Secondary hyperparathyroidism in chronic kidney disease: A narrative review focus on therapeutic strategy.

Chronic kidney disease (CKD) affects over 10% of the global population. One crucial complication of CKD is secondary hyperparathyroidism (SHPT), marked by elevated parathyroid hormone levels due to hyperphosphataemia, hypocalcaemia, and low active vitamin D from impaired renal function. SHPT increases risks of bone deformities, vascular calcification, cardiovascular events and mortality. This review examines SHPT treatment strategies in patients with CKD. First-line treatments include phosphate binders, vitamin D receptor activators and calcimimetics. When these fail, invasive options like parathyroidectomy (PTX) and thermal ablation are considered. PTX effectively reduces symptoms and improves radiological outcomes, outperforming medical treatment alone in reducing cardiovascular risk and mortality. Thermal ablation techniques, such as microwave, radiofrequency, laser or high-intensity focused ultrasound, offer less invasive alternatives with promising results. Future research should explore the molecular mechanisms of parathyroid gland hyperplasia and evaluate various treatments' impacts.

Single-cell RNA sequencing reveals transdifferentiation of parathyroid chief cells into oxyphil cells in patients with uremic secondary hyperparathyroidism.

The parathyroid gland is one of the main organs that regulate calcium and phosphorus metabolism. It is mainly composed of chief cells and oxyphil cells. Oxyphil cell counts are low in the parathyroid glands of healthy adults but are dramatically increased in patients with uremia and secondary hyperparathyroidism (SHPT). Increased oxyphil cell counts are related to drug treatment resistance, but the origin of oxyphil cells and the mechanism of proliferation remain unknown. Herein, three types of parathyroid nodules (chief cell nodules, oxyphil cell nodules and mixed nodules, respectively) excised from parathyroid glands of uremic SHPT patients were used for single-cell RNA sequencing (scRNA-seq), other molecular biology studies, and transplantation into nude mice. Through scRNA-seq of parathyroid mixed nodules from three patients with uremic SHPT, we established the first transcriptomic map of the human parathyroid and found a chief-to-oxyphil cell transdifferentiation characterized by gradual mitochondrial enrichment associated with the uremic milieu. Notably, the mitochondrial enrichment and cellular proliferation of chief cell and oxyphil cell nodules decreased significantly after leaving the uremic milieu via transplantation into nude mice. Remarkably, the phenotype of oxyphil cell nodules improved significantly in the nude mice as characterized by decreased mitochondrial content and the proportion of oxyphil cells to chief cells. Thus, our study provides a comprehensive single-cell transcriptome atlas of the human parathyroid and elucidates the origin of parathyroid oxyphil cells and their underlying transdifferentiating mechanism. These findings enhance our understanding of parathyroid disease and may open new treatment perspectives for patients with chronic kidney disease.

Real-World Analysis of Outcomes and Economic Burden in Patients with Chronic Kidney Disease with and without Secondary Hyperparathyroidism among a Sample of the Italian Population.

This real-world analysis evaluated the clinical and economic burden of non-dialysis-dependent CKD patients with and without secondary hyperparathyroidism (sHPT) in Italy. An observational retrospective study was conducted using administrative databases containing a pool of healthcare entities covering 2.45 million health-assisted individuals. Adult patients with hospitalization discharge diagnoses for CKD stages 3, 4, and 5 were included from 1 January 2012 to 31 March 2015 and stratified using the presence/absence of sHPT. Of the 5710 patients, 3119 were CKD-only (62%) and 1915 were CKD + sHPT (38%). The groups were balanced using Propensity Score Matching (PSM). Kaplan-Meier curves revealed that progression to dialysis and cumulative mortality had a higher incidence in the CKD + sHPT versus CKD-only group in CKD stage 3 patients and the overall population. The total direct healthcare costs/patient at one-year follow-up were significantly higher in CKD + sHPT versus CKD-only patients (EUR 8593 vs. EUR 5671, p < 0.001), mostly burdened by expenses for drugs (EUR 2250 vs. EUR 1537, p < 0.001), hospitalizations (EUR 4628 vs. EUR 3479, p < 0.001), and outpatient services (EUR 1715 vs. EUR 654, p < 0.001). These findings suggest that sHPT, even at an early CKD stage, results in faster progression to dialysis, increased mortality, and higher healthcare expenditures, thus indicating that timely intervention can ameliorate the management of CKD patients affected by sHPT.

Advances in the treatment of secondary and tertiary hyperparathyroidism.

Secondary hyperparathyroidism (SHPT) and tertiary hyperparathyroidism (THPT) are common and complicated clinical endocrine diseases. The parathyroid glands maintain endocrine homeostasis by secreting parathyroid hormone to regulate blood calcium levels. However, structural alterations to multiple organs and systems occur throughout the body due to hyperactivity disorder in SHPT and THPT. This not only decreases the patients' quality of life, but also affects mortality. Since current treatments for these diseases remains unclear, we aimed to develop a comprehensive review of advances in the treatment of SHPT and THPT according to the latest relevant researches.

Secondary hyperparathyroidism (CKD-MBD) treatment and the risk of dementia.

BACKGROUND: Elevated parathyroid hormone (PTH) levels have been reported as a potential risk factor for cognitive impairment. Compared with the general population, older adults with end-stage renal disease (ESRD) who are frequently affected by secondary hyperparathyroidism (SHPT) are at increased risk of developing dementia. The main objective of our study was to evaluate if the risk of dementia in older (age ≥66 years) ESRD patients differed if they were treated for SHPT. METHODS: Using the United States Renal Data System and Medicare claims, we identified 189 433 older adults without a diagnosis of dementia, who initiated dialysis between 2006 and 2016. SHPT treatment was defined as the use of vitamin D analogs, phosphate binders, calcimimetics or parathyroidectomy. We quantified the association between treated SHPT and incident dementia during dialysis using a multivariable Cox proportional hazards model with inverse probability weighting, considering SHPT treatment as a time-varying exposure. RESULTS: Of 189 433 older ESRD adults, 92% had a claims diagnosis code of SHPT and 123 388 (65%) were treated for SHPT. The rate of incident dementia was 6 cases per 100 person-years among SHPT treated patients compared with 11 cases per 100 person-years among untreated patients. Compared with untreated SHPT patients, the risk of dementia was 42% lower [adjusted hazard ratio (aHR) = 0.58, 95% confidence interval (CI): 0.56-0.59] among SHPT treated patients. The magnitude of the beneficial effect of SHPT treatment differed by sex (Pinteraction = .02) and race (Pinteraction ≤ .01), with females (aHR = 0.56, 95% CI: 0.54-0.58) and those of Asian (aHR = 0.51, 95% CI: 0.46-0.57) or Black race (aHR = 0.51, 95% CI: 0.48-0.53) having a greatest reduction in dementia risk. CONCLUSION: Receiving treatment for SHPT was associated with a lower risk of incident dementia among older patients with ESRD. This work provides additional support for the treatment of SHPT in older ESRD patients.

A single-center experience of parathyroidectomy in 1500 cases for secondary hyperparathyroidism: a retrospective study.

BACKGROUND: Chronic kidney disease (CKD) is a global public health problem. With the deterioration of renal function, a certain proportion of CKD patients enter the uremic stage, and secondary hyperparathyroidism (SHPT) becomes a challenge. For refractory hyperparathyroidism, parathyroidectomy (PTX) plays a key role in reducing mortality and improving prognosis. Nevertheless, no consensus has been reached on the optimal surgical method. We aimed to provide evidence for the effectiveness of surgical treatment by summarizing the experience from our center. METHODS: Clinical data from 1500 patients undergoing parathyroidectomy were recorded, which included 1419 patients in a total parathyroidectomy without autotransplantation (tPTX) group, 54 patients in a total parathyroidectomy plus autotransplantation (tPTX + AT) group, and 27 patients in the other group. Perioperative basic data, intact parathyroid hormone (i-PTH) levels, serum calcium levels, serum phosphorus levels, pathological reports, coexisting thyroid diseases, short-term outcomes and complications were analyzed. Moreover, postoperative complications were compared between the tPTX and tPTX + AT groups. RESULTS: Parathyroid hormone, serum calcium and phosphorus levels decreased significantly post-surgery. Two patients died during the perioperative period. As the two most common complications, the incidences of severe hypocalcemia and hyperkalemia were 36.20% (543 cases) and 24.60% (369 cases), respectively. Pre-iPTH levels (OR = 1.001, 95% CI: 1.001-1.001, p < 0.01), serum alkaline phosphatase (ALP) levels (OR = 1.002, 95% CI: 1.001-1.002, p < 0.01) and the mass of excised parathyroid gland (OR = 3.06, 95% CI: 1.24-7.55, p = 0.02) were positively associated with postoperative severe hypocalcemia, while age and serum calcium were negatively associated with it. Pathological reports of resected parathyroid and thyroid glands indicated that 96.49% had parathyroid nodular hyperplasia, 13.45% had thyroid nodular hyperplasia, and 4.08% had thyroid papillary carcinoma. CONCLUSIONS: Parathyroidectomy is a safe and effective treatment for refractory secondary hyperparathyroidism. Severe hypocalcemia is the main complication, and coexistent thyroid diseases should never be neglected.

Independent effects of secondary hyperparathyroidism and hyperphosphataemia on chronic kidney disease progression and cardiovascular events: an analysis from the NEFRONA cohort.

BACKGROUND: Secondary hyperparathyroidism (SHPT) is a complication of chronic kidney disease (CKD) and is associated with changes in calcium and phosphate. These related changes have been associated with increased cardiovascular mortality and CKD progression. It is not clear whether negative outcomes linked to SHPT are confounded by such factors. The present study was designed to assess the possible independent effects of SHPT [defined as patients with excessive parathyroid hormone (PTH) levels or on treatment with PTH-reducing agents] on the risk of CKD progression and cardiovascular event (CVE) incidence in CKD patients, as well as whether hypercalcaemia and/or hyperphosphataemia act as effect modifiers. METHODS: The study enrolled 2445 CKD patients without previous CVE from the National Observatory of Atherosclerosis in Nephrology (NEFRONA) cohort (Stage 3, 950; Stage 4, 612; Stage 5, 195; on dialysis, 688). Multivariate logistic and Fine and Gray regression analysis were used to determine the risk of patients suffering CKD progression or a CVE. RESULTS: The prevalence of SHPT in the cohort was 65.6% (CKD Stage 3, 54.7%; CKD Stage 4, 74.7%; CKD Stage 5, 71.4%; on dialysis, 68.6%). After 2 years, 301 patients presented CKD progression. During 4 years of follow-up, 203 CVEs were registered. Patients with SHPT showed a higher adjusted risk for CKD progression and CVE. Furthermore, hyperphosphataemia was shown to be an independent risk factor in both outcomes and did not modify SHPT effect. No significant interactions were detected between the presence of SHPT and hypercalcaemia or hyperphosphataemia. CONCLUSIONS: We conclude that SHPT and hyperphosphataemia are independently associated with CKD progression and the incidence of CVE in CKD patients.

The impact of CASR A990G polymorphism in response to cinacalcet treatment in hemodialysis patients with secondary hyperparathyroidism.

The objective of this study was to determine the impact of calcium sensing receptor (CASR) A990G genetic polymorphism on parathyroid hormone (PTH) lowering response to cinacalcet treatment when controlling for significant influencing clinical factors. This retrospective study was conducted on 135 Thai hemodialysis (HD) patients with secondary hyperparathyroidism (SHPT). CASR A990G genotypes were determined. The patients were identified as either G carriers (heterozygous or homozygous CASR 990G allele carriers) or noncarriers (homozygous CASR 990A carriers). Tested covariates were baseline PTH level (bPTH), baseline serum phosphate (bPhos), baseline serum calcium (bCa), baseline calcitriol equivalent dose (bCtriol), baseline ergocalciferol dose (bErgo), and age. The ANCOVA showed that intact PTH levels after 12 weeks of cinacalcet treatment (PTHw12) was significantly lower among G carriers compared with noncarriers after controlling for bPTH, bPhos, bCtriol, and bErgo (F(1, 127) = 15.472, p < 0.001), with the adjusted mean difference of 253.7 pg/mL. The logistic regression analysis revealed that the odds of a G carrier achieving 30% PTH reduction after 12-week cinacalcet treatment were 3.968 times greater than the odds for a noncarrier after adjusting for bPhos, bCtriol, and age. In conclusion, the CASR A990G polymorphism significantly influences cinacalcet response in HD patients with SHPT.

Health Care Costs in Patients with and without Secondary Hyperparathyroidism in Spain.

OBJECTIVE: To analyze the economic burden of secondary hyperparathyroidism (sHPT) in Spain by quantifying differences in costs of pharmacological treatments and associated cardiovascular events (CVE) between renal patients with and without sHPT. METHODS: We used data collected in the NEFRONA cohort study and obtained treatment and CVE costs from the BOT PLUS database and Hospital Discharge Records in the Spanish Health System (CMBD-H), respectively. We examined data from 2445 renal patients followed during 2 years for chronic kidney disease (CKD) progression and 4 years for CVE, stratifying by presence of sHPT. Patient characteristics, administered treatments and CVE were directly extracted from NEFRONA registries. Dosage for each treatment regimen was assumed based on guidelines and multiplied by official unit costs to obtain treatment costs. Costs of CVE were based on ICD-9-CM. RESULTS: Prevalence of sHPT in the cohort was 65.6% (63.6; 67.6). Average yearly pharmacological costs for patients without sHPT were 610.33€, while costs were 1483.17€ for sHPT patients (average increase of 143.0%). Two hundred three patients registered CVE, resulting in 4-year average costs of 582.57€ for non-sHPT patients compared to 941.87€ for sHPT patients (61.7% average increase). Bivariate analyses considering presence of dialysis, hypercalcemia or hyperphosphatemia and stratified by sHPT showed higher costs for sHPT patients. CONCLUSIONS: These results show that sHPT is associated with substantially higher costs of both, pharmacological treatments and associated CVEs. Preventing the development of sHPT with early management in the course of CKD could possibly lead to better health outcomes and cost balance for health care systems.

Current treatment options for secondary hyperparathyroidism in patients with stage 3 to 4 chronic kidney disease and vitamin D deficiency.

Introduction: Secondary hyperparathyroidism (SHPT) represents a complication of chronic kidney disease (CKD). Vitamin D system is altered since early CKD, and vitamin D deficiency is an established trigger of SHPT. Although untreated SHPT may degenerate into tertiary hyperparathyroidism with detrimental consequences in advanced CKD, best treatments for counteracting SHPT from stage 3 CKD are still debated. Enthusiasm on prescription of vitamin D receptor activators (VDRA) in non-dialysis renal patients, has been mitigated by the risk of low bone turnover and positive calcium-phosphate balance. Nutritional vitamin D is now suggested as first-line therapy to treat SHPT with low 25(OH)D insufficiency. However, no high-grade evidence supports the best choice between ergocalciferol, cholecalciferol, and calcifediol (in its immediate or extended-release formulation).Areas covered: The review discusses available data on safety and efficacy of nutritional vitamin D, VDRA and nutritional therapy in replenishing 25(OH)D deficiency and counteracting SHPT in non-dialysis CKD patients.Expert opinion: Best treatment for low 25(OH)D and SHPT remains unknown, due to incomplete understanding of the best homeostatic, as mutable, adaptation of mineral metabolism to CKD progression. Nutritional vitamin D and nutritional therapy appear safest interventions, whenever contextualized with single-patient characteristics. VDRA should be restricted to uncontrolled SHPT by first-line therapy.

Decreasing Surgical Management of Secondary Hyperparathyroidism in the United States.

BACKGROUND: Secondary hyperparathyroidism (SHPT) commonly occurs in end-stage renal disease (ESRD), leading to vascular calcification and increased mortality. For SHPT refractory to medical management, parathyroidectomy improves symptoms and decreases mortality. Medical management has changed with the release of new guidelines and advent of novel medications. We investigate recent national trends in parathyroidectomy for SHPT. MATERIALS AND METHODS: We used the National/Nationwide Inpatient Sample from 2004 to 2016 to identify hospitalizations including parathyroidectomy for SHPT and calculated parathyroidectomy rates utilizing data from the United States Renal Data System. Subgroup analysis was conducted by race. Risk factors for in-hospital mortality were identified with purposeful selection and multivariable logistic regression. RESULTS: From 2004 to 2016, the rate of parathyroidectomies for SHPT per 1000 ESRD patients decreased from 6.07 (95% CI: 4.83-7.32) to 3.67 (95% CI: 3.33-4.00). Black patients underwent parathyroidectomy for SHPT at a 1.8-fold higher rate than white and Hispanic patients (5.59 versus 3.04 and 3.07). Almost all tracked comorbidities increased in prevalence. In-hospital mortality trended lower (1.5% to 0.8%, P = 0.051). Risk factors for in-hospital mortality included weight loss (OR 4.19, 95% CI: 2.00-8.78) and cardiac arrhythmia (OR 3.38, 95% CI: 1.66-6.91), while additional calendar year (OR = 0.87, 95% CI: 0.80-0.95) was protective. CONCLUSIONS: The etiology of the declining parathyroidectomy rate for SHPT is unclear; possible factors include changing guidelines emphasizing medical management, widespread availability of cinacalcet, changing practice patterns, and inadequate surgical referral.

Practice variation in the treatment of patients with renal hyperparathyroidism: a survey-based study in the Netherlands.

BACKGROUND: Renal hyperparathyroidism is a disease entity that is complex and poorly understood. Although there are guidelines regarding how to manage this patient group, evidence is scarce. Therefore, this survey-based study aims to map the physicians' attitude in terms of preference for management of renal hyperparathyroidism and the influence of patient and respondent factors. METHODS: A survey was sent to Dutch societies of nephrology, endocrinology, and surgeons with interest in endocrine surgery. The survey consisted of eight case vignettes of renal hyperparathyroidism patients who were on hemodialysis and suitable for kidney transplantation, and varied in one of three patient variables import for decision making: age (40 vs. 65 years), parathyroid hormone (40 vs. 90 pmol/L), and serum calcium level (2.25 vs. 2.8 mmol/L). For each case, respondents could choose between maintaining conservative treatment (active vitamin D metabolites), calcimimetics, or subtotal parathyroidectomy as their treatment of choice. Categorical multilevel logistic models were used to investigate the association of patient and respondent variables with treatment preference. The influence of patient variables was determined independently of each other and by means of logistic regression the probabilities of treatment choice were calculated. RESULTS: In total, 115 surveys were included in the analysis. In 6 out of 8 cases, less than two-thirds of respondents agreed on the most favoured treatment. Among patient characteristics, the main disincentive for respondents not to choose conservative therapy was an elevated serum calcium level (subtotal parathyroidectomy vs conservative OR 93.1, 95%-CI: 48.39-179.07 and calcimimetics vs conservative OR 31.2 95%-CI: 18.58-52.30). Additionally, the most significant treatment differences were found between medical specialties and the experience of the respondents, expressed as the amount of cases the physician was involved in during the past year. CONCLUSIONS: Elevated serum calcium levels were widely recognized and the prime reason for respondents to abandon conservative treatment. However, considerable disagreement in treatment preferences remained throughout the cases, demonstrating the current literature available being inconclusive in guiding physicians. Therefore, a high-quality trial comparing subtotal parathyroidectomy to medical treatment is needed to determine optimal treatment.

A New Approach to Tertiary Hyperparathyroidism: Percutaneous Embolization: Two Case Reports.

Secondary hyperparathyroidism is one of the most common complications of chronic kidney failure. If prolonged, parathyroid hormone release gains autonomy and tertiary hyperparathyroidism with parathyroid adenoma or hyperplasia can be develop. Tertiary hyperparathyroidism is associated with increased risk of mortality and morbidity; thus, treatment is recommended. Medical treatment includes phosphate binders, vitamin D analogues, and calcimimetic agents. Most cases of tertiary hyperparathyroidism can be controlled with medical treatment. When medical treatment options prove insufficient, parathyroidectomy is recommended. However, recurrence after parathyroidectomy is possible, which requires an alternative treatment. We present our percutaneous embolization experience, which has not been tried in the treatment of tertiary hyperparathyroidism in renal transplantation patients diagnosed with tertiary hyperparathyroidism.

Timing of parathyroidectomy for tertiary hyperparathyroidism with end-stage renal disease: A cost-effectiveness analysis.

BACKGROUND: Tertiary hyperparathyroidism associated with end-stage renal disease is characterized by progression from secondary hyperparathyroidism to an autonomous overproduction of parathyroid hormone that leads to adverse health outcomes. Rates of parathyroidectomy (PTX) have decreased with the use of calcimimetics. Optimal timing of PTX in relation to kidney transplant remains controversial. We aimed to identify the most cost-effective strategy for patients with tertiary hyperparathyroidism undergoing kidney transplant. METHODS: We constructed a patient level state transition microsimulation to compare 3 management schemes: cinacalcet with kidney transplant, cinacalcet with PTX before kidney transplant, or cinacalcet with PTX after kidney transplant. Our base case was a 55-year-old on dialysis with tertiary hyperparathyroidism awaiting kidney transplant. Outcomes, including quality-adjusted life years, surgical complications, and mortality, were extracted from the literature, and costs were estimated using Medicare reimbursement data. RESULTS: Our base case analysis demonstrated that cinacalcet with PTX before kidney transplant was dominant, with a lesser cost of $399,287 and greater quality-adjusted life years of 10.3 vs $497,813 for cinacalcet with PTX after kidney transplant (quality-adjusted life years 9.4) and $643,929 for cinacalcet with kidney transplant (quality-adjusted life years 7.4). CONCLUSION: Cinacalcet alone with kidney transplant is the least cost-effective strategy. Patients with end-stage renal disease-related tertiary hyperparathyroidism should be referred for PTX, and it is most cost-effective if performed prior to kidney transplant.

Corneal and Conjunctival Calcification in a Dialysis Patient Reversed by Parathyroidectomy.

Mineral and bone metabolism disorders are relatively common among patients with end-stage renal disease on maintenance hemodialysis. Corneal and conjunctival calcification is the main extravascular site for calcification. Recently, this form of calcification has been linked to vascular calcification. Secondary hyperparathyroidism can lead to high levels of calcium and phosphorus and increase the risk of calcification. Here, we report a case of a 38-year-old female with severe hyperparathyroidism who underwent eye examination before and after parathyroidectomy. Anterior segment optical coherence tomography showed an improvement in the number and size of ocular calcifications 6 months after surgery. This case calls attention to the importance of eye examination in patients on dialysis and brings the possibility of recovery of calcification in a short-term follow-up.

Recent advances in understanding and managing secondary hyperparathyroidism in chronic kidney disease.

Secondary hyperparathyroidism is a complex pathology that develops as chronic kidney disease progresses. The retention of phosphorus and the reductions in calcium and vitamin D levels stimulate the synthesis and secretion of parathyroid hormone as well as the proliferation rate of parathyroid cells. Parathyroid growth is initially diffuse but it becomes nodular as the disease progresses, making the gland less susceptible to be inhibited. Although the mechanisms underlying the pathophysiology of secondary hyperparathyroidism are well known, new evidence has shed light on unknown aspects of the deregulation of parathyroid function. Secondary hyperparathyroidism is an important feature of chronic kidney disease-mineral and bone disorder and plays an important role in the development of bone disease and vascular calcification. Thus, part of the management of chronic kidney disease relies on maintaining acceptable levels of mineral metabolism parameters in an attempt to slow down or prevent the development of secondary hyperparathyroidism. Here, we will also review the latest evidence regarding several aspects of the clinical and surgical management of secondary hyperparathyroidism.