Cinacalcet versus standard treatment for chronic kidney disease: a systematic review and meta-analysis

Molecular regulation of calcium-sensing receptor (CaSR)-mediated signaling

Calcium-sensing receptor (CaSR), a family C G-protein-coupled receptor, plays a crucial role in regulating calcium homeostasis by sensing small concentration changes of extracellular Ca2+, Mg2+, amino acids (e.g., L-Trp and L-Phe), small peptides, anions (e.g., HCO3 - and PO4 3-), and pH. CaSR-mediated intracellular Ca2+ signaling regulates a diverse set of cellular processes including gene transcription, cell proliferation, differentiation, apoptosis, muscle contraction, and neuronal transmission. Dysfunction of CaSR with mutations results in diseases such as autosomal dominant hypocalcemia, familial hypocalciuric hypercalcemia, and neonatal severe hyperparathyroidism. CaSR also influences calciotropic disorders, such as osteoporosis, and noncalciotropic disorders, such as cancer, Alzheimer's disease, and pulmonary arterial hypertension. This study first reviews recent advances in biochemical and structural determination of the framework of CaSR and its interaction sites with natural ligands, as well as exogenous positive allosteric modulators and negative allosteric modulators. The establishment of the first CaSR protein-protein interactome network revealed 94 novel players involved in protein processing in endoplasmic reticulum, trafficking, cell surface expression, endocytosis, degradation, and signaling pathways. The roles of these proteins in Ca2+-dependent cellular physiological processes and in CaSR-dependent cellular signaling provide new insights into the molecular basis of diseases caused by CaSR mutations and dysregulated CaSR activity caused by its protein interactors and facilitate the design of therapeutic agents that target CaSR and other family C G-protein-coupled receptors.

Pretransplant Parathyroidectomy in Patients with Severe Secondary Hyperparathyroidism and Long-Term Effectiveness After Kidney Transplantation

Kidney transplantation (KT) is the best option for patients with end-stage renal disease, but recipients still have legacy bone mineral disease from the pretransplant period, especially patients with severe secondary hyperparathyroidism (sHPT). Patients who had severe sHPT and underwent KT were analyzed retrospectively. Two groups were identified (patients with severe sHPT who had parathyroidectomy or calcimimetic before KT). Bone mineral density (BMD) was measured in the first year and last follow-up at the femoral neck, total hip, and lumbar spine using the dual-energy X-ray absorptiometry (DXA). Persistent hyperparathyroidism (perHPT) incidence was significantly higher in the calcimimetic group (75% vs. 40%, p=0.007). In patients with parathyroidectomy, BMDs were higher at femoral neck (0.818±0.114 vs. 0.744±0.134, p=0.04) and lumbar spine (1.005±0.170 vs. 0.897±0.151, p=0.01) at the first assessment. The BMD comparison between patients treated with parathyroidectomy and calcimimetic found a significant difference only in the femoral neck at second evaluation (0.835±0.118 vs. 0.758±0.129; p=0.03). In multivariate, linear regression revealed a positive association between the last BMD of the femoral neck with body mass index (CC: 0.297, 95% CI, 0.002-0.017) and parathyroidectomy (CC: 0.319, 95% CI, 0.021-0.156). Parathyroidectomy is associated with a significantly better femoral neck BMD and a lower incidence of perHPT in patients with severe sHPT.

Effect of Paricalcitol Combined with Cinacalcet on Calcium and Phosphorus Metabolism in Patients Receiving Maintenance Hemodialysis

This study was designed to compare the beneficial effects of paricalcitol combined with or without cinacalcet on calcium and phosphorus metabolism in patients undergoing maintenance hemodialysis (MHD). A total of 140 patients who received MHD in our hospital from March 2021 to March 2022 were randomly divided into a control group (intravenous paricalcitol, n = 70) and a test group (intravenous paricalcitol combined with oral cinacalcet, n = 70). Clinical baseline data and relevant laboratory parameters before treatment were compared. Additionally, calcium, phosphorus, intact parathyroid hormone in serum were measured and compared between the 2 groups before treatment and 1, 2, 3, 4, 5, 6, 9, 10, and 12 months after treatment. As a result, comparison before treatment demonstrated no significant difference in baseline data such as age, sex, and most laboratory parameters between the 2 groups (P > .05), but there was a significant difference in mean corpuscular volume (P < .001). The serum phosphorus level decreased and calcium level increased significantly in the 2 groups after treatment, while the intact parathyroid hormone level showed no significant change within 12 months of treatment (P > .05). In addition, the combined treatment for 6-12 months caused a much lower phosphorus level (P < .05) and higher calcium level (P < .05) than the treatment with paricalcitol alone, and the difference increased with the extension of treatment time. Collectively, paricalcitol combined with cinacalcet, which is more effective than paricalcitol alone, has a positive effect on calcium and phosphorus metabolism in patients receiving MHD.

[Use of cinacalcet in secondary hyperparathyroidism: assessment of nutritional, lipid and inflammatory status in chronic kidney disease]

Introduction

Introduction: observations in cell lines suggest that the use of cinacalcet could be associated with increase in body fat, inflammatory state, and alteration in lipid metabolism. However, when scaling the model to the clinical level, the occurrence of these effects is unknown. Objectives: to analyze the effect of cinacalcet therapy on anthropometric, inflammatory and lipid parameters in renal patients with secondary hyperparathyroidism (SHPT). Methods: observational study with two approaches. The retrospective study included 89 patients who started cinacalcet treatment since 2018 with a maximum follow-up of 36 months. Body mass index (BMI) variables, waist circumference, tricipital skinfold, parathyroid hormone (PTH), and biochemical profile were analyzed. The prospective study included 52 patients who started cinacalcet treatment since 2020 with a 12-month follow-up. BMI, PTH, lipid profile, and PCR variables were analyzed. Results: in the retrospective study, BMI was 27 kg/m2, with 62 % overweight and 65 % of patients with high cardiovascular risk. Cinacalcet reduced PTH by 12 % after six months (p < 0.01) and serum calcium decreased by 3.4 % at the end of follow-up (p = 0.04). According to the prospective study, BMI was 26.8 kg/m2, with 60 % overweight. PTH decreased by 8.4 % after six months. Total cholesterol, LDL cholesterol, and triglycerides decreased by 6.8 %, 12.5 %, and 5.5 %, respectively, at the end of follow-up. Conclusions: the prevalent nutritional status is excess weight. In patients with SHPT, cinacalcet improves PTH control without causing changes in anthropometric, lipid, and inflammatory parameters.

Development and validation of an LC-MS/MS method by one-step precipitation for cinacalcet in human plasma

A sensitive, convenient, rapid and economic liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to determine cinacalcet concentration in human plasma. A stable isotope cinacalcet (cinacalcet-D₃) was selected as internal standard and the analytes were extracted from plasma samples by a one-step precipitation procedure. Chromatography separation was conducted on an Eclipse Plus C18 column by gradient elution with mobile phase of methanol-water-ammonium formate system at a constant flow rate of 0.6 mL/min. Mass spectrometric detection was conducted by multiple reaction monitoring using positive electrospray ionization. Cinacalcet concentrations in human plasma were determined over the concentration range of 0.1-50 ng/mL. The accuracies of lower limit of quantification (LLOQ) and quality control samples were all within the range of 85-115%, and the inter- and intra-batch precisions (CV%) were all within 15%. The average extraction recovery rates were 95.67-102.88%, and the quantification was not interfered by the matrix components. The validated method was successfully applied to determined cinacalcet concentrations in human plasma from secondary hyperparathyroidism patients.

Bone Quality in Chronic Kidney Disease Patients: Current Concepts and Future Directions - Part II

Background

Patients with chronic kidney disease (CKD) have an increased risk of osteoporotic fractures, which is due not only to low bone volume and mass but also poor microarchitecture and tissue quality. The pharmacological and nonpharmacological interventions detailed, herein, are potential approaches to improve bone health in CKD patients. Various medications build up bone mass but also affect bone tissue quality. Antiresorptive therapies strikingly reduce bone turnover; however, they can impair bone mineralization and negatively affect the ability to repair bone microdamage and cause an increase in bone brittleness. On the other hand, some osteoporosis therapies may cause a redistribution of bone structure that may improve bone strength without noticeable effect on BMD. This may explain why some drugs can affect fracture risk disproportionately to changes in BMD.

Summary

An accurate detection of the underlying bone abnormalities in CKD patients, including bone quantity and quality abnormalities, helps in institution of appropriate management strategies. Here in this part II, we are focusing on advancements in bone therapeutics that are anticipated to improve bone health and decrease mortality in CKD patients.

Key Messages

Therapeutic interventions to improve bone health can potentially advance life span. Emphasis should be given to the impact of various therapeutic interventions on bone quality.

Being elderly is not a contraindication of parathyroidectomy for renal hyperparathyroidism and chronic kidney disease-mineral and bone disorder

BACKGROUND

Chronic kidney disease-mineral and bone disorder (CKD-MBD) has more influence in the elderly. Parathyroidectomy remains the golden standard for this situation but has tended to be excluded for older patients for many reasons. This study aimed to evaluate the efficacy and safety of the surgery in the elderly population.

METHODS

156 patients were included and arranged into younger (≦65 years of age, n = 139) and elderly (>65 years of age, n = 17) groups. The change of bone mineral density (BMD) data, recovery potential {[(postoperative BMD) - (preoperative BMD)]/(preoperative BMD) ∗ 100%}, surgical successful rate and related complications were collected.

RESULTS

Both groups exhibited significant postoperative improvement on the BMD results. The recovery potential of the elderly was not lower than the younger group. High success rate and none of persistent vocal palsy, hypocalcemia or any sequela were also observed in the elderly.

CONCLUSIONS

Parathyroidectomy is an effective and safe intervention for the CKD-MBD in the elderly.

Efficacy and safety of cinacalcet compared with other treatments for secondary hyperparathyroidism in patients with chronic kidney disease or end-stage renal disease: a meta-analysis

Background

It is controversial for the effect and safety between cinacalcet and other treatments in treating secondary hyperparathyroidism for patients with chronic kidney disease (CKD) or end-stage renal disease (ESRD).

Methods

Embase, PubMed, and Cochrane Library were searched through Feb 2017. 21 randomized controlled trials were included. We calculated the pooled mean difference (MD), relative risk (RR) and corresponding 95% confidence interval (CI).

Result

Patients received calcimimetic agents had significantly decreased serum parathyroid hormone (MD = − 259.24 pg/mL, 95% CI: − 336.23 to − 182.25), calcium (MD = − 0.92 mg/dL, 95% CI: − 0.98 to − 0.85) and calcium phosphorus product (MD = − 5.97 mg²/dL², 95% CI: − 9.77 to − 2.16) concentration compared with control treatment. However, the differences in cardiovascular mortality and all-cause mortality between calcimimetics agents and control group were not statistically significant. The incidence of nausea (RR = 2.13, 95% CI: 1.62 to 2.79), vomiting (RR = 1.99, 95% CI: 1.78 to 2.23) and hypocalcemia (RR = 10.10, 95% CI: 7.60 to 13.43) in CKD patients with calcimimetics agents was significantly higher than that with control treatment.

Conclusion

Cinacalcet improved the biochemical parameters in CKD patients, but did not improve all-cause mortality and cardiovascular mortality. Moreover, cinacalcet can cause some adverse events.

PTH hypersecretion triggered by a GABAB1 and Ca2+-sensing receptor heterocomplex in hyperparathyroidism

Molecular mechanisms mediating tonic secretion of parathyroid hormone (PTH) in response to hypocalcaemia and hyperparathyroidism (HPT) are unclear. Here we demonstrate increased heterocomplex formation between the calcium-sensing receptor (CaSR) and metabotropic γ-aminobutyric acid (GABA) B₁ receptor (GABA_B1R) in hyperplastic parathyroid glands (PTGs) of patients with primary and secondary HPT. Targeted ablation of GABA_B1R or glutamic acid decarboxylase 1 and 2 in PTGs produces hypocalcaemia and hypoparathyroidism, and prevents PTH hypersecretion in PTGs cultured from mouse models of hereditary HPT and dietary calcium-deficiency. Cobinding of the CaSR/GABA_B1R complex by baclofen and high extracellular calcium blocks the coupling of heterotrimeric G-proteins to homomeric CaSRs in cultured cells and promotes PTH secretion in cultured mouse PTGs. These results combined with the ability of PTG to synthesize GABA support a critical autocrine action of GABA/GABA_B1R in mediating tonic PTH secretion of PTGs and ascribe aberrant activities of CaSR/GABA_B1R heteromer to HPT.

Cinacalcet Treatment Significantly Improves All-Cause and Cardiovascular Survival in Dialysis Patients: Results from a Meta-Analysis

OBJECTIVE

To assess the long-term effects including all-cause mortality, cardiovascular mortality, and fracture incidence, of cinacalcet on secondary hyperparathyroidism (SHPT) in patients on dialysis.

METHODS

PubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched from their inception to October 2018. Randomized controlled trials (RCTs) and cohort design prospective observational studies assessing cinacalcet for the treatment of SHPT in dialysis patients were included. Data extraction was independently completed by 2 authors who determined the methodological quality of the studies and extracted data in duplicate. Study-specific risk estimates were tested by using a fixed effects model.

RESULTS

A total of 14 articles with 38,219 participants were included, of which 10 RCTs with 7,471 participants and 4 prospective observational studies with 30,748 participants fulfilled the eligibility criteria. Compared with no cinacalcet, cinacalcet administration reduced all-cause mortality (relative risk [RR] 0.91, 95% CI 0.89-0.94, p < 0.001) and cardiovascular mortality (RR 0.92, 95% CI 0.89-0.95, p < 0.001), but it did not significantly reduce the incidence of fractures (RR 0.93, 95% CI 0.87-1.00, p = 0.05).

CONCLUSIONS

The results of this meta-analysis indicated that the treatment of SHPT with cinacalcet may in fact reduce all-cause mortality and cardiovascular mortality among patients receiving maintenance dialysis.

MANAGEMENT OF HYPERPARATHYROIDISM IN KIDNEY TRANSPLANTATION CANDIDATES: A NEED FOR CONSENSUS

Objective: To assess the evolving standards of care for hyperparathyroidism in kidney transplant candidates. Methods: An 11-question, Institutional Review Board-approved survey was designed and reviewed by multiple institutions. The questionnaire was made available to the American Society of Transplantation's Kidney Pancreas Community of Practice membership via their online hub from April through July 2019. Results: Twenty percent (n = 41) of kidney transplant centers responded out of 202 programs in the United States. Forty-one percent (n = 17) of respondents believed medical literature supports the concept that a serum parathyroid hormone level greater than 800 pg/mL could endanger the survival of a transplanted kidney and therefore makes transplantation in an affected patient relatively or absolutely contraindicated. Sixty-six percent (n = 27) said they occasionally recommend parathyroidectomy for secondary hyperparathyroidism prior to transplantation, and 66% (n = 27) recommend parathyroidectomy after transplantation based on persistent, unsatisfactory posttransplantation parathyroid hormone levels. Forty-six percent (n = 19) prefer subtotal parathyroidectomy as their choice; 44% (n = 18) had no standard preference. Endocrine surgery and otolaryngology were the most common surgical specialties consulted to perform parathyroidectomy in kidney transplant candidates. The majority of respondents (71%, n = 29) do not involve endocrinologists in the management of kidney transplantation candidates. Conclusion: Our survey shows wide divergence of clinical practice in the area of surgical management of kidney transplantation candidates with hyperparathyroidism. We suggest that medical/surgical societies involved in the transplantation care spectrum convene a multidisciplinary group of experts to create a new section in the kidney transplantation guidelines addressing the collaborative management of parathyroid disease in transplantation candidates. Abbreviations: AACE = American Association of Clinical Endocrinologists; AAES = American Association of Endocrine Surgeons; AHNS = American Head and Neck Society; CKD = chronic kidney disease; CKD-MBD = chronic kidney disease-mineral and bone disorder; ESRD = end-stage renal disease; HPT = hyperparathyroidism; KDIGO = Kidney Disease Improving Global Outcomes; KT = kidney transplantation; KTC = kidney transplant candidate; PTH = parathyroid hormone; PTX = parathyroidectomy; US = ultrasonography.

Cinacalcet plus vitamin D versus vitamin D alone for the treatment of secondary hyperparathyroidism in patients undergoing dialysis: a meta-analysis of randomized controlled trials

BACKGROUND

Secondary hyperparathyroidism (SHPT) is a common and serious complication of chronic kidney disease, particularly in end-stage renal disease. Currently, both cinacalcet and vitamin D are used to treat SHPT via two different mechanisms, but it is still unclear whether the combination use of these two drugs can be a safe and effective alternative to vitamin D alone. Therefore, the aim of this meta-analysis was to assess the efficacy and safety of cinacalcet plus vitamin D in the treatment of SHPT.

METHODS

Four electronic databases, including PubMed, EMBASE, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science, were searched for eligible publications. All randomized-controlled trials comparing cinacalcet plus vitamin D with vitamin D alone in SHPT patients undergoing dialysis were included. Mean difference (MD) with 95% confidence intervals (CIs) and risk ratios (RRs) with 95% CIs were calculated using a random-effects model or fixed-effects model. Sensitivity analysis was conducted by removing any one study successively to estimate the stability of the pooled results, and subgroup analysis was carried out to explore potential sources of heterogeneity, and funnel plots were used to test publication bias.

RESULTS

A total of 8 randomized-controlled trials involving 1480 patients were included in the study. Compared with vitamin D treatment, the combination use of cinacalcet and vitamin D significantly lowered serum calcium (MD - 0.82, 95% CI - 1.02 to - 0.61, P < 0.001), phosphorus (MD - 0.57, 95% CI - 0.97 to - 0.18, P = 0.005), and calcium × phosphorus product (MD - 9.41, 95% CI - 10.00 to - 8.82, P < 0.001). However, there was no difference in serum parathyroid hormone (PTH, MD 43.99, 95% CI - 49.22 to 137.20, P = 0.35), ≥ 30% reduction in PTH (RR 1.02, 95% CI 0.69-1.52, P = 0.91), and PTH achieve 150-300 pg/ml (RR 0.88, 95% CI 0.68-1.15, P = 0.35). Moreover, the combination therapy did not increase the risk of all adverse events, all-cause mortality, diarrhea, muscle spasms, and headache (all P > 0.05), but had a higher risk of hypocalcemia (RR 17.98, 95% CI 5.68-56.99, P < 0.001), and nausea or vomiting (RR 3.47, 95% CI 2.25-5.35, P < 0.001).

CONCLUSIONS

In comparison with vitamin D alone, the combination use of cinacalcet and vitamin D significantly lowered serum calcium, phosphorus, and the calcium × phosphorus product, and did not increase the risk of all adverse events, all-cause mortality, diarrhea, muscle spasms, and headache, whereas had no effect on serum PTH and increased the risk of hypocalcemia and nausea or vomiting. Future studies are needed to assess the effects of cinacalcet plus vitamin D on PTH level, cardiovascular events, and other clinical outcomes in larger samples with longer durations.

Efficacy and safety of cinacalcet and active vitamin D in the treatment of secondary hyperparathyroidism in patients with chronic kidney disease: a network meta-analysis

Background

We conducted a network meta-analysis (NMA) to evaluate the efficacy and safety of cinacalcet, active vitamin D and cinacalcet plus active vitamin D in the treatment of secondary hyperparathyroidism (SHPT) in patients with chronic kidney disease (CKD).

Methods

A systematic literature search was performed using the Cochrane Library, PubMed, EMBASE, Web of Science, Google Scholar, China National Knowledge Internet (CNKI) and Wanfang databases. In total, eight randomized controlled trials (RCTs) with 1,443 patients were eligible for this meta-analysis. Pairwise meta-analysis was performed to evaluate the compliance of intact parathyroid hormone (iPTH), Ca, P, etc., and the mortality and safety of cinacalcet plus active vitamin D and active vitamin D alone. Then, NMA was used to estimate the safety and efficacy of the administration of active vitamin D and different drugs in the control group.

Results

The results of the pairwise meta-analysis revealed that compared with active vitamin D monotherapy, cinacalcet plus active vitamin D did not improve the survival of patients but significantly improved the blood calcium compliance rate [relative risk (RR) =1.82, 95% confidence interval (CI): 1.51-2.21, P<0.00001]. Furthermore, it is worth noting that compared with the corresponding incidence with other treatments, the incidence of vomiting was significantly increased with cinacalcet plus active vitamin D treatment (RR =2.07, 95% CI: 1.18-3.65, P=0.01). Through direct and indirect comparisons, the NMA revealed the following results: (I) compared with oral or intravenous (IV) administration of vitamin D, the solely oral administration of active vitamin D increased mortality, and (II) cinacalcet monotherapy increased the risk of hypocalcemia, and that risk was even higher for cinacalcet plus active vitamin D. However, the results should be treated with caution because the prediction interval (PrI) crossed the invalid line.

Conclusions

This pairwise meta-analysis and NMA provided a comprehensive analysis of the currently utilized CKD-SHPT treatment interventions. This network identified some highly ranked interventions through analyses that were included in a small number of trials; these interventions merit further examination on a larger scale in the context of well-designed RCTs.

Renoprotective Effect of Laminaria japonica Polysaccharide in Adenine-Induced Chronic Renal Failure

Chronic renal failure (CRF) is a major public health problem worldwide. In this work, we investigated the effects of a purified Laminaria japonica polysaccharide (LJP61A) on renal function using an adenine-induced CRF mice model. Results exhibited that adenine treatment caused serious renal pathological damages and elevation of serum creatinine and blood urea nitrogen of mice. However, these changes could be significantly reversed by the administration of LJP61A in a dose-dependent manner. Additionally, LJP61A could dramatically reduce weight loss, improve the urine biochemical index, and regulate the electrolyte disturbance of CRF mice. These results suggest that the renal function of adenine-induced CRF mice can be improved by LJP61A, which might be developed into a potential therapeutic agent for CRF patients.

Successful use of cinacalcet to treat parathyroid-related hypercalcemia in two pediatric patients

Two pediatric patients with different causes of hyperparathyroidism are reported. First patient is a 13-year-old male with severe hypercalcemia due to left upper parathyroid gland adenoma. After successful surgery, calcium and phosphate levels normalized, but parathormone levels remained elevated. Further studies revealed a second adenoma in the right gland. The second patient is a 13-year-old female with uncommon hypercalcemia symptoms. Presence of pathogenic calcium-sensing receptor gene (CASR) mutation was found, resulting in diagnosis of symptomatic familial hypocalciuric hypercalcemia. Cinacalcet, a calcium-sensing agent that increases the sensitivity of the CASR, was used in both patients with successful results.

Discovery and Development of Calcimimetic and Calcilytic Compounds

The extracellular calcium receptor (CaR) is a G protein-coupled receptor (GPCR) and the pivotal molecule regulating systemic Ca²⁺ homeostasis. The CaR was a challenging target for drug discovery because its physiological ligand is an inorganic ion (Ca²⁺) rather than a molecule so there was no structural template to guide medicinal chemistry. Nonetheless, small molecules targeting this receptor were discovered. Calcimimetics are agonists or positive allosteric modulators of the CaR, while calcilytics are antagonists and all to date are negative allosteric modulators. The calcimimetic cinacalcet was the first allosteric modulator of a GPCR to achieve regulatory approval and is a first-in-class treatment for secondary hyperparathyroidism in patients on dialysis, and for hypercalcemia in some forms of primary hyperparathyroidism. It is also useful in treating some rare genetic diseases that cause hypercalcemia. Two other calcimimetics are now on the market (etelcalcetide) or under regulatory review (evocalcet). Calcilytics stimulate the secretion of parathyroid hormone and were initially developed as treatments for osteoporosis. Three different calcilytics of two different chemotypes failed in clinical trials due to lack of efficacy. Calcilytics are now being repurposed and might be useful in treating hypoparathyroidism and several rare genetic diseases causing hypocalcemia. The challenges ahead for medicinal chemists are to design compounds that select conformations of the CaR that preferentially target a particular signalling pathway and/or that affect the CaR in a tissue-selective manner.

The use of cinacalcet hinders the diagnosis of parathyroid carcinoma in a chronic dialysis patient: a case report

Background

Secondary hyperparathyroidism (SHPT) is a common complication in patients receiving chronic dialysis therapy. Although cinacalcet can control parathyroid function and bone turnover, preventing ectopic calcification remains challenging. Cinacalcet can also suppress PTH secretion due to parathyroid carcinoma in the same way as it does for parathyroid hyperplasia in the uremic condition. We present a case of parathyroid carcinoma partially controlled by cinacalcet, in which tumorous calcinosis was successfully resolved by total parathyroidectomy.

Case presentation

A female patient in her forties who had received dialysis for 12 years was referred to our hospital for painful ectopic calcifications on her right hip joint and both knees. Although she had been treated with alfacalcidol and cinacalcet for 2 years, this therapy had been discontinued 6 months earlier as a result of hypercalcemia. The patient exhibited normocalcemia (2.37 mmol/L) and hyperphosphatemia (2.42 mmol/L) with elevated intact parathyroid hormone (707,000 μg/L). Ultrasonography revealed an enlarged parathyroid gland on the left lower side of the thyroid gland. The otolaryngologist surgeons had to perform an en bloc excision to remove this parathyroid gland because of tight adhesions. Histological examination revealed that parathyroid cells had invaded the surrounding skeletal muscle through fibrous capsules, consistent with parathyroid carcinoma. Her joint pain disappeared 2 weeks after parathyroidectomy, and the tumorous calcinosis had largely resolved after 1 year.

Conclusions

Parathyroid carcinoma is a rare cause of hyperparathyroidism in end-stage kidney disease. Our case indicates that the use of cinacalcet hinders the diagnosis of parathyroid carcinoma in a chronic dialysis patient. When uncontrolled hypercalcemia and/or hyperphosphathemia develop during cinacalcet administration, parathyroidectomy should be considered to prevent a vicious exacerbation of ectopic calcification.

Parathyroid Nodular Hyperplasia and Responsiveness to Drug Therapy in Renal Secondary Hyperparathyroidism: An Open Question

The goal of the pharmacological therapy in secondary hyperparathyroidism (SHPT) is to reduce serum levels of parathyroid hormone and phosphorus, to correct those of calcium and vitamin D, to arrest or reverse the parathyroid hyperplasia. However, when nodular hyperplasia or an autonomous adenoma develops, surgery may be indicated. We reviewed the literature with the aim of defining if the echographic criteria predictive of unresponsiveness of SHPT to calcitriol therapy are valid also in the cinacalcet era and if drug therapy may reverse nodular hyperplasia of parathyroid gland (PTG). The responsiveness to therapy and regression of the nodular hyperplasia of PTG remains an open question in the calcimimetic era as well as the cutoff between medical and surgical therapy. Prospective studies are needed in order to clarify if an earlier use of cinacalcet in moderate SHPT might arrest the progression of parathyroid growth and stabilize SHPT.