Serum parathyroid hormone and alkaline phosphatase as predictors of calcium requirements after total parathyroidectomy for hypocalcemia in secondary hyperparathyroidism

Identification of novel risk factors for postoperative severe hypocalcemia in patients with primary hyperparathyroidism undergoing parathyroidectomy: a case control study

BACKGROUND

Patients with primary hyperparathyroidism (PHPT) are at risk for severe hypocalcemia (SH) following parathyroidectomy (PTX), but limited data exist on the predictors of SH. We aimed to identify risk factors for early postoperative SH after PTX in patients with PHPT and to evaluate the predictive value of clinical parameters.

METHODS

A retrospective review of patients with PHPT who underwent PTX between January 2010 and December 2022 was performed. A total of 46 patients were included in the study, with 15 (32.6%) experiencing postoperative SH, 19 (41.3%) having calculi in the ureter or kidney, and 37 (80.4%) having osteoporosis. Patients were divided into SH and non-SH groups based on postoperative serum calcium levels. Preoperative biochemical indicators, bone turnover markers, and renal function parameters were analyzed and correlated with postoperative SH.

RESULTS

Statistically significant (P < 0.05) differences were found in preoperative serum calcium (serum Ca), intact parathyroid hormone, serum phosphorus (serum P), serum Ca/P, percentage decrease of serum Ca, total procollagen type 1 intact N-terminal propeptide, osteocalcin (OC), and alkaline phosphatase levels between the two groups. Multivariate analysis showed that serum P (odds ratio [OR] = 0.989; 95% confidence interval [95% CI] = 0.981-0.996; P = 0.003), serum Ca (OR = 0.007; 95% CI = 0.001-0.415; P = 0.017), serum Ca/P (OR = 0.135; 95% CI = 0.019-0.947; P = 0.044) and OC levels (OR = 1.012; 95% CI = 1.001-1.024; P = 0.036) were predictors of early postoperative SH. The receiver operating characteristic curve analysis revealed that serum P (area under the curve [AUC] = 0.859, P < 0.001), serum Ca/P (AUC = 0.735, P = 0.010) and OC (AUC = 0.729, P = 0.013) had high sensitivity and specificity.

CONCLUSION

Preoperative serum P, serum Ca/P and osteocalcin levels may identify patients with PHPT at risk for early postoperative SH after PTX.

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.

Brown Tumour in Chronic Kidney Disease: Revisiting an Old Disease with a New Perspective

Osteitis fibrosa cystica (OFC) and Brown Tumours are two related but distinct types of bone lesions that result from the overactivity of osteoclasts and are most often associated with chronic kidney disease (CKD). Despite their potential consequences, these conditions are poorly understood because of their rare prevalence and variability in their clinical manifestation. Canonically, OFC and Brown Tumours are caused by secondary hyperparathyroidism in CKD. Recent literature showed that multiple factors, such as hyperactivation of the renin-angiotensin-aldosterone system and chronic inflammation, may also contribute to the occurrence of these diseases through osteoclast activation. Moreover, hotspot KRAS mutations were identified in these lesions, placing them in the spectrum of RAS-MAPK-driven neoplasms, which were until recently thought to be reactive lesions. Some risk factors contributed to the occurrence of OFC and Brown Tumours, such as age, gender, comorbidities, and certain medications. The diagnosis of OFC and Brown Tumours includes clinical symptoms involving chronic bone pain and laboratory findings of hyperparathyroidism. In radiological imaging, the X-ray and Computed tomography (CT) scan could show lytic or multi-lobular cystic alterations. Histologically, both lesions are characterized by clustered osteoclasts in a fibrotic hemorrhagic background. Based on the latest understanding of the mechanism of OFC, this review elaborates on the manifestation, diagnosis, and available therapies that can be leveraged to prevent the occurrence of OFC and Brown Tumours.

A New Calculation Model for Calcium Requirements After Parathyroidectomy in Patients With Secondary Hyperparathyroidism

OBJECTIVES

We aimed to develop a new calculation model for calcium requirements in dialysis patients following parathyroidectomy.

METHODS

A total of 98 patients with secondary hyperparathyroidism receiving parathyroidectomy from January 2014 to January 2022 were enrolled in this study. Among these patients, 78 were randomly selected for construction of the calcium requirement calculation model, and the remaining 20 patients were selected for model validation. The calcium requirement model estimated the total calcium supplementation for 1 week after surgery using variables with significant relationships in the derivation group by stepwise multiple linear regression analysis. Bias, precision, and accuracy were measured in the validation group to determine the performance of the model.

RESULTS

The model was as follows: calcium requirement for 1 week after surgery=33.798-8.929×immediate postoperative calcium+0.190×C-reactive protein-0.125×age+0.002×preoperative intact parathyroid hormone+0.003×preoperative alkaline phosphatase (R2=0.8). The model was successfully validated.

CONCLUSION

We generated a novel model to guide calcium supplementation. This model can assist in stabilizing the serum calcium levels of patients during the early postoperative period. Furthermore, it contributes to the individualized and precise treatment of hypocalcemia in patients following parathyroidectomy.

Alkaline Phosphatases: Biochemistry, Functions, and Measurement

Alkaline phosphatases (ALPs) are a group of isoenzymes, situated on the external layer of the cell membrane; they catalyze the hydrolysis of organic phosphate esters present in the extracellular space. Zinc and magnesium are significant co-factors for the biological activity of these enzymes. Although ALPs are available in various body tissues and have distinct physiochemical properties, they are true isoenzymes since they catalyze a similar reaction. In the liver, ALP is cytosolic and present in the canalicular membrane of the hepatocytes. ALPs are available in placenta, ileal mucosa, kidney, bone, and liver. However, most of the ALPs in serum (over 80%) are delivered from liver and bone and in more modest quantities from the intestines. Despite the fact that alkaline phosphatases are found in numerous tissues all through the body, their exact physiological function remains largely unknown.

Risk Factor Analysis and Prediction of Severe Hypocalcemia after Total Parathyroidectomy without Auto-Transplantation in Patients with Secondary Hyperparathyroidism

OBJECTIVE

Our study aimed to develop and validate a nomogram to predict severe hypocalcemia (SH) before total parathyroidectomy (TPTX) without auto-transplantation in patients with secondary hyperparathyroidism.

METHODS

A total of 299 consecutive patients who underwent TPTX without transplantation for secondary hyperparathyroidism were selected from the General Hospital of Northern Theater Command between January 2013 and December 2021. Of these, patients who underwent surgery between January 2013 and December 2020 formed the training cohort (n = 208) to develop a nomogram, and those who underwent surgery thereafter formed the validation cohort (n = 91) to validate the performance of this nomogram. Univariate and multivariate logistic regression analyses were used to identify the risk factors associated with SH, and then, a nomogram was constructed.

RESULTS

The incidence of postoperative SH was 27.9% and 35.2% in the training and validation cohorts, respectively. The preoperative factors associated with SH were younger age, lower serum calcium (Ca) level, higher intact parathyroid hormone (iPTH) level, and higher serum alkaline phosphatase (ALP) level. Incorporating these 4 factors, the nomogram achieved good concordance indexes of 0.866 (95%CI, 0.816-0.916) and 0.867 (95% CI, 0.793-0.941) in predicting SH in the training and validation cohorts, respectively, and had well-fitted calibration curves. The positive predictive values of the nomogram were 64.7% (54.1%-78.4%) and 75.0% (58.6%-88.5%), and negative predictive values of the nomogram were 90.0% (82.9%-93.6%) and 86.4% (73.5%-94.0%) for the training and validation cohorts, respectively.

CONCLUSIONS

We developed and validated a nomogram for the prediction of SH in patients who underwent TPTX without auto-transplantation for secondary hyperparathyroidism. Our nomogram may facilitate the identification of high-risk SH in patients after TPTX and optimization of preoperative decision-making.

A reappraisal of risk factors for early hypocalcemia after parathyroidectomy in dialysis patients

We aimed to identify risk factors for early hypocalcemia after parathyroidectomy in patients with secondary hyperparathyroidism. We retrospectively enrolled 106 of 120 consecutive patients with secondary hyperparathyroidism who underwent parathyroidectomy between January 2019 and July 2021. Perioperative laboratory parameters, preoperative computerized tomography (CT) images, and postoperative histology were evaluated. Parathyroid calcification was defined as hyperdense regions with a density of > 130 Hounsfield Units on CT images of the parathyroid. Subtotal parathyroidectomy, total parathyroidectomy without auto-transplantation, or total parathyroidectomy with auto-transplantation were performed in the present study. Postoperative hypocalcemia was defined as a serum calcium concentration < 2.1 mmol/L within 4 days of surgery. The participants were categorized according to the presence (n = 33) or absence (n = 73) of postoperative hypocalcemia. The demographics, comorbidities, and surgical details were similar in the two groups. Multivariate analysis showed that the preoperative alkaline phosphatase activity, serum intact parathyroid hormone and calcium concentrations, and parathyroid calcification were independent risk factors for postoperative hypocalcemia (all P < 0.05). Receiver operating characteristic analysis generated areas under the curves for preoperative alkaline phosphatase, intact parathyroid hormone, and parathyroid calcification of 0.82, 0.80, and 0.70, respectively (all P < 0.05). Cut-off values for preoperative alkaline phosphatase (> 242.9 IU/L) and intact parathyroid hormone (> 2,104 pg/mL) were found to be predictive of postoperative hypocalcemia. High preoperative alkaline phosphatase activity and serum intact parathyroid hormone concentration and low serum calcium are associated with higher risks of postoperative hypocalcemia. Calcification of the parathyroid may represent a novel radiologic means of predicting postoperative hypocalcemia.

Risk Factors for Severe Hypocalcemia in Patients with Secondary Hyperparathyroidism after Total Parathyroidectomy

BACKGROUND

Hypocalcemia is the most common complication of total parathyroidectomy in secondary hyperparathyroidism (SHPT) and is associated with adverse consequences such as spasms, epilepsy, and arrhythmia and even death if the serum calcium level decreases rapidly. Previous studies have identified several risk factors for postoperative severe hypocalcemia (SH) in patients with SHPT, but the sample sizes were small and thus the results may not be reliable.

OBJECTIVES

This study was performed to investigate the risk factors for SH after total parathyroidectomy without autotransplantation (tPTX) in a large sample of patients with uremic hyperparathyroidism.

METHODS

We retrospectively investigated the records of 1,095 patients with SHPT treated with tPTX between January 2008 and December 2018. Based on the postoperative serum calcium concentration, the patients were grouped into SH and non-SH groups. The clinical characteristics and biochemical results were analyzed, and binary logistic regression analysis was used to identify the risk factors for SH.

RESULTS

After surgery, 25.9% of the patients developed SH. Age, diastolic blood pressure (DBP), heart rate, frequency of bone pain, weight of resected glands, preoperative serum calcium, intact parathyroid hormone (iPTH), alkaline phosphatase (ALP), and hemoglobin levels differed between the two groups. Binary logistic regression analyses identified preoperative serum calcium, iPTH, and ALP levels as independent predictors of SH after surgery.

CONCLUSIONS

The preoperative serum calcium, iPTH, and ALP levels can be used to assess the risk of postoperative SH in patients with SHPT. Such patients should thus be monitored closely in order to initiate prompt interventions to avoid SH.

Hungry bone syndrome after parathyroidectomy in end-stage renal disease patients: review of an alkaline phosphatase-based treatment protocol

AIM

Hyperparathyroidism in chronic kidney disease-mineral and bone disorder is associated with significant morbidity and mortality. Parathyroidectomy is widely carried out as treatment despite complications such as hypocalcaemia post-surgery. Our centre has been using an ALP-based protocol to replace calcium postoperatively to prevent hypocalcaemia. We aim to describe and audit our calcium replacement protocol post-parathyroidectomy METHODS: We, retrospectively, analyse 167 end-stage kidney disease patients who had parathyroidectomy with auto-implantation in Singapore General Hospital between January 2008 and December 2013. Their calcium replacement postoperatively was initiated upon patient arrival back in ward on the same day of surgery based on their pre-op ALP prior to occurrence of hypocalcaemia. Patient demographics, surgical and laboratory parameters were reviewed from medical records. Changes in calcium postoperatively were reported to look for incidence of calcium derangement.

RESULTS

Mean calcium levels between pre-operation day and post-operation day 7 ranged from 2.31 to 2.70 mmol/L. Decline in serum calcium was common in all patients prior to starting calcium replacement. Eighteen patients (10.9%) experienced hypocalcaemia immediately post-operation prior to commencement of IV calcium replacement. Patients with immediate post-operation hypocalcaemia had lower pre-operation calcium but higher pre-operation alkaline phosphatase (ALP) and pre-operation intact parathyroid hormone. Hypercalcaemia is common likely from aggressive IV calcium replacement using the protocol. The average length of stay for patients prior to calcium stabilization and discharge was 9 days.

CONCLUSION

Implementation of an ALP-based prophylactic calcium replacement protocol with daily serum calcium monitoring can ameliorate severe hypocalcaemia post-parathyroidectomy.

Postsurgical Evaluation of Secondary Nephrogenic Hyperparathyroidism

Parathyroidectomy is useful for the treatment of secondary hyperparathyroidism (SHPT) caused by chronic renal failure. The following three types of parathyroidectomy can be performed: subtotal parathyroidectomy, total parathyroidectomy and total parathyroidectomy plus autologous transplantation (tPTX+AT). Each of the three types of surgery has advantages and disadvantages. The present study retrospectively analyzed the efficacy of tPTX+AT for the treatment of SHPT over 1 year. Thirty-seven patients who were diagnosed with secondary nephrogenic hyperparathyroidism and treated with tPTX+AT were selected between September 2014 and October 2016 and followed up for 1 year. Their average age was 66.5±46.0 years, and the average time of dialysis was 48.1±8.2 months. The patients' conditions, including the levels of intact parathyroid hormone (iPTH) and bone metabolism, were compared preoperatively and 1 and 7 days and 1, 3, 6 and 12 months after surgery. In addition, the postoperative complications, pathological data, SHPT recurrence and prognosis were examined. The results showed that the postoperative level of ostalgia and cutaneous pruritus significantly decreased in the patients. An inspection of the parathyroid tissues during the operation confirmed the presence of parathyroid gland hyperplasia with no carcinoma detected. Three patients with hoarseness recovered within 1 month, and 1 patient with unilateral recurrent laryngeal nerve injury improved after 6 months of voice training. Compared to the preoperative condition, the postoperative serum iPTH, serum calcium and serum phosphate levels were significantly decreased (P<0.001), and these differences remained significant 12 months after surgery. Compared to the preoperative condition, the alkaline phosphatase (ALP) concentration was decreased on postoperative day 1 (P<0.05), but no differences were observed on day 7 or at 1 month (P>0.05). The ALP levels continuously decreased at 3, 6 and 12 months (P<0.01). In conclusion, tPTX+AT significantly improves the quality of life and serum biomarker levels of these patients. The convenient surgical removal of the hyperplastic parathyroid gland for postoperative recurrence supports tPTX+AT as the recommended treatment for relevant patients.