Clinical features and hyperplastic patterns of parathyroid glands in hemodialysis patients with advanced secondary hyperparathyroidism refractory to maxacalcitol treatment and required parathyroidectomy

Relationship between intraoperative measured parameters of parathyroid gland and pathological patterns in patients with secondary hyperparathyroidism

Background

The hyperplastic patterns of parathyroid glands (PTGs) in secondary hyperparathyroidism (SHPT) are critical for surgical indication and deciding on the approach. Earlier histopathological investigations have suggested the occurrence of an initial increase in the parathyroid cells, with a normal lobular structure (diffuse hyperplasia, DH). After this, the PTGs become hyperplastic with some nodules (nodular hyperplasia, NH). The current study aimed to explore the relationship between the intraoperative measurements of weight, volume, and maximal diameter of dissected PTGs and the histopathological diagnosis of SHPT patients with end-stage renal disease.

Methods

A total of 182 SHPT patients who received parathyroidectomy (PTX) were retrospectively enrolled. Altogether 21 patients were selected as having at least one diffuse polyclonal hyperplasia PTG. Intraoperative measurements of weight, volume, and maximal diameter of dissected PTGs were compared between tissues with DH and NH.

Results

Intraoperative dissected PTGs were verified histologically. The differences in the intraoperative measurements of weight, volume, maximal diameter, and the combination of the three measurements between the DH and the NH PTGs groups were significant (P=0.000), and the values of area under the ROC curve (AUCs) were 0.824 (95% CI: 0.731–0.918), 0.812 (95% CI: 0.716–0.908), 0.746 (95% CI: 0.633–0.860), and 0.851 (95% CI: 0.768–0.935), respectively, with cut-off values of the three parameters being 0.19 g, 206.3 mm³, and 10.5 mm, respectively.

Conclusions

The measurement of weight, volume, and maximal diameter of dissected PTGs is a possible alternative to assess the hyperplasia patterns of the dissected PTGs. It is a promising reference for the ultrasound prediction of pathological patterns of PTGs.

Calcium-mediated parathyroid hormone suppression test in uraemic secondary hyperparathyroidism

AIM

The present study aimed to investigate the value of calcium-mediated parathyroid hormone (PTH) suppression test in evaluating the autonomic secretory function of parathyroid, and the management of uraemic secondary hyperparathyroidism (SHPT).

METHODS

Calcium-mediated PTH suppression test was performed in dialysis with SHPT, who were candidates for parathyroidectomy from June 2017 to December 2019 in our hospital. The PTH inhibition rate (PTH-IR) was calculated, and the correlation between PTH-IR and clinical indicators was explored.

RESULTS

Fifty-one subjects were included. PTH-IR was negatively correlated with baseline PTH (r = -0.35, P = .012), it was also correlated with dialysis years, coronary artery calcification score (CACS) and parathyroid mass (r = -0.397, P = .004; r = -0.327, P = .028; r = -0.363, P = .015), which were not found for baseline PTH. Forty-four patients underwent surgical treatment. According to the histological results, 26 patients presented with parathyroid non-nodular hyperplasia, and 18 patients presented with parathyroid nodular hyperplasia. The mass of parathyroid of patients with nodular hyperplasia was higher than that of patients with non-nodular hyperplasia (ρ = 0.01). The difference of the PTH-IR was not found between the two groups (ρ = 0.296). During the test, the highest serum calcium was 2.9 ± 0.4 mmol/L, which dropped to normal at the end of the test.

CONCLUSION

Parathyroid hormone inhibition rate might be a useful indicator in evaluating the autonomic secretory function of parathyroid and the progression of SHPT on top of intact PTH. Calcium-mediated PTH suppression test was safe in uraemic SHPT patients, but need to monitor for transient hypercalcaemia.

The Emerging Role of Nutritional Vitamin D in Secondary Hyperparathyroidism in CKD

In chronic kidney disease (CKD), hyperphosphatemia induces fibroblast growth factor-23 (FGF-23) expression that disturbs renal 1,25-dihydroxy vitamin D (1,25D) synthesis; thereby increasing parathyroid hormone (PTH) production. FGF-23 acts on the parathyroid gland (PTG) to increase 1α-hydroxylase activity and results in increase intra-gland 1,25D production that attenuates PTH secretion efficiently if sufficient 25D are available. Interesting, calcimimetics can further increase PTG 1α-hydroxylase activity that emphasizes the demand for nutritional vitamin D (NVD) under high PTH status. In addition, the changes in hydroxylase enzyme activity highlight the greater parathyroid 25-hydroxyvitmain D (25D) requirement in secondary hyperparathyroidism (SHPT); the higher proportion of oxyphil cells as hyperplastic parathyroid progression; lower cytosolic vitamin D binding protein (DBP) content in the oxyphil cell; and calcitriol promote vitamin D degradation are all possible reasons supports nutritional vitamin D (NVD; e.g., Cholecalciferol) supplement is crucial in SHPT. Clinically, NVD can effectively restore serum 25D concentration and prevent the further increase in PTH level. Therefore, NVD might have the benefit of alleviating the development of SHPT in early CKD and further lowering PTH in moderate to severe SHPT in dialysis patients.

Vitamin D Receptor Activators

The fields for clinical employment of vitamin D analogs are growing and under active evaluation in different medical specialties, ranging from dermatology to immunology and oncology. In this review we provide a brief description of the drugs that have been developed more specifically for the treatment of secondary hyperparathyroidism (SH) associated with uremia.

Risk-factors for nodular hyperplasia of parathyroid glands in sHPT patients

Introduction

Nodular hyperplasia of parathyroid glands (PG) is the most probable cause of medical treatment failure in secondary hyperparathyroidism (sHPT). This prospective cohort study is located at the interface of medical and surgical consideration of sHPT treatment options and identifies risk-factors for nodular hyperplasia of PG.

Material and methods

One-hundred-eight resected PG of 27 patients with a broad spectrum of sHPT severity were classified according to the degree of hyperplasia by histopathology. Twenty routinely gathered parameters from medical history, ultrasound findings of PG and laboratory results were analyzed for their influence on nodular hyperplasia of PG by risk-adjusted multivariable binary regression. A prognostic model for non-invasive assessment of PG was developed and used to weight the individual impact of identified risk-factors on the probability of nodular hyperplasia of single PG.

Results

Independent risk-factors for nodular hyperplasia of single PG were duration of dialysis in years, PG volume in mm³ determined by ultrasound and serum level of parathyroid hormone in pg/mL. Multivariable analyses computed a model with an Area Under the Receiver Operative Curve of 0.857 (95%-CI:0.773–0.941) when predicting nodular hyperplasia of PG. Theoretical assessment of risk-factor interaction revealed that the duration of dialysis had the strongest influence on the probability of nodular hyperplasia of single PG.

Conclusions

The three identified risk-factors (duration of dialysis, PG volume determined by ultrasound and serum level of parathyroid hormone) can be easily gathered in daily routine and could be used to non-invasively assess the probability of nodular hyperplasia of PG. This assessment would benefit from periodically collected data sets of PG changes during the course of sHPT, so that the choice of medical or surgical sHPT treatment could be adjusted more to the naturally changing type of histological PG lesion on an individually adopted basis in the future.

Ultrasound-based scores as predictors for nodular hyperplasia in patients with secondary hyperparathyroidism: a prospective validation study

PURPOSE

Former studies evaluated echostructural and vascular patterns in ultrasound of the parathyroid gland to identify nodular hyperplasia in patients with secondary hyperparathyroidism due to chronic kidney disease. This prospective study aims to externally validate suggested ultrasound classifications.

METHODS

Parathyroid glands of 27 patients with secondary hyperparathyroidism undergoing parathyroidectomy were prospectively analyzed. Ultrasound including Doppler imaging was performed 1 day prior to surgery. Ultrasound data were available for 70 parathyroid glands. Echostructural and vascular scores according to previous studies were applied calculating the area under the receiver operating characteristic curve (AUROC). Overall correctness, sensitivity, and specificity of the investigated scores were assessed with the Youden index method.

RESULTS

The Doppler score introduced by Vulpio and colleagues based on characteristic blood flow patterns in parathyroid glands showed an AUROC of 0.749 for the prediction of nodular hyperplasia with an overall correctness of 72.8%. Other ultrasound classifications based on blood flow patterns, as well as echostructure of the parathyroid gland displayed AUROCs of <0.700, thus, lacking sufficient capability as a prognostic model. Overall correctness of prediction varied from 53.8 to 55.9%.

CONCLUSIONS

The Vulpio Doppler score for the prediction of nodular hyperplasia in patients with secondary hyperparathyroidism was externally validated for the first time. Other ultrasound scores fail as prognostic models in this study population. Doppler sonography of the parathyroid gland has prognostic capability to identify nodular hyperplasia as surrogate marker for patients with secondary hyperparathyroidism indicating the need for ablative or surgical treatment when failing conservative therapy.

Parathyroid Ultrasonography in Renal Secondary Hyperparathyroidism: An Overlooked and Useful Procedure

In secondary hyperparathyroidism (SHPT), ultrasonography (US) can accurately define the size and structure of parathyroid glands as well as differentiate diffuse and nodular hyperplasia. US may be also useful to predict the response of SHPT to vitamin D analogs and cinacalcet and to assess for regression of parathyroid glands hyperplasia by measurement of parathyroid gland volume. There is increasing evidence that US can potentially identify patients who will benefit from prompt surgical intervention. Therefore, US should be part of the diagnostic armamentarium in the treatment of SHPT in the daily clinical practice.

Clinical significance of parathyroid intervention on CKD-MBD management

Recently published ‘Guidelines for the management of secondary hyperparathyroidism in chronic dialysis patients’ by the Japanese Society for Dialysis Therapy advocate that percutaneous ethanol injection into enlarged glands, which has been considered as the only alternative to parathyroidectomy (PTx), should be indicated in patients with a single enlarged parathyroid gland (estimated volume >500 mm³, or estimated major axis >10 mm), and that PTx should be recommended in patients with multiple enlarged glands. Cinacalcet cannot achieve optimal control of chronic kidney disease–mineral bone disorder in all patients, and parathyroid intervention will be required in a considerable number of patients with refractory secondary hyperparathyroidism.

Parathyroidectomy improves cardiovascular outcome in nondiabetic dialysis patients with secondary hyperparathyroidism

OBJECTIVE

Secondary hyperparathyroidism and its associated abnormalities in mineral metabolism and haemodynamic changes increase the cardiovascular risk in patients with end-stage renal disease (ESRD). Our objective was to determine the association of parathyroidectomy (PTX) with major cardiovascular events in nondiabetic dialysis patients with severe secondary hyperparathyroidism (SHPTH).

DESIGN AND PATIENTS

We performed a cohort study with fifty-three nondiabetic ESRD patients who were treated with maintenance haemodialysis and who had intact parathyroid hormone (PTH) levels > 800 pg/ml. Participants received either only medical therapy or medical therapy and total PTX with autotransplantation for SHPTH.

MEASUREMENTS

We evaluated the associations between PTX and major cardiovascular events including death, cerebrovascular accident and myocardial infarction. The biochemical and haemodynamic changes associated with PTX were measured.

RESULTS

During the mean follow-up of 72 months, twenty-three patients received only medical treatment (medical group) while thirty patients underwent PTX in addition to medical treatment (PTX group). The two groups were comparable in respect of baseline characteristics. PTX group was found to be associated with a reduced incidence of major cardiovascular events (P = 0·021). A multiple Cox regression analysis showed that the variable significantly associated with major cardiovascular events was treatment modality (medical therapy vs medical therapy and parathyroidectomy, hazard ratio = 26·12, 95% CI = 1·30-526·27, P = 0·033). Blood pressure, haemoglobin, alkaline phosphatase, calcium, phosphate and calcium × phosphate product significantly improved after PTX.

CONCLUSIONS

PTX was associated with better cardiovascular outcome in nondiabetic dialysis patients with severe SHPTH.

Presence of small parathyroid glands in renal transplant patients supports less-than-total parathyroidectomy to treat hypercalcemic hyperparathyroidism

BACKGROUND

Parathyroid glands (PG) are rarely analyzed in renal transplant (RTX) patients. This study analyzes comparatively PG of RTX and end-stage renal disease (ESRD) patients. The clinical part of the study evaluates if total parathyroidectomy with autotransplantation (TPT+AT) treats appropriately hypercalcemic hyperparathyroidism in RTX patients.

METHODS

TPT+AT was performed in 15 of 23 RTX and 21 of 27 ESRD patients. Remaining patients underwent less-than-total PT. Volume and stage of hyperplasia were determined from 86 PG of RTX and 109 PG of ESRD patients. Patients were categorized according to the presence of small PG (volume < 100 mm(3)). Calcium homeostasis and hyperparathyroidism were evaluated 2 years after PT in RTX patients.

RESULTS

PG of RTX patients were significantly smaller, but similar hyperplastic in comparison to PG of ESRD patients. Small PG were more frequent in RTX than in ESRD patients (19% vs 6%) and mainly graded normal or diffuse hyperplastic (94%). Forty-seven percent of RTX, but only 14% of ESRD, patients receiving a total PT possessed ≥1 small PG (P < .05). Overall, PT treated successfully hypercalcemic hyperparathyroidism. However, TPT+AT caused permanent hypocalcemia in 50% of RTX patients without small PG and even in 83% of RTX patients with small PG. All RTX patients receiving less-than-total PT were normocalcemic at 2-year follow-up. Logistic regression revealed a 10.7 times greater risk of permanent hypocalcemia in RTX patients with small PG receiving TPT+AT compared with RTX patients without small PG receiving TPT+AT or RTX patients undergoing less-than-total PT.

CONCLUSION

Surgeons performing PT should be aware of the high frequency of small and less diseased PG in RTX patients. In this context, TPT+AT might overtreat hypercalcemic hyperparathyroidism in RTX patients, especially when small PG are present.

Use of ultrasound to assess the response to therapy for secondary hyperparathyroidism

Secondary hyperparathyroidism (SHPT) is a common complication in patients with chronic kidney disease. In SHPT, the biology of parathyroid cells changes significantly toward diffuse nodular hyperplasia. Currently, diagnosis of SHPT is based on intact parathyroid hormone serum levels and parameters of mineral metabolism. The morphologic diagnosis of SHPT relies on high-resolution ultrasonography with color Doppler imaging. This report describes a maintenance hemodialysis patient with severe SHPT treated using conventional therapy (phosphate binders and oral/intravenous vitamin D or analogues) and the subsequent addition of a calcimimetic. The role of color Doppler ultrasonography in the diagnosis, clinical follow-up, and assessment of therapeutic response of SHPT is discussed. This case suggests that the availability of calcimimetics has changed the natural history of clinical SHPT and may change the therapeutic utility of parathyroidectomy. Use of color Doppler ultrasonography further supports these therapeutic advances, allowing evaluation of the morphologic and vascular changes in hyperplastic parathyroid glands and aiding clinical, pharmacologic, and surgical strategies.

Proliferating potential and apoptosis in the development of secondary hyperparathyroidism: a study based on Ki-67 immunohistochemical staining and the terminal dUTP nick-end labeling assay

Secondary hyperparathyroidism (SHPT) is a common complication in hemodialysis (HD) patients. SHPT progresses from initial diffuse hyperplasia (diffuse) to early nodularity (early), then to multinodular hyperplasia (nodular), and finally to a single nodule (single) consisting of uniform parenchymal cells. We analyzed the roles of proliferation and apoptosis in SHPT progression. Seventy-four parathyroid glands from 36 HD patients with SHPT, and 10 parathyroid glands from 10 non-HD patients without SHPT were used for analysis. The former were classified as diffuse (N = 17), early (N = 22), nodular (N = 20), and single (N = 15); the latter were classified as normal (N = 10). To analyze proliferating cells we used Ki-67, and to detect apoptotic cells, we used the terminal deoxynucleotidyl transferase (Tdt)-mediated dUTP nick-end labeling (TUNEL) assay. Concerning the Ki-67 labeling index (LI), the incremental order was single, nodular, early, diffuse, and normal. Oxyphilic cells and around the central portion of each lesion were distinctly stained by Ki-67. Concerning the TUNEL LI, the incremental order was early, diffuse, nodular, single, and normal. Chief cells and around the peripheral portion of each lesion were distinctly stained by TUNEL. In the progression from early to nodular, for oxyphilic cells, the Ki-67 LI increased and the TUNEL LI decreased; for chief cells, the Ki-67 LI decreased and the TUNEL LI showed no significant change. We considered that proliferative activity increases and that the apoptosis rate decreases as SHPT progresses from diffuse to single. Moreover, the specific differences in the rate of proliferation and apoptosis between oxyphilic and chief cells might be associated with SHPT progression.