Resurgence of parathyroidectomy: evidence and outcomes

Treatment of Secondary Hyperparathyroidism and Posttransplant Tertiary Hyperparathyroidism

INTRODUCTION

Secondary hyperparathyroidism (sHPT) is prevalent in dialysis patients and can lead to tertiary hyperparathyroidism (tHPT) after kidney transplantation. We aimed to assess the association of pretransplant sHPT treatment on posttransplant outcomes.

METHODS

We reviewed kidney transplant patients treated with parathyroidectomy or cinacalcet for sHPT. We compared patients biochemical and clinical parameters, and outcomes based on sHPT treatment.

RESULTS

A total of 41 patients were included: 18 patients underwent parathyroidectomy and 23 patients received cinacalcet prior to transplantation. There were no significant differences between demographics, comorbidities, allograft characteristics or pre-sHPT intervention parathyroid hormone (PTH) and calcium levels. Patients that underwent parathyroidectomy were on dialysis for longer, although not significantly (71.9 versus 42.3 mo, P = 0.051). At time of transplantation, patients treated by parathyroidectomy had increased rates of controlled sHPT (88.9%; 16/18 versus 47.8%; 11/23, P = 0.008). Patients treated by parathyroidectomy had decreased development of tHPT (5.9%; 1/17; versus 42.1%; 8/19, P = 0.020) as well as decreased rates of posttransplant treatment with cinacalcet (11.1%; 2/18 versus 52.2%; 12/23, P = 0.008). Three patients treated with cinacalcet underwent parathyroidectomy after transplantation. Median PTH after transplant remained lower in patients treated by parathyroidectomy prior to transplant compared to those treated with cinacalcet (60.7 [interquartile range 39.7-133.4] versus 170.0 [interquartile range 128.4-292.7], P = 0.001). Allograft function and survival were similar for parathyroidectomy and cinacalcet, with median follow-up after transplantation of 56.7 and 34.2 mo, respectively.

CONCLUSIONS

sHPT treated by parathyroidectomy is associated with controlled PTH levels at transplantation and decreased rates of tHPT. Long-term outcomes should be studied on a larger scale.

Roles of PTH and FGF23 in kidney failure: a focus on nonclassical effects

Parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) each play a central role in the pathogenesis of chronic kidney disease-mineral and bone disorder (CKD-MBD). Both hormones increase as kidney function declines, presumably as a response to maintain normal phosphate balance, but when patients reach kidney failure, PTH and FGF23 fail to exert their phosphaturic effects, leading to hyperphosphatemia and further elevations in PTH and FGF23. In patients with kidney failure, the major target organ for PTH is the bone, but elevated PTH is also associated with mortality presumably through skeletal and nonskeletal mechanisms. Indeed, accumulated evidence suggests improved survival with PTH-lowering therapies, and a more recent study comparing parathyroidectomy and calcimimetic treatment further suggests a notion of "the lower, the better" for PTH control. Emerging data suggest that the link between SHPT and mortality could in part be explained by the action of PTH to induce adipose tissue browning and wasting. In the absence of a functioning kidney, the classical target organ for FGF23 is the parathyroid gland, but FGF23 loses its hormonal effect to suppress PTH secretion owing to the depressed expression of parathyroid Klotho. In this setting, experimental data suggest that FGF23 exerts adverse nontarget effects, but it remains to be confirmed whether FGF23 directly contributes to multiple organ injury in patients with kidney failure and whether targeting FGF23 can improve patient outcomes. Further efforts should be made to determine whether intensive control of SHPT improves clinical outcomes and whether nephrologists should aim at controlling FGF23 levels just as with PTH levels.

RNA-Seq-based transcriptomics analysis during the photodynamic therapy of primary cells in secondary hyperparathyroidism

BACKGROUND

The aim of this study was to identify changes in gene expression before and after 5-aminolevulinic acid-mediated photodynamic therapy (5-ALA-PDT) and to investigate the potential mechanism of 5-ALA-PDT based on ribonucleic acid sequencing (RNA-Seq) analysis.

METHODS

Secondary hyperparathyroidism (SHPT) primary cells were isolated from surgically excised specimens and exposed to laser light. The transcription profiles of SHPT primary cells were identified through RNA-Seq. Differentially expressed genes (DEGs) were identified. Enrichment of functions and signaling pathway analysis were performed based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Quantitative real-time polymerase chain reaction (RT-qPCR) and western blot analysis were used to validate genes based on RNA-Seq results.

RESULTS

In total, 1320 DEGs were identified, of which 1019 genes were upregulated and 301 genes were downregulated. GO and KEGG pathway analyses identified significantly enriched pathways in DEGs, including TGF beta in extracellular matrix (ECM), negative regulation of triglyceride biosynthetic process, protein heterodimerization activity, systemic lupus erythematosus, ECM-receptor interaction, focal adhesion and protein digestion and absorption. Protein-protein interaction (PPI) network analyses identified potential heat shock protein (HSP) interactions among the DEGs. Eight HSP genes were also identified that were most likely involved in 5-ALA-PDT, which were further validated by RT-qPCR and western blotting.

CONCLUSIONS

The findings of this descriptive study reveal changes in the transcriptome profile during 5-ALA-PDT, suggesting that gene expression and mutation, signaling pathways, and the molecular network are altered in SHPT primary cells. The above findings provide new insight for further studies on the mechanisms underlying 5-ALA-PDT in SHPT.

Parathyroidectomy vs Cinacalcet Among Patients Undergoing Hemodialysis

CONTEXT

Parathyroidectomy (PTx) and cinacalcet are both effective treatments for secondary hyperparathyroidism in hemodialysis patients, but limited data exist comparing the long-term outcomes of these interventions.

OBJECTIVE

We aimed to compare the risk of mortality among hemodialysis patients who underwent PTx and those who started treatment with cinacalcet.

METHODS

In this prospective cohort study, comprising patients from the Japanese Society for Dialysis Therapy Renal Data Registry, patients who had intact parathyroid hormone (PTH) levels ≥ 300 pg/mL in late 2007 and underwent PTx or started treatment with cinacalcet in 2008 to 2009 were matched by propensity score at 1:3. PTx and cinacalcet were compared for all-cause mortality within 6 years.

RESULTS

Among eligible patients, 894 patients who underwent PTx were matched with 2682 patients who started treatment with cinacalcet. The median baseline intact PTH levels were 588 pg/mL and 566 pg/mL in the PTx and cinacalcet groups, respectively. PTx resulted in greater reductions in intact PTH, calcium, and phosphorus levels compared with cinacalcet. During the 6-year follow-up period, 201 patients (22.5%) in the PTx group and 736 patients (27.4%) in the cinacalcet group died. PTx was associated with a lower risk of mortality compared with cinacalcet (hazard ratio, 0.78 [95% CI, 0.67-0.91]; P = 0.002). This association was more pronounced in patients with intact PTH levels ≥ 500 pg/mL and in patients with serum calcium levels ≥ 10.0 mg/dL (both P for interaction < 0.001).

CONCLUSION

PTx compared with cinacalcet is associated with a lower risk of mortality, particularly among patients with severe secondary hyperparathyroidism.

A retrospective observational study of patients on maintenance hemodialysis receiving parathyroidectomy by ultrasonic scalpel

Background

Secondary hyperparathyroidism (SHPT) remains a common complication in many patients on maintenance hemodialysis. Kidney Disease Improve Global Outcomes (KDIGO) 2017 guidelines suggest that parathyroidectomy (PTX) should be performed in severe SHPT patients with chronic kidney disease stage 3a-stage 5D. In the present study, we observed the efficacy of ultrasonic scalpel for PTX in SHPT patients on maintenance hemodialysis.

Methods

A total of 74 patients on maintenance hemodialysis who underwent PTX (34 with traditional electrocautery and 40 with an ultrasonic scalpel) were observed between August 2020 and August 2021 at Xiangyang Central Hospital (Hubei University of Arts and Science). Baseline demographic and clinic characteristics were collected pre- and post-PTX. Moreover, the postoperative complications and operation time were assessed between the two groups.

Results

The univariate analysis showed that there was no statistical significance in weight, dialysis duration, serum potassium, serum calcium, serum magnesium, alkaline phosphate, triglyceride, and intact parathyroid hormone (iPTH) before and after PTX between the two groups (P > 0.05). The operation time in the ultrasonic scalpel group was significantly decreased compared with the traditional electrocautery group (P < 0.05). Compared with the traditional electrocautery group, the drainage amount was significantly reduced in the ultrasonic scalpel group, and the number of days with drain and postoperative hospital stay were also remarkably decreased (P < 0.05).

Conclusions

The use of ultrasonic scalpel significantly reduced the operation time and postoperative hospital stay in patients on maintenance hemodialysis undergoing PTX.

Differentiating the causes of adynamic bone in advanced chronic kidney disease informs osteoporosis treatment

Patients with chronic kidney disease (CKD) have an increased fracture risk because of impaired bone quality and quantity. Low bone mineral density predicts fracture risk in all CKD stages, including advanced CKD (CKD G4-5D). Pharmacological therapy improves bone mineral density and reduces fracture risk in moderate CKD. Its efficacy in advanced CKD remains to be determined, although pilot studies suggest a positive effect on bone mineral density. Currently, antiresorptive agents are the most commonly prescribed drugs for the prevention and therapy of osteoporosis. Their use in advanced CKD has been limited by the lack of large clinical trials and fear of causing kidney dysfunction and adynamic bone disease. In recent decades, adynamic bone disease has evolved as the most predominant form of renal osteodystrophy, commonly associated with poor outcomes, including premature mortality and progression of vascular calcification. Evolving evidence indicates that reduction of bone turnover by parathyroidectomy or pharmacological therapies, such as calcimimetics and antiresorptive agents, are not associated with premature mortality or accelerated vascular calcification in CKD. In contrast, chronic inflammation, oxidative stress, malnutrition, and diabetes can induce low bone turnover and associate with poor prognosis. Thus, the conditions causing suppression of bone turnover rather than the low bone turnover per se may account for the perceived association with outcomes. Anabolic treatment, in contrast, has been suggested to improve turnover and bone mass in patients with advanced CKD and low bone turnover; however, uncertainty about safety even exceeds that of antiresorptive agents. Here, we critically review the pathophysiological concept of adynamic bone disease and discuss the effect of low bone turnover on the safety and efficacy of anti-osteoporosis pharmacotherapy in advanced CKD.

Old and New Drugs for the Management of Bone Disorders in CKD

Disturbances in mineral and bone metabolism are common in patients with chronic kidney disease (CKD), especially those undergoing dialysis. Renal osteodystrophy, which describes an alteration of bone morphology, is an important component of this systemic disorder and may explain the elevated risk of fracture which adversely affects morbidity and mortality. The most common form of renal osteodystrophy is high-turnover bone disease (osteitis fibrosa), which is induced by secondary hyperparathyroidism (SHPT). During the past decade, there has been considerable advances in the management of SHPT, with the introduction of the calcimimetic agents, the optimized use of nutritional and active vitamin D, and the accumulated experience with surgical parathyroidectomy. Studies supported that these advances could translate into improvement of renal bone disease and fracture prevention, as well as decreasing the risk of cardiovascular events and mortality. In this review, we summarize the available clinical evidence on the effect of old and new drugs on bone disorders in patients with CKD.

Surgery for Renal Hyperparathyroidism in the Era of Cinacalcet: A Single-Center Experience

BACKGROUND AND AIMS

There are only few data on the influence of cinacalcet on the outcome of parathyroidectomy in patients with renal hyperparathyroidism. Indication and timing of surgery have changed since its introduction, especially with regard to kidney transplantation. Therefore, we retrospectively analyzed patients undergoing parathyroidectomy for renal hyperparathyroidism in our institution.

MATERIAL AND METHODS

Between 2008 and 2015, 196 consecutive operations in 191 patients were analyzed. About 80 operations (41%) were performed in patients receiving cinacalcet compared with 116 operations (59%) in patients without cinacalcet. Clinical data, preoperative medication, pre- and postoperative laboratory values, type and details of surgery including complications, as well as cardiovascular complications and kidney transplantation with graft function were recorded.

RESULTS

Demographical data were similar in patients with or without cinacalcet treatment. A total of 54% of patients received a kidney graft before or after parathyroidectomy. Pre- and postoperative parathormone levels were similar in both groups (preoperatively 755 vs 742 ng/L, postoperatively 50 vs 46 ng/L, p > 0.10), whereas patients with cinacalcet showed significantly lower calcium levels preoperatively (2.28 vs 2.41 mmol/L, p = 0.0002). There was no difference in recurrence or persistence of hyperparathyroidism, duration of surgery, hospital stay, or complication rate. Creatinine levels in patients with tertiary hyperparathyroidism were similar after 1-year follow-up.

CONCLUSION

Cinacalcet did not influence outcome of patients with parathyroidectomy for renal hyperparathyroidism and can be safely offered to patients not responding to medical treatment.

Cost-effectiveness analysis of cinacalcet for haemodialysis patients with moderate-to-severe secondary hyperparathyroidism in China: evaluation based on the EVOLVE trial

OBJECTIVE

As the cost-effectiveness evaluation of cinacalcet and conventional therapy in China has not been reported, the objective of this study was to make a pharmacoeconomic evaluation of cinacalcet specific to the Chinese healthcare setting in patients with moderate-to-severe secondary hyperparathyroidism (SHPT) undergoing dialysis.

DESIGNS

Data from Evaluation of Cinacalcet Therapy to Lower Cardiovascular Events trial were used for this analysis. A semi-Markov model was constructed to estimate quality-adjusted life years (QALYs) and lifetime costs in cinacalcet plus conventional therapy (cinacalcet strategy) compared with conventional therapy (standard strategy), in patients with moderate-to-severe SHPT undergoing dialysis. Treatment effect estimates from the unadjusted intent-to-treat (ITT) analysis and covariate-adjusted ITT analysis were used as the main analyses. Model sensitivity to variations in individual inputs and overall decision uncertainty were assessed through probabilistic sensitivity analyses.

PRIMARY AND SECONDARY OUTCOME MEASURES

Incremental cost-effectiveness ratio (ICER) as measured by cost per QALY gained.

RESULTS

The ICER for cinacalcet strategy was US$44 400 per QALY gained using the covariate-adjusted ITT analysis. Probabilistic sensitivity analysis suggested a 46.2% chance of the ICER being below a willingness-to-pay threshold of US$26 508. Treatment effects from unadjusted ITT analysis yielded an ICER of US$87 210 per QALY. The model was most sensitive to the treatment effect on mortality.

CONCLUSIONS

Existing evidence does not support the cost-effectiveness of cinacalcet strategy in patients with moderate-to-severe SHPT undergoing dialysis when applying a willingness-to-pay threshold of US$26 508 per QALY, whether it is using the treatment effect from covariate-adjusted ITT analysis or unadjusted ITT analysis.

Evaluation of laboratory parameters and symptoms after parathyroidectomy in dialysis patients with secondary hyperparathyroidism

Objectives: The aim of the study was to evaluate the laboratory parameters and symptoms after parathyroidectomy (PTX) in dialysis patients with secondary hyperparathyroidism (SHPT), and to briefly analyze the different therapeutic effects of the three surgical methods.

Methods: A total of 182 dialysis patients who underwent PTX between February 2012 and January 2018 at the Second Affiliated Hospital of Soochow University were included in this study and followed for 12 months. Laboratory parameters such as calcium (Ca), phosphorus (P), alkaline phosphatase (ALP), and intact parathyroid hormone (iPTH) were measured before and after operation. According to the follow-up time and type of operation, we calculated the percentage of laboratory indicators reaching the recommended range of the KDIGO guidelines after surgery. We also analyzed the improvement of bone pain and pruritus, as well as surgical complications.

Results: After the operation, the levels of iPTH, Ca, and P decreased significantly at each time point. ALP increased at the first postoperative week and gradually decreased to normal range after 3 months. Symptoms, such as bone pain and pruritus, were significantly relieved. According to the follow-up time and three surgical methods (subtotal parathyroidectomy, total parathyroidectomy, total parathyroidectomy plus autologous transplantation), we found that the ratio of each laboratory parameter reaching the recommended range of KDIGO guidelines was significantly different.

Conclusion: PTX is a safe and effective therapy for treating SHPT that is refractory to medical therapies and accompanied by related signs and symptoms in dialysis patients. All three operative techniques were effective in controlling SHPT.

Evocalcet: A New Oral Calcimimetic for Dialysis Patients With Secondary Hyperparathyroidism

Patients with chronic kidney disease often develop secondary hyperparathyroidism (SHPT), marked by high levels of circulating parathyroid hormone (PTH) and increased risk of morbidity and mortality. Patients with SHPT are treated with a therapeutic combination that commonly includes calcimimetics, which have recently become popular in clinical settings, and other agents such as vitamin D preparations. Calcimimetics are a drug class that reduces PTH levels by targeting the calcium‐sensing receptor. Cinacalcet, a representative calcimimetic, is widely used; however, a high incidence of upper gastrointestinal (GI) tract‐related adverse events (AEs) can result in insufficient dosage and poor long‐term compliance. The newly approved evocalcet has equivalent efficacy to cinacalcet at a lower clinical dose, with improved bioavailability, fewer upper GI tract‐related AEs, and fewer safety concerns. This review gives an overview of calcimimetic agents, with a special focus on evocalcet, and describes the clinical advantages of evocalcet in the treatment of dialysis patients with SHPT.

Long-term outcomes and management considerations after parathyroidectomy in the dialysis patient

Parathyroidectomy (PTX) remains an important intervention for dialysis patients with poorly controlled secondary hyperparathyroidism (SHPT), though there are only retrospective and observational data that show a mortality benefit to this procedure. Potential consequences that we seek to avoid after PTX include persistent or recurrent hyperparathyroidism, and parathyroid insufficiency. There is considerable subjectivity in defining and diagnosing these conditions, given that we poorly understand the optimal PTH targets (particularly post PTX) needed to maintain bone and vascular health. While lowering PTH after PTX decreases bone turnover, long-term changes in bone activity have been poorly explored. High turnover bone disease, usually present at the time a PTX is considered, often swings to a state of low turnover in the setting of sufficiently low PTH levels. It remains unclear if all low bone turnover equate with disease. However, such changes in bone turnover appear to predispose to vascular calcification, with positive calcium balance after PTX being a potential contributor. We know little of how the post-PTX state resets calcium balance, how calcium and VDRA requirements change or what kind of adjustments are needed to avoid calcium loading. The current consensus cautions against excessive reduction of PTH although there is insufficient evidence-based guidance regarding the management of chronic kidney disease - mineral bone disease (CKD-MBD) parameters in the post-PTX state. This article aims to compile existing research, provide an overview of current practice with regard to PTX and post-PTX chronic management. It highlights gaps and controversies and aims to re-orient the focus to clinically relevant contemporary priorities in CKD-MBD management after PTX.

Calcimimetics and Bundled Reimbursement

Since 2011, the Centers for Medicare & Medicaid Services has provided reimbursement for renal dialysis services furnished to Medicare beneficiaries through a bundled payment system known as the Prospective Payment System. Medications that have no injectable equivalent, known as "oral-only medications," are currently excluded from the bundle and are paid separately through Medicare Part D. Thus, before the development of etelcalcetide, the first injectable calcimimetic, calcimimetics were reimbursed outside the bundle. Etelcalcetide's introduction and approval for use in Medicare triggered a transition payment for a minimum of 2 years that will eventually result in the incorporation of calcimimetics into the dialysis bundle. Consequently, providers may face incentives to reduce calcimimetic use when the transition period has expired. The complexity of bone-mineral management in conjunction with the paucity of evidence-based recommendations in this area makes it difficult to predict the impact of this transition. Because these medications are expensive, a poor transition could have financial ramifications for dialysis organizations and potentially patient health. To ensure that patients are not adversely affected, it is critical that Medicare incorporate these medications into the bundle carefully, with close monitoring of outcomes.

Parathyroidectomy in the Management of Secondary Hyperparathyroidism

Secondary hyperparathyroidism develops in CKD due to a combination of vitamin D deficiency, hypocalcemia, and hyperphosphatemia, and it exists in nearly all patients at the time of dialysis initiation. There is insufficient data on whether to prefer vitamin D analogs compared with calcimimetics, but the available evidence suggests advantages with combination therapy. Calcium derangements, patient adherence, side effects, and cost limit the use of these agents. When parathyroid hormone level persists >800 pg/ml for >6 months, despite exhaustive medical interventions, monoclonal proliferation with nodular hyperplasia is likely present along with decreased expression of vitamin D and calcium-sensing receptors. Hence, surgical parathyroidectomy should be considered, especially if concomitant disorders exist, such as persistent hypercalcemia or hyperphosphatemia, tissue or vascular calcification including calciphylaxis, and/or worsening osteodystrophy. Parathyroidectomy is associated with 15%-57% greater survival in patients on dialysis, and it also improves hypercalcemia, hyperphosphatemia, tissue calcification, bone mineral density, and health-related quality of life. The parathyroidectomy rate in the United States declined to approximately seven per 1000 dialysis patient-years between 2002 and 2011 despite an increase in average parathyroid hormone levels, reflecting calcimimetics introduction and uncertainty regarding optimal parathyroid hormone targets. Hospitalization rates are 39% higher in the first postoperative year. Hungry bone syndrome occurs in approximately 25% of patients on dialysis, and profound hypocalcemia requires high doses of oral and intravenous calcium along with calcitriol supplementation. Total parathyroidectomy with autotransplantation carries a higher risk of permanent hypocalcemia, whereas risk of hyperparathyroidism recurrence is higher with subtotal parathyroidectomy. Given favorable long-term outcomes from observational parathyroidectomy cohorts, despite surgical risk and postoperative challenges, it is reasonable to consider parathyroidectomy in more patients with medically refractory secondary hyperparathyroidism.

Parathyroidectomy decreases neutrophil-to-lymphocyte and platelet-to-lymphocyte ratios

BACKGROUND

Systemic inflammation has been implicated in complications and heightened mortality of patients with secondary hyperparathyroidism. The neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) are widely available surrogate markers of inflammation. This study sought to delineate the changes in NLR and PLR after parathyroidectomy.

METHODS

A total of 213 patients undergoing initial parathyroidectomy from 2010 to 2015 for secondary hyperparathyroidism were identified from a prospectively maintained clinical database. Among 183 patients free of persistent or recurrent disease, follow-up NLR and PLR were available for analysis in 85 patients.

RESULTS

In the whole study population, the baseline NLR was positively correlated with male sex, total white blood cell count, height, serum phosphorus, and calcium-phosphorus product levels. The baseline PLR was positively correlated with platelet count, serum phosphorus, and calcium-phosphorus product levels and negatively associated with patient age. Postoperative parathyroid hormone levels were positively correlated with NLR and PLR at follow-up. For patients who had successful parathyroidectomy, there was a decrease in NLR (P = 0.0006), PLR (P = 0.0003), and platelet count (P = 0.033), whereas hemoglobin significantly increased (P = 0.0002) after surgery. Those with persistent or recurrent hyperparathyroidism had no change in NLR, PLR, hemoglobin, total white blood cell, or platelet count.

CONCLUSIONS

Successful parathyroidectomy is associated with a decrease in NLR and PLR. The modulatory effects of parathyroidectomy on systemic inflammation may partially explain the benefits of surgery in secondary hyperparathyroidism.