at 35 W. Treatment was terminated when the transient hyperechoic zone covered the whole gland. Subsequently, contrast-enhanced and color doppler US (Figure 1(e)) was used to further evaluate the extent of ablation. If the non-enhanced zone covers the entire ablated gland (Figure 1(f)), the treatment was considered complete. Otherwise, an additional ablation was performed immediately.

Figure 1. Ultrasound image of hyperplastic parathyroid gland before and after radiofrequency ablation (RFA). (a) Color doppler ultrasound (US) examination reveals a solid nodule (arrow) presence of abundent flow signals before RFA; (b) The hyperplastic parathyroid gland presents hyperenhancement (arrow) in the arterial phase at preablation contrast-enhanced US examination; (c) Hydrodissection technique (arrow) is applied in the RFA procedure to protect the critical structures from thermal injury; (d) After starting ablation, hyperechoic zone (arrow) was observed surrounding radiofrequency electrode; At the end of ablation, (e) no obvious blood flow signal (arrow) displays intra-gland, and (f) non-enhanced zone (arrow) covers the whole ablated gland on US imaging.

After complete ablation on one side, RFA treatment will be continued on the other side. However, if the patient experienced dysphonia after the ablation procedure on one side, the ablation was terminated and laryngoscopy was performed to identify whether recurrent laryngeal nerve injury had occurred. Based on the results of laryngoscopy, we will determine whether contralateral ablation should be performed. At the end of ablation, mild neck compression was applied to the side of treatment for 20-30 min and the patients remained under close observation for two hours.

Clinical data collection and follow-up

All demographic data, including sex, age, cause of ESRD, dialysis history, and dialysis type of the patients, were recorded. Levels of intact PTH, serum calcium, phosphorus, alkaline phosphatase (ALP), and creatinine were measured 24 h before ablation. Renal transplant data included the donor type, graft survival, and overall survival. In addition, serum intact PTH, calcium, and phosphate levels were collected at the time of transplantation and at the last post-transplantation follow-up. Major and minor complications were defined according to the Society of Interventional Radiology criteria. A major complication was an event that led to substantial morbidity and disability, increased the level of care, resulted in hospital admission, or substantially lengthened hospital stay. All other complications were considered to be minor. Hypocalcemia was indicated as a serum calcium level below 2.0 mmol/L (normal range 2.11–2.52 mmol/L), and it was further classified as mild–moderate hypocalcemia (total serum calcium 1.8–2.0 mmol/L) and serious hypocalcemia (total serum calcium <1.8 mmol/L) [17,20]. Intravenous calcium supplementation was initiated in patients with serious hypocalcemia or symptoms of hypocalcemia. Patients with mild-to-moderate hypocalcemia were administered oral calcium supplements.

Statistical analysis

Continuous outcomes were presented as mean ± standard deviation and were analyzed using paired-sample t-tests or Wilcoxon signed-rank tests, as applicable. Categorical variables are reported as percentages. Statistical analyses were performed using the SPSS software (version 18.0). Significant differences were defined as p-values of less than 0.05.

Results

Patient demographics and clinical characteristics

From May 2013 to March 2022, 167 consecutive patients with ESRD were treated with RFA for SHPT at our three centers. Among them, 14 underwent primary RTP after RFA (Figure 2). Three patients were excluded from this study because of operation history before ablation (n = 1) or incomplete follow-up data (n = 2). And eleven patients were enrolled in the final analysis. The demographic and baseline clinical characteristics of these patients are summarized in Table 1, which included three men and eight women, mean age of 45.4 years (range, 32–60 years). Of the patients, three had been undergoing hemodialysis for 89 ± 37 months, while eight had been undergoing peritoneal dialysis for 51 ± 23 months. The causes of ESRD were chronic nephritis (n = 9), hypertension (n = 1) and IgA nephropathy (n = 1). All the patients had high serum intact PTH levels (1666.55 ± 874.48 pg/mL; normal value, 15–65 ng/L) before RFA. The serum phosphorus and calcium levers of these patients were 2.49 ± 0.55 (normal value, 0.85–1.51 mmol/L) and 2.53 ± 0.19 mmol/L (normal value, 2.11–2.52 mmol/L), respectively. The mean follow-up duration of the patients after RFA treatment was 57.2 months (range 23–99 months). Among these patients, five were followed up for at least 5 years, and eight cases were followed up for at least 3 years.

Figure 2. Flowchart summarizes patient inclusion. ESRD: end-stage renal disease; RFA: radiofrequency ablation.

Table 1. Baseline characteristics of ESRD-patients with secondary hyperparathyroidism who underwent radiofrequency ablation before kidney transplantation.

Patient characteristics	Value
Sex, N (%)
Male	3
Female	8
Age (years)	45.4 ± 7.7 (32–60)
ESRD cause
Chronic nephritis	9
hypertension	1
IgA nephropathy	1
Dialysis modality
Hemodialysis	3
Peritoneal dialysis	8
Duration of dialysis (months)	61.1 ± 31.2 (24–131)
Presenting symptoms, N (%)
Bone pain	3
Skin itching	4
Laboratory data pre-RFA treatment
Serum intact PTH (pg/mL)	1666.55 ± 874.48 (713.2–3620)
Serum calcium(mg/dL)	2.53 ± 0.19 (2.17–2.71)
Serum phosphorus(mg/dL)	2.49 ± 0.55 (1.80–3.34)
Serum Alk-ptase (U/L)	191.55 ± 111.18 (98–426)
Serum creatinine (µmol/L)	1190.31 ± 352.55 (642–1793)
No. parathyroid glands
3	1
4	10
Maximum diameter of gland (cm)	1.5 ± 0.7 (0.5–3.8)
Period from radiofrequency ablation to transplantation	22.1 ± 21.5 (2.5–79)
Type of transplant
Live donor	2
Deceased donor	9
Follow-up period after RFA (months)	57.2 ± 28.9 (23–99)
Follow-up period after kidney transplantation (months)	35.1 ± 25.7 (9–76)

Note. Unless otherwise indicated, data are mean ± standard deviation, with the range in parentheses. ESRD: end-stage renal disease; RFA: radiofrequency ablation; PTH: parathyroid hormone.

Technical outcomes after RFA

Forty-three enlarged parathyroid glands from 11 RTP candidates were treated with RFA. The number of glands that had been removed from each patient was 3.9. One patient had three hyperplastic parathyroid glands, and the other ten had four glands. The mean maximal diameter of these glands was 1.5 cm (range 0.5–3.8 cm). A total of 16 RFA sessions were performed for these patients, including a single-session treatment in 6 patients and a planned double-session treatment in 5 patients. All 43 glands showed hyperenhancement in the arterial phase and were isoechoic in the late phase at pre-ablation contrast-enhanced US examination, and this enhancement mode was consistent with high parathyroid function [17]. After RFA, all glands showed non-enhancement, indicating that complete ablation was achieved.

Laboratory analysis and post-transplantation outcome based on normalization of PTH

The treatment results for the RTP candidates are summarized in Table 2. Before RFA, the mean value of serum intact PTH in the 11 patients was 1666.6 ± 874.5 pg/mL (range 1849–3620 pg/mL), which significantly decreased to 92.7 ± 85.4 pg/mL (range 3–274 pg/mL) 1 day after RFA, 177.1 ± 150.1 pg/mL (range: 26.1–473 pg/mL) 1 month after RFA, 246.7 ± 182.6 pg/mL (range: 34.2–560 pg/mL) at the time of transplantation, and 53.1 ± 7.5 pg/mL (range: 40.3–62 pg/mL) at the end of follow-up (Figure 3, all p < 0.001). And all the patients demonstrated PTH values in the range recommended by the Kidney Disease Improving Global Outcomes (KDIGO) CKD-MBD Work Group guidelines (600 pg/mL) prior to transplantation, and after transplantation, all the patients had intact PTH values in the normal range (less than 65 pg/mL) at the end of post-transplantation follow-up. Similar results were achieved for serum calcium levels, which were 2.53 ± 0.19 mmol/L before RFA, 2.10 ± 0.33 mmol/L 1 day after RFA and 2.30 ± 0.14 mmol/L at the end of follow-up.

Figure 3. Changes in intact parathyroid hormone (PTH) values before and after radiofrequency ablation. All p values were obtained with paired t-tests. Fine dotted lines present target PTH range recommended by current Kidney Disease Improving Global Outcomes guideline pre- and post-transplantation.

Table 2. Outcomes of radiofrequency ablation for patients with secondary hyperparathyroidism at follow-up period.

Laboratory test	Intact PTH (pg/mL)	Calcium (mmol/L)	Phosphorus (mmol/L)
Before RFA	1666.55 ± 874.48	2.53 ± 0.19	2.49 ± 0.55
After RFA (1-day)	92.75 ± 85.47	2.10 ± 0.34	1.66 ± 0.45
After RFA (1-month)	177.15 ± 150.14	2.21 ± 0.23	1.24 ± 0.51
At time of transplantation	246.65 ± 182.61	2.29 ± 0.20	1.37 ± 0.41
At last post-transplantation follow-up	53.14 ± 7.53	2.30 ± 0.14	1.20 ± 0.30

Note. Data are mean ± standard deviation; RFA: radiofrequency ablation; PTH: parathyroid hormone.

We then evaluated the effect of normalization of serum intact PTH levels before and after RTP on the overall graft and patient survival. The serum creatinine level at the last visit was 108.2 ± 16.3 µmol/L (normal value, 45–84 µmol/L). Graft loss was defined as retransplantation, dialysis resumption, or patient death with or without a functional allograft. Notably, during the post-transplantation follow-up of 35.1 ± 25.7 months, no patient developed graft failure after transplantation.

Complications related with RFA

All patients with ESRD tolerated the ablation procedure well. Hoarseness occurred in two of the treatments and all recovering within three months spontaneously. Four patients presented with mild to moderate hypocalcemia after treatment, which slowly disappeared with oral calcium supplements during the subsequent period. Serious hypocalcemia occurred in one patient requiring intravenous calcium supplementation. No serious adverse events such as local infection, skin burning, or damage to the vital structures of the neck were observed. No mortality was directly associated with RFA treatment. The median interval from RFA to RTP was 22 months (range 2.5–79 months), and none of the patients was excluded from transplant operation because of PTH values while on the waiting list following RFA treatment.

Discussion

The survival advantages of RTP over long-term dialysis have been generally well described [23], and accompanied by an increasing number of patients on the RTP waiting list. The treatment strategy for SHPT related to ESRD might have to shift toward a less aggressive approach in a carefully selected group of patients, ensuring adequate parathyroid function both before and after RTP. The present study reported on a limited number of patients with ESRD awaiting RTP treated with RFA as an efficient, minimally invasive strategy for the management of SHPT. Our results provide evidence that US-guided RFA could effectively reduce the levels of serum intact PTH, calcium, and phosphorus in patients with ESRD and SHPT with acceptable additional complications. This determination acts as an effective bridge to RTP and could provide a new management paradigm designed to improve post-transplant outcomes.

Evidence indicates that both persistent hyperparathyroidism and hypoparathyroidism are associated with decreased renal graft function and worse graft survival [3,11,12,24]. Therefore, serum intact PTH should be maintained within adequate levels pre- and post-transplantation to achieve good graft outcomes. Unfortunately, the clinical management of SHPT is currently controversial and limited. Cinacalcet, a calcimimetic agent, plays a prominent role in the treatment of patients with SHPT on dialysis, as stated in the KDIGO guidelines [6]. However, some reports indicate that the use of cinacalcet during RTP can exacerbate renal injury and contribute to delayed graft function following transplantation [4,25]. Also, the use of calcimimetics pre-RTP was reported to be associated with 30% of mild hypercalcemia after RTP, and it is potentially related with recurrent SHPT and the nephrocal-cinosis developing months after RTP [26]. Therefore, it has not been approved for use in RTP recipients.

PTX is a guideline-oriented therapeutic strategy for hyperparathyroidism in a pre-transplant setting. The relevant references were carefully reviewed, and the detailed results are presented in Table 3 [11,24,27–33]. The advantages of parathyroidectomy before RTP have been well-described in these studies with regard to PTH levels, graft function, and bone mineral density after transplantation. Many transplant centers recommend parathyroidectomy for patients who are in the pre-transplantation setting if they exhibit at least a moderate form of SHPT [34]. However, the rate of persistent hyperparathyroidism post-transplantation ranges from 0 to 36%, as presented in the above studies [24,27,29,30]. In contrast, our results present that all patients had PTH values in the range recommended by the KDIGO CKD-MBD Work Group guidelines at the time of transplantation, and PTH values were maintained at normal levels (less than 65 pg/mL) during the post-transplantation period, which is somewhat superior to PTX. Several reasons could explain the better outcomes of RFA in our study. The first was the accurate and comprehensive location of the parathyroid mass. We combined Tc-MIBI scanning and US to localize the parathyroid mass. Previous studies reported that the sensitivity of Tc-MIBI scanning was 84% and that of US was 72.5% [35], while a combination of MIBI scanning and US could increase the sensitivity to 92.9–100% [36]. Targeted fine-needle aspiration cytology and evaluation of PTH in the aspirate were also used to confirm the diagnosis of hyperplastic parathyroid lesions in US-accessible locations. Using these techniques, four glands were detected in 90.9% (10/11) of the patients and were all ablated, as suggested in our previous study [19]. All RFA procedures were performed by radiologist with > 10 years of thyroid ablation experience, ensuring full elimination of nodules with low occurrence of complications. Thus, it is difficult to predict the extent to which different manipulation procedures applied to perform ablations in different groups can affect treatment outcomes.

Table 3. Results of managing secondary hyperparathyroidism before renal transplantation using parathyroidectomy compared with our findings with radiofrequency ablation.

NO	Study/year of publication	Study design	No. of patients	Procedure	Mean follow-up Time (months)	Graft function criteria	Persisting hyperparathyroidism post-transplantation	Conclusion
1	Current study	Retrospective	11	Radiofrequency ablation	57	Serum creatinine	0	Radifrequency ablation can be an attractive bridging strategy for the management secondary hyperparathyroidism in patients eligible for kidney transplantation
2	Oruc, A et al. 2021 [24]	Retrospective	12	Parathyroidectomy	44	eGFR, Serum creatinine	8.30%	Parathyroidectomy before transplant is advantageous with better graft function
3	Mathur et al. 2021 [21]	Retrospective	205	Parathyroidectomy	36	NS	14.10%	Parathyroidectomy should be considered as treatment for secondary hyperparathyroidism, especially in kidney transplantation candidates on maintenance dialysis for ≥3 years
4	Okada et al. 2020 [25]	Retrospective	55	Total parathyroidectomy with a forearm autograft + thymic tongue	69	eGFR	NS	Pre-kidney transplantation parathyroidectomy should be considered to prevent persistent hypocalcemia and deterioration of the renal graft function
5	Koh et al. 2020 [26]	Retrospective	46	Total parathyroidectomy/Subtotal parathyroidectomy	120	Serum creatinine	2.20%	Parathyroidectomy resulted in lower parathyroid hormone levels after kidney transplantation in comparison to patients who received calcimimetics.
6	van der Plas et al. 2019 [27]	Retrospective	102	Total Parathyroidectomy/Subtotal Parathyroidectomy	60	eGFR	3.70%	Timing of parathyroidectomy before or after kidney transplantation does not independently impact graft function over time
7	Littbarski et al. 2018 [28]	Retrospective	67	Parathyroidectomy	84	eGFR, Serum creatinine	NS	Parathyroidectomy should be conducted before transplantation or, if this is not possible, preferably after the first post-transplant year
8	Callender et al. 2017 [11]	Retrospective	57	Subtotal parathyroidectomy/Total parathyroidectomy with autotransplantation	12	eGFR	NS	Pre-kidney transplantation parathyroidectomy decreases post–kidney transplantation graft failure
9	Jeon et al. 2012 [29]	Retrospective	37	Subtotal parathyroidectomy/Total parathyroidectomy with or without autotransplantation	64	eGFR	36%	Pretransplant parathyroidectomy should be considered for patients with severe hyperparathyroidism
10	Chou et al. 2008 [30]	Retrospective	7	Total parathyroidectomy plus autotransplantation	48.7	Serum creatinine	0	Parathyroidectomy followed by kidney transplantation performed for symptomatic secondary hyperparathyroidism can improve the bone mineral density

Note. eGFR: estimated glomerular filtration rate.

Although other factors such as donor and recipient sex and age, cold ischemia time, history of diabetes, and donor type can determine the post-transplant eGFR course, normalization of PTH levels should have contributed to good graft function in this study. Based on our results, for patients with ESRD-related hyperparathyroidism and listed for transplantation, a minimally invasive strategy, RFA, for instance, seems to be sufficient, at least regarding satisfactory PTH values, low major complication rate, and positive effect on graft function.

This study has several limitations. First, this study was conducted as a retrospective design with all its inherent limits, including the presence of some unavoidable selection biases. Well-designed prospective studied are needed to further confirm these findings. Second, the same sample size of 11 cannot be able to provide high enough level of evidence to lead to changes in clinical care. Also, further research is required to confirm the potentially beneficial effects of RFA on biochemical values, quality of life, and treatment satisfaction in patients with SHPT in a larger sample size. Third, we failed to compare treatment outcomes of RFA cases with those of PTX in randomized controlled patterns. Thus, it lacks adequate power to identify the superiority of RFA in SHPT management. Despite all of the above limitations, this study is the first to explore the possibility of a patient-tailored, less aggressive approach as a treatment strategy for SHPT patients expecting RTP in the near future.

In summary, our experience provides evidence that US-guided RFA may be a robust bridging therapy for SHPT in candidates for RTP. Interventional radiologists should be aware of the high prevalence of ectopic glands, and combined MIBI scanning and US to localize the gland together with aspirate PTH evaluation should help guide the ablation procedure to achieve good clinical outcomes. Hypocalcemia is common in the immediate post-abtion period, and close monitoring is critical. However, we also highlight several outstanding questions that remain on this topic. We suggest that medical societies involved in the transplantation care spectrum should convene experts from multiple disciplines to collaboratively manage hyperparathyroidism in transplantation candidates, as well as areas where clinical evidence is lacking and further research is needed.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data can be availability from the corresponding author upon reasonable request.

Additional information

Funding

This work was supported in part by the National Natural Science Foundation of China [Grants 82171943, 82272005], Shanghai Rising-Star Program [21QA1407200], and Special Project for Clinical Research of Health Industry of Shanghai Health Commission [20214Y0151].