Functional evaluation of a novel nonsense variant of the calcium-sensing receptor gene leading to hypocalcemia.

OBJECTIVE: The calcium-sensing receptor (CASR) gene encodes a G protein-coupled receptor crucial for calcium homeostasis. Gain-of-function CASR variants result in hypocalcemia, while loss-of-function variants lead to hypercalcemia. This study aims to assess the functional consequences of the novel nonsense CASR variant [c.2897_2898insCTGA, p.(Gln967*) (Q967*)] identified in adolescent patient with chronic hypocalcemia, a phenotype expected for a gain-of-function variants. DESIGN AND METHODS: To functionally characterize the Q967* mutant receptor, both wild-type (WT) and mutant CASR were transiently transfected into HEK293T cells and calcium-sensing receptor (CaSR) protein expression and functions were comparatively evaluated using multiple read-outs. RESULTS: Western blot analysis revealed that the CaSR mutant protein displayed a lower molecular weight compared with the WT, consistent with the loss of the last 122 amino acids in the intracellular domain. Mitogen-activated protein kinase activation and serum responsive element luciferase assays demonstrated that the mutant receptor had higher baseline activity than the WT. Extracellular-signal-regulated kinase/c-Jun N-terminal kinase phosphorylation, however, remained consistently high in the mutant, without significant modulations following exposure to increasing extracellular calcium (Ca2+o) levels, suggesting that the mutant receptor is more sensitive to Ca2+o compared with the WT. CONCLUSIONS: This study provides functional validation of the pathogenicity of a novel nonsense CASR variant, resulting in an abnormally hyperfunctioning protein consistent with the patient's phenotype. Functional analyses indicate that mutant receptor is constitutively active and poorly sensitive to increasing concentrations of extracellular calcium, suggesting that the cytoplasmic tail may contain elements regulating signal transduction.

Increased risk of hypocalcemia with decreased kidney function in patients prescribed bisphosphonates based on real-world data from the MID-NET® in Japan: a new-user cohort study.

BACKGROUND: In the post-marketing stage, cases of hypocalcemia associated with bisphosphonate preparations (BPs) have been reported in patients with decreased kidney function, despite warning against use of BPs in such patients in the package insert (PI) of Japan. The purpose of this study was to investigate the safety of BPs in patients with decreased kidney function. METHODS: The cohort study was conducted in patients with osteoporosis and newly prescribed bisphosphonate utilizing real-world data from MID-NET® in Japan. The adjusted hazard ratios (aHRs) for hypocalcemia (a corrected serum Ca level < 8.00 mg/dL) relative to the normal group were calculated in each decreased kidney function group (mild, moderate or severe group). RESULTS: A total of 14,551 patients were included in the analysis, comprising 2,601 (17.88%) with normal (eGFR ≥ 90 mL/min/1.73m2), 7,613 (52.32%) with mild (60 ≤ eGFR < 90 mL/min/1.73m2), 3,919 (26.93%) with moderate (30 ≤ eGFR < 60 mL/min/1.73m2), and 418 (2.87%) with severe kidney function (eGFR < 30 mL/min/1.73m2). The aHRs (95% confidence interval) for hypocalcemia were 1.85 (0.75-4.57), 2.30 (0.86-6.21), and 22.74 (8.37-61.78) in the mild, moderate, and severe groups, respectively. The increased risk of hypocalcemia depending on kidney function was also observed even when calculating the aHR for each specific BP such as alendronate sodium hydrate, minodronic acid hydrate, and sodium risedronate hydrate. Furthermore, similar results were obtained in the sensitivity analysis by altering the outcome definition to a 20% or more reduction in corrected serum Ca level from the baseline, as well as when focusing on patients with more than one laboratory test result per 30 days during the follow-up period. CONCLUSIONS: These findings suggest that the risk of hypocalcemia during BP prescription is higher in patients with decreased kidney function, particularly those with severely decreased kidney function. The quantitative real-world evidence on the safety risk of BPs obtained in this study has led to the PI revision describing a relationship between hypocalcemia risk and decreased kidney function as a regulatory action in Japan and will contribute to promoting the proper use of BPs with appropriate risk management in clinical practice.

Further delineation of phenotype and genotype of Kenny-Caffey syndrome type 2 (phenotype and genotype of KCS type 2).

BACKGROUND: Kenny-Caffey syndrome type 2 (KCS2) is an extremely rare inherited disorder characterized by proportionate short stature, skeletal defects, ocular and dental abnormalities, and transient hypocalcemia. It is caused by variants in FAM111A gene. Diagnosis of KCS2 can be challenging because of its similarities to other syndromes, the absence of clear hallmarks and the deficient number of genetically confirmed cases. Here, we aimed to further delineate and summarize the genotype and phenotype of KCS2, in order to get a better understanding of this rare disorder, and promote early diagnosis and intervention. METHODS: We present clinical and genetic characteristics of eight newly affected individuals with KCS2 from six families, including one family with three individuals found to be a father-to-daughter transmission, adding to the limited literature. Furthermore, we performed a review of genetically confirmed KCS2 cases in PubMed, MEDLINE and CNKI databases. RESULTS: There were six females and two males in our cohort. All the patients presented with short stature (100.0%). Clinical manifestations included ocular defects such as hypermetropia (5/8), dental problems such as defective dentition (3/8) and dental caries (3/8), skeletal and brain anomalies such as delayed closure of anterior fontanelle (6/8), cerebral calcification (3/8), cortical thickening (3/8) and medullary stenosis (4/8) of tubular bones. Endocrinologic abnormalities included hypoparathyroidism (5/8) and hypocalcemia (3/8). One male patient had micropenis and microorchidism. All cases harboured missense variants of FAM111A, and nucleotides c.1706 arose as a mutational hotspot, with seven individuals harbouring a c.1706G>A (p.Arg569His) variant, and one child harbouring a c.1531T>C (p.Tyr511His) variant. Literature review yielded a total of 46 patients from 20 papers. Data analysis showed that short stature, hypoparathyroidism and hypocalcemia, ocular and dental defects, skeletal features including cortical thickening and medullary stenosis of tubular bones, and seizures/spasms were present in more than 70% of the reported KCS2 cases. CONCLUSION: We provide detailed characteristics of the largest KCS2 group in China and present the first genetically confirmed instance of father-to-daughter transmission of KCS2. Our study confirms that Arg569His is the hot spot variant and summarizes the typical phenotypes of KCS2, which would help early diagnosis and intervention.

Multiple pathological fractures and muscle atrophy caused by a parathyroid carcinoma with postoperative hungry bone syndrome: A case report.

BACKGROUND: Parathyroid carcinoma (PC) is a rare endocrine malignancy causing pathological changes such as abnormal bone metabolism, elevated serum calcium, and impaired renal function, and uncontrollable hypercalcemia is the main cause of death in PC patients. The diagnosis of PC is challenging and relying on postoperative histopathology. Radical surgery at the first time is the only effective therapy to cure PC. Hungry bone syndrome (HBS) is a relatively uncommon complication of parathyroidectomy characterized by profound and prolonged hypocalcemia, timely electrolyte monitoring and alternative interventional protocols can prevent symptomatic hypocalcemia. CASE: A 57-year-old man presented with multiple pathological fractures and muscle atrophy as the main symptoms accompanied by bone pain, hypercalcemia, elevated parathyroid hormone (PTH), and an enlarged left-sided neck mass. After consultation of multidisciplinary team, he was treated conservatively with plaster bandage fixation and infusion of intravenous zoledronic acid; and then complete resection of parathyroid mass + removal of involved tissue structures + left thyroid and isthmus lobectomy + lymph node dissection in the VI region in left neck were performed. The postoperative histopathology suggested a diagnosis of parathyroid carcinoma. Calcium and fluid supplementation and oral levothyroxine tablets were given postoperatively. Unexpectedly, the patient's PTH level decreased rapidly at 24 h postoperative, and serum calcium and phosphorus decreased continuously, and he felt numb around perioral sites and fingertips, which considered to be postoperative HBS complicated by parathyroidectomy. Then, a large amount of calcium supplementation and vitamin D were given timely and the patient got better at 1 month postoperatively. At 9-month postoperative, his bone pain and fatigue were significantly relieved compared with before with calcium, phosphorus, and PTH levels at normal range. CONCLUSION: The possibility of parathyroid disease, particularly PC, should be considered in the presence of multiple pathological fractures, muscle atrophy, generalized bone pain, hypercalcemia, and clear neck mass. Radical resection of the tumor lesions at the first surgery is a key element affecting the prognosis of PC, and the effective management of preoperative hypercalcemia and postoperative HBS is also of great significance for improving prognosis.

Dilated cardiomyopathy due to hypocalcaemia: a case report.

BACKGROUND: Hypocalcaemia is a rare, but reversible, cause of dilated cardiomyopathy causing heart failure. Several case reports have been reported on reversible cardiomyopathy secondary to hypocalcaemia. CASE PRESENTATION: We report a case of 54-year-old female Sri Lankan patient who presented with shortness of breath and was diagnosed with heart failure with reduced ejection fraction due to dilated cardiomyopathy. The etiology for dilated cardiomyopathy was identified as hypocalcemic cardiomyopathy, secondary to primary hypoparathyroidism, which was successfully treated with calcium and vitamin D replacement therapy. CONCLUSION: This adds to literature of this rare cause of reversible cardiomyopathy secondary to hypocalcemia reported from the South Asian region of the world. This case highlights the impact of proper treatment improving the heart failure in patients with hypocalcemic cardiomyopathy.

Predictive analysis of severe hypocalcemia following total parathyroidectomy for renal secondary hyperparathyroidism.

OBJECTIVE: This study aimed to evaluate the incidence and identify risk factors for severe hypocalcemia following total parathyroidectomy (TPTX) in patients with renal secondary hyperparathyroidism (SHPT). PATIENTS AND METHODS: We included patients undergoing maintenance hemodialysis or peritoneal dialysis who underwent TPTX from January 1, 2018, to April 30, 2023. Participants were categorized into groups based on postoperative corrected serum calcium levels: severe hypocalcemia (<1.8 mmol/L) and non-severe hypocalcemia (≥1.8 mmol/L). We conducted univariate analyses of demographic and laboratory data to identify potential risk factors, which were further analyzed using a binary logistic regression model. RESULTS: Significant associations were observed with age, dialysis duration exceeding five years, type of dialysis (peritoneal dialysis), lower preoperative corrected serum calcium, elevated preoperative intact parathyroid hormone (iPTH), and increased preoperative alkaline phosphatase (ALP) levels (all p<0.05). Age, preoperative iPTH, and ALP levels were identified as independent risk factors for severe hypocalcemia post-TPTX. CONCLUSIONS: Younger patients with renal SHPT who have elevated preoperative iPTH and ALP levels are at an increased risk of experiencing severe hypocalcemia following TPTX. These findings underscore the importance of careful preoperative assessment and monitoring to mitigate the risk of this complication.

The application of autofluorescence system contributes to the preservation of parathyroid function during thyroid surgery.

PURPOSE: The purpose of this study was to investigate the impact of autofluorescence technology on postoperative parathyroid function and short-term outcomes in patients undergoing thyroid surgery. METHODS: A total of 546 patients were included in the study, with 287 in the conventional treatment group and 259 in the autofluorescence group. Both groups underwent central lymph node dissection, which is known to affect parathyroid function. Short-term outcomes, including rates of postoperative hypocalcemia and parathyroid dysfunction, serum calcium and PTH levels on the first postoperative day, as well as the need for calcium supplementation, were analyzed. A multivariable analysis was also conducted to assess the impact of autofluorescence on postoperative parathyroid dysfunction, considering factors such as age, BMI, and preoperative calcium levels. RESULTS: The autofluorescence group demonstrated significantly lower rates of postoperative hypocalcemia and parathyroid dysfunction compared to the conventional treatment group. The autofluorescence group also had better serum calcium and PTH levels on the first postoperative day, and a reduced need for calcium supplementation. Surprisingly, the use of autofluorescence technology did not prolong surgical time; instead, it led to a shorter hospitalization duration. The multivariable analysis showed that autofluorescence significantly reduced the risk of postoperative parathyroid dysfunction, while factors such as age, BMI, and preoperative calcium levels did not show a significant correlation. CONCLUSION: This study provides evidence that autofluorescence technology can improve the preservation of parathyroid function during thyroid surgery, leading to better short-term outcomes and reduced postoperative complications. The findings highlight the potential of autofluorescence as a valuable tool in the management of parathyroid hypofunction. Further research and validation are needed to establish the routine use of autofluorescence technology in the thyroid.

Effects of Extracellular Calcium Concentration on Hepatic Ischemia-Reperfusion Injury in a Rat Model.

OBJECTIVES: Hypocalcemia is frequently identified during liver transplant. However, supplementation of extracellular calcium could induce increased intracellular calcium concentration, as a potential factor for injury to the liver graft. We evaluated the effects of regulating extracellular calcium concentrations on hepatic ischemia-reperfusion injury. MATERIALS AND METHODS: We randomly divided 24 Sprague-Dawley rats into 3 groups: group C received normal saline (n = 8), group L received citrate to induce hypocalcemia (n = 8), and group L-Co received citrate followed by calcium gluconate to ameliorate hypocalcemia (n = 8). Liver enzyme levels and extracellular calcium were measured before surgery, 1 hour after ischemia, and 2 hours after reperfusion. The primary outcome was liver enzyme levels measured 2 hours after reperfusion. In addition, we evaluated intracellular calcium levels, lactate dehydrogenase activity, and histopathological results in liver tissue. RESULTS: Three groups demonstrated significant differences in extracellular calcium concentrations, but intracellular calcium concentrations in liver tissue were not significantly different. Group L showed significantly lower mean arterial pressure than other groups at 1 hour after ischemia (93.6 ± 20.8 vs 69.4 ± 14.2 vs 86.6 ± 10.4 mmHg; P = .02, for group C vs L vs L-Co, respectively). At 2 hours after reperfusion, group L showed significantly higher liver enzymes than other groups (aspartate aminotransferase 443.0 ± 353.2 vs 952.3 ± 94.8 vs 502.4 ± 327.3 U/L, P = .01; and alanine aminotransferase 407.9 ± 406.5 vs 860.6 ± 210.9 vs 333.9 ± 304.2 U/L, P = .02; for group C vs L vs L-Co, respectively). However, no significant difference was shown in lactate dehydrogenase and histological liver injury grade. CONCLUSIONS: Administering calcium to rats with hypocalcemia did not increase intracellular calcium accumulation but instead resulted in less hepatic injury compared with rats with low extracellular calcium concentrations in this rat model study.

Perioperative outcomes of bilateral axillo-breast approach robotic thyroidectomy (BABART) versus minimally invasive thyroidectomy (MIT): a systematic review and meta-analysis.

Minimally invasive thyroidectomy (MIT) is increasingly being used for the thyroid tumors. The comparison of bilateral axillo-breast approach robotic thyroidectomy (BABART) with other MIT has not yet led to a unified conclusion with regard to surgical outcomes. To conduct a systematic review and meta-analysis of the literature on the surgical outcomes of BABART compared with MIT. We performed a systematic search in PubMed, Web of Science, Embase and Cochrane Library database for randomized control trials (RCTs) and non-RCTs that compare BABART to MIT. The primary outcomes included perioperative, postoperative complications. The odds ratio (OR) and mean difference (MD) were applied for the comparison of dichotomous and continuous variables with 95% confidence intervals (CIs). Nine studies, comprising 3645 patients, were included in the meta-analysis. Our findings indicated that there were no significant differences in hospital stay, number of retrieved lymph nodes, recurrent laryngeal nerve (RLN) injury, and vocal cord dysfunction between BABRT and MIT. However, BABART was associated with a shorter operation time (MD = - 21.45 min, 95% CI [- 47.27, 4.38], p = 0.1) and lower rate of permanent hypoparathyroidism (OR = 0.42, 95% CI [0.20, 0.88], p = 0.02). Additionally, the MIT group had reduced postoperative pain score (MD = 0.45, 95% CI [0.02, 0.88], p = 0.04) and lower rate of hypocalcemia (OR = 2.31, 95% CI [1.04, 5.13], p = 0.04) than the BABART group. In comparison with MIT, BABART exhibits better results in terms of operative time and the rate of permanent hypoparathyroidism, with no significant difference in hospital stay, number of retrieved lymph nodes, RLN injury, and vocal cord dysfunction. However, the postoperative pain score and the rate of hypocalcemia of MIT are slightly better that of BABART.

A Rare Case of Neonatal Hypomagnesemia with Secondary Hypocalcemia Caused by a Novel Homozygous TRPM6 Gene Variant.

BACKGROUND Familial hypomagnesemia with secondary hypocalcemia (HSH) is a rare autosomal recessive disorder (OMIM# 602014) caused by mutations in the gene encoding transient receptor potential melastatin 6 (TRPM6)) on chromosome 9q22, a channel involved in epithelial magnesium resorption. While a plethora of studies have delineated various clinical manifestations pertinent to this mutation, the literature is devoid of connections between TRPM6 mutations and bleeding diathesis, or sudden infant death syndrome (SIDS). This report presents a case of familial HSH associated with the novel homozygous TRPM6 gene variant c.5281C>G p. (Arg1761Gly) chr9: 77354845. CASE REPORT This report details a 26-day-old neonate, born full term with optimal Apgar scores, who experienced an abrupt emergence of apnea, cyanosis, bilateral nasal bleeding, and diminished alertness. Despite the neonate's initially unremarkable clinical birth indicators, a meticulous assessment unveiled a pronounced family history of SIDS, including a sibling previously diagnosed with hypomagnesemia. Laboratory examination of the infant demonstrated severe hypomagnesemia and hypocalcemia, conditions which were promptly ameliorated following intravenous administration of magnesium and calcium. Whole-exome sequencing identified a homozygous TRPM6 gene mutation c.5281C>G p. (Arg1761Gly) at chr9: 77354845. This gene is crucial for magnesium regulation. The mutation involves a cytosine-to-guanine shift, resulting in an arginine to glycine amino acid substitution at position 1761 of the TRPM6 protein. CONCLUSIONS This report has highlighted that infantile hypomagnesemia may be associated with symptoms and signs that can mimic infection, or it can present with seizures. Although familial HSH is a rare genetic disorder that can be identified by genetic testing, correction of hypomagnesemia is the most important and immediate clinical management strategy.

A nomogram prediction model for hungry bone syndrome in dialysis patients with secondary hyperparathyroidism after total parathyroidectomy.

OBJECTIVE: Secondary hyperparathyroidism (SHPT) is a common complication of chronic kidney disease (CKD). Hungry bone syndrome (HBS) after parathyroidectomy (PTX) is a serious complication, which can lead to diarrhea, convulsion, arrhythmia and even death. This study was aimed to determine the risk factors for HBS after PTX in dialysis patients with SHPT and construct a nomogram prediction model to predict the incidence of postoperative complications. METHODS: Clinical data were collected from 80 maintenance hemodialysis (MHD) patients with SHPT who received total PTX in the Second Hospital of Jilin University from January 2018 to September 2021. In line with the inclusion and exclusion criteria, totally 75 patients were finally enrolled for analysis. Patients were divided into two groups for retrospective analysis according to the severity of postoperative HBS, including HBS group and non-HBS (N-HBS) group. Univariate and multivariate logistic regression analyses were conducted to determine the risk factors for postoperative HBS. Afterwards, the receiver operating characteristic (ROC) curves were plotted based on the statistical analysis results, aiming to compare the prediction effects of different predicting factors. Finally, the nomogram was established to evaluate the occurrence probability of postoperative complications predicted by the risk factors. RESULTS: Among the 75 patients, 32 had HBS (HBS group), while 43 did not have HBS (N-HBS group). Univariate analysis results indicated that, the preoperative intact parathyroid hormone (iPTH) and serum alkaline phosphatase (ALP) levels in HBS group were significantly higher than those in N-HBS group, while preoperative hemoglobin and preoperative albumin (Alb) levels were significantly lower than those in N-HBS group. As discovered by multivariate logistic regression analysis, preoperative iPTH (OR = 1.111, P = 0.029) and ALP (OR = 1.010, P < 0.001) were the independent risk factors for postoperative HBS. ROC curve analysis suggested that the area under the curve (AUC) values of these two indicators were 0.873 and 0.926, respectively (P < 0.0001). Subsequently, the nomogram model for predicting HBS was constructed. The model verification results indicated that the predicted values were basically consistent with the measured values, with the C-index of 0.943 (95% CI 0.892-0.994). Besides, the calibration curve was consistent with the ideal curve, demonstrating the favorable accuracy and discrimination of the model. CONCLUSIONS: Preoperative iPTH and preoperative ALP are the risk factors for postoperative HBS, which can be used to guide the early clinical intervention.

Transient binocular vision loss and pain insensitivity in Klippel-Feil syndrome: a case report.

BACKGROUND: Klippel-Feil syndrome is a rare congenital bone disorder characterized by an abnormal fusion of two or more cervical spine vertebrae. Individuals with Klippel-Feil syndrome exhibit diverse clinical manifestations, including skeletal irregularities, visual and hearing impairments, orofacial anomalies, and anomalies in various internal organs, such as the heart, kidneys, genitourinary system, and nervous system. CASE PRESENTATION: This case report describes a 12-year-old Pashtun female patient who presented with acute bilateral visual loss. The patient had Klippel-Feil syndrome, with the typical clinical triad symptoms of Klippel-Feil syndrome, along with Sprengel's deformity. She also exhibited generalized hypoalgesia, which had previously resulted in widespread burn-related injuries. Upon examination, bilateral optic disc swelling was observed, but intracranial pressure was found to be normal. Extensive investigations yielded normal results, except for hypocalcemia and low vitamin D levels, while parathyroid function remained within the normal range. Visual acuity improved following 2 months of calcium and vitamin D supplementation, suggesting that the visual loss and optic nerve swelling were attributed to hypocalcemia. Given the normal parathyroid function, it is possible that hypocalcemia resulted from low vitamin D levels, which can occur after severe burn scarring. Furthermore, the patient received a provisional diagnosis of congenital insensitivity to pain on the basis of the detailed medical history and the findings of severe and widespread loss of the ability to perceive painful stimuli, as well as impaired temperature sensation. However, due to limitations in genetic testing, confirmation of the congenital insensitivity to pain diagnosis could not be obtained. CONCLUSION: This case highlights a rare presentation of transient binocular vision loss and pain insensitivity in a patient with Klippel-Feil syndrome, emphasizing the importance of considering unusual associations in symptom interpretation.

[Association between preoperative cholecalciferol therapy and hypocalcemia after parathyroidectomy in patients with primary hyperparathyroidism].

BACKGROUND: Primary hyperparathyroidism (PHPT) is a endocrine disorder characterized by excessive secretion of parathyroid hormone (PTH) from parathyroid gland tumors. Parathyroidectomy (PTE) is the main treatment for PHPT, but it can lead to hypocalcemia in up to 46% of cases. Hypocalcemia is associated with seizures and life-threatening cardiac arrhythmias, and vitamin D deficiency can exacerbate PHPT severity and contribute to «hungry bones syndrome,¼ resulting in severe and persistent postoperative hypocalcemia. AIM: To evaluate the association and determine the strength of the relationship between preoperative cholecalciferol therapy and the occurrence of hypocalcemia within 1-3 days after PTE in patients with PHPT. MATERIALS AND METHODS: The study was conducted at the Endocrinology Research Centre, during the periods of 1993-2010 and 2017-2020. The inclusion criteria consisted of patients diagnosed with PHPT who required PTE, had a serum 25-hydroxyvitamin D (25(OH)D) level below 20 ng/mL, and a serum total calcium level below 3 mmol/L. The exclusion criterion was the use of medications that affect calcium-phosphorus metabolism, including cinacalcet, denosumab, or bisphosphonates, either as monotherapy or as part of combination therapy. RESULTS: There were 117 patients, including 110 (94%) females and 7 (6%) males. The median age and interquartile range were 58 [49; 65] years. Among the participants, 21 (18%) received cholecalciferol supplementation for a duration of 2 weeks to 2 months prior to PTE, aiming to address vitamin D deficiency. The remaining 96 (82%) participants did not receive -cholecalciferol supplementation. Both groups, i.e., participants receiving cholecalciferol and those who did not, were similar in terms of anthropometric factors (sex and age at the time of surgery), preoperative clinical characteristics (BMD decrease), and laboratory parameters (PTH, total calcium, phosphorus, ALP, OC, CTX-1, and 25(OH)D levels). The occurrence of postoperative hypocalcemia was significantly lower in participants who received cholecalciferol supplementation (10% vs. 63%, p<0,001, FET2). Cholecalciferol intake showed a negative association with hypocalcemia development (RR=0,15, 95% CI (0,03; 0,51)). CONCLUSION: Preoperative cholecalciferol supplementation for 2 weeks to 2 months before PTE reduces the risk of postoperative hypocalcemia in patients with PHPT by 2-33 times.

Recurrent severe hypocalcemia following chemotherapy regimen changes in advanced breast cancer: two case reports.

BACKGROUND: As an oncologic emergency related to abnormalities in calcium metabolism, hypercalcemia associated with paraneoplastic syndrome and bone metastases is well known. Meanwhile, the incidence of hypocalcemia is low, except in cases associated with bone-modifying agents used for bone metastases. Hypocalcemia induced by bone-modifying agents typically occurs early after the initial administration, and its incidence can be significantly reduced by preventive administration of calcium and vitamin D3 supplements. CASE REPORT: We report two cases of recurrent severe hypocalcemia occurring during chemotherapy for metastatic breast cancer with multiple bone metastases. Case 1: A 35-year-old Japanese woman developed metastases in the bone, liver, and ovaries during postoperative endocrine therapy for invasive lobular carcinoma of the breast. She underwent chemotherapy and treatment with denosumab. She experienced recurrent episodes of severe hypocalcemia subsequent to a change in the chemotherapy regimen. Case 2: A 65-year-old Japanese woman encountered multiple bone metastases after postoperative anti-human epidermal growth factor receptor 2 therapy and during endocrine therapy for invasive ductal carcinoma of the breast. She underwent anti-human epidermal growth factor receptor 2 therapy and treatment with denosumab. She experienced recurrent severe hypocalcemia subsequent to a change in the chemotherapy regimen to letrozole + lapatinib, trastuzumab emtansine, and lapatinib + capecitabine. CONCLUSIONS: We observed two cases of recurrent severe hypocalcemia in patients with advanced breast cancer and bone metastases after modifications to their therapy regimens. These cases differed from the typical hypocalcemia induced by bone-modifying agents. It is possible that antitumor drugs affect calcium and bone metabolism associated with bone metastases. While these cases are rare, it is crucial for oncologists to be aware of hypocalcemia not only at the initiation of bone-modifying agents but also throughout the entire antitumor therapy, as hypocalcemia can lead to fatal outcomes.

Denosumab-induced hypocalcemia in patients with solid tumors and renal dysfunction: a multicenter, retrospective, observational study.

BACKGROUND: Bone metastases are frequently observed in advanced cancer, and bone modifying agents are used to prevent or treat skeletal-related events. Zoledronic acid is contraindicated in patients with severe renal impairment (Ccr < 30 mL/min), but it is not completely known whether denosumab can be used in them. We aimed to determine the association between renal function and hypocalcemia development during denosumab treatment. METHODS: We included patients with solid cancer and bone metastases who started denosumab treatment between April 2017 and March 2019. They were classified into four groups based on creatinine clearance (Ccr; mL/min): normal (Ccr ≥ 80), mild (50 ≤ Ccr ˂80), moderate (30 ≤ Ccr ˂50), and severe (Ccr ˂30). Hypocalcemia was evaluated using the Common Terminology Criteria for Adverse Events (v5.0) based on the albumin-adjusted serum calcium levels; its incidence (stratified by renal function) and risk factors were investigated using a Chi-square test and logistic regression analysis. RESULTS: Of 524 patients (age: 69 ± 11 years; 303 men), 153 had a normal renal function and 222, 117, and 32 had mild, moderate, and severe renal dysfunction. The albumin-adjusted serum calcium level was higher than the measured (total) calcium level in most patients. The incidence of grade ≥ 1 hypocalcemia was 32.0% in the normal group and 37.4%, 29.9%, and 62.5% in the mild, moderate, and severe renal dysfunction groups, respectively. It was, therefore, higher in the severe renal dysfunction groups than in the normal group (P = 0.002). The incidence of grade ≥ 3 hypocalcemia did not differ significantly among the groups. Pre-treatment low serum calcium levels and severe renal dysfunction were risk factors for hypocalcemia. CONCLUSIONS: Evaluating denosumab-induced hypocalcemia required albumin adjustment, and its incidence was high among patients with severe renal dysfunction. Reduced serum calcium levels and severely impaired renal function were associated with an elevated hypocalcemia risk.

Neonatal hypocalcaemic seizures unmasking asymptomatic maternal primary hyperparathyroidism.

Hypocalcaemia is a common cause of neonatal seizures. Here, we present a breastfed neonate with smooth perinatal transition and no family history of seizures presenting at 3 weeks with recurrent multifocal clonic seizures. On evaluation, the neonate was found to have low iCa and total calcium. 25-hydroxy vitamin D (25(OH)D) level was low and intact parathyroid hormone (iPTH) was inappropriately normal. The maternal evaluation revealed high calcium and low phosphate levels. iPTH was very high and 25(OH)D was very low in the mother. Sestamibi scan showed a left inferior parathyroid adenoma in the mother. Maternal primary hyperparathyroidism causing hypercalcaemia can suppress parathyroid activity in the fetus, resulting in inappropriate parathyroid response to hypocalcaemia after birth causing recurrent hypocalcaemic seizures. So neonatal hypocalcaemic seizures need careful evaluation of the neonate and the mother at times and can help both mother and neonate.

A Rare Reason for Severe Hypocalcemia Following Kidney Transplant: Denosumab Treatment.

Deviations of calcium, phosphate, parathyroid hormone, and vitamin D levels are the basis for the diagnosis of calcium-phosphate metabolism disorders. The plasma concentration of the biologically active form known as free calcium is regulated in a harmonious manner by its exchange in the bones and reabsorption by the kidneys. These steps take place under the control of parathyroid hormone and calcitriol. In the process of chronic kidney disease, the kidney cannot synthesize adequate calcitriol, and the resulting hypocalcemia and hyperphosphatemia cause the development of secondary hyperparathyroidism. Osteoporosis is a metabolic bone disease and is essentially the consequence of osteoclastogenesis-induced bone resorption that exceeds bone formation. Osteoporosis is common after kidney transplant. However, hypocalcemia following kidney transplant is rare. The hungry bone syndrome after parathyroidectomy is often responsible for this condition in the pretransplant period. Denosumab is a human monoclonal antibody developed against the receptor activator of nuclear factor kappa-B ligand (known as RANKL). Denosumab exerts an antiresorptive effect on bones by reducing differentiation into osteoclasts. It is an effective treatment option for osteoporosis in the general population. There is insufficient scientific data regarding the use of denosumab in kidney transplant patients. Here, we present the case of a kidney transplant recipient who developed severe hypocalcemia (serum calcium 4.7 mg/dL) after denosumab treatment for osteoporosis.

Risk factors for postoperative hypocalcemia following total thyroidectomy: a retrospective study.

BACKGROUND: and Objectives: Hypocalcemia is a commonly reported complication after thyroid surgery. Many possible risk factors have been identified. The purpose of this study is to analyze various risk factors possibly associated with development of postoperative hypocalcemia after thyroid surgery by dividing the sample population into postoperative hypocalcemia and normal calcium groups. DESIGN: Retrospective. SETTING: Multiple centers in the Makkah region of Saudi Arabia. PATIENTS AND METHODS: Risk factors for postoperative hypocalcemia that were obtained for analysis include patient factors, perioperative blood parameters factors, disease-related factors, and surgical factors. Postoperative hypocalcemia was defined as a reduction of the total calcium level to <8.0 mg/dL. Hypocalcemic and normocalcemic patients were compared by multivariate logistic regression. MAIN OUTCOME MEASURES: Distinguish independent risk factors for postoperative hypocalcemia after thyroidectomy. SAMPLE SIZE: 215 patients. RESULTS: The incidence of hypocalcemia was 52.1% (112 of 215 patients). According to multivariate analysis, statistically significant risk factors for predicting postoperative hypocalcemia included postoperative parathyroid hormone level <10 pg/dL, inadvertent parathyroid gland resection, and neck dissection surgeries. CONCLUSION: The causes of postoperative hypocalcemia are multi-factorial. Because many of these factors are modifiable, they should be identified postoperatively to distinguish high-risk groups and implement early preventive measures. LIMITATIONS: Retrospective with a relatively small size. We encourage additional prospective studies with a larger sample size in multiple regions of the country, which might reveal further significant results.

Renal diseases that course with hypomagnesemia. Comments on a new hereditary hypomagnesemic tubulopathy.

Renal diseases associated with hypomagnesemia are a complex and diverse group of tubulopathies caused by mutations in genes encoding proteins that are expressed in the thick ascending limb of the loop of Henle and in the distal convoluted tubule. In this paper, we review the initial description, the clinical expressiveness and etiology of four of the first hypomagnesemic tubulopathies described: type 3 Bartter and Gitelman diseases, Autosomal recessive hypomagnesemia with secondary hypocalcemia and Familial hypomagnesemia with hypercalciuria and nephrocalcinosis. The basic biochemical patterns observed in renal tubular hypomagnesemias and the modalities of transport and interaction that occur between the transporters involved in the reabsorption of magnesium in the distal convoluted tubule are described below. Finally, the recent report of a new renal disease with hypomagnesemia, type 2 hypomagnesemia with secondary hypocalcemia caused by reduced TRPM7 channel activity is described.

Azathioprine and hydroxychloroquine overdose in Sjögren's syndrome patient with hypocalcemia: a case report.

INTRODUCTION: Hydroxychloroquine and azathioprine have been routinely used to control and treat primary and secondary Sjögren's syndrome, which potentially triggered some overdoses by these drugs. Toxicity from hydroxychloroquine and azathioprine manifests in the form of cardiac conduction abnormalities, nausea, vomiting, and muscle weakness. Recognizing these unique drug overdoses and management of these toxicities is important. This case report aims to expand our current understanding of these drug overdoses and their management and also underscores the importance of anticipating and identifying fewer common complications, such as hypocalcemia. CASE REPORT: A 34-year-old Persian woman with a history of Sjögren's syndrome presented to the emergency department 3.5-4 hours after an intentional overdose of hydroxychloroquine and azathioprine and severe hypotension and loss of consciousness. Although the patient was regularly taking other medications, such as fluoxetine, naproxen, and prednisolone, she explicitly clarified that these were not the substances involved in her overdose. Early investigations showed hypokalemia (2.4 mEq/L), hypocalcemia (7.5 mg/dL), and hypoglycemia (65 mg/dL). She was also diagnosed with metabolic acidosis and respiratory alkalosis. The electrocardiogram showed changes in favor of hypokalemia; other lab tests were run on the patient. Supportive treatments were applied, including rapid intravenous fluid dextrose 5%, normal saline, potassium chloride 30 mEq, and calcium gluconate 100 mg. The patient was managed and monitored overnight in the emergency room and recovered without residual side effects. CONCLUSION: Hydroxychloroquine and azathioprine toxicity are considered rare, but it is likely to increase in frequency given the prevalence and increase in autoimmune diseases and the increasing usage of these drugs in treating such diseases. We found hypocalcemia as the presentation to this patient, which needs further investigation into the probable mechanism. Clinicians need to consider the unique effects of hydroxychloroquine and azathioprine poisoning and initiate appropriate emergency interventions to improve the outcomes in similar patients.