Normocalcemic primary hyperparathyroidism: From pathophysiology to clinical management.

Normocalcemic primary hyperparathyroidism (NPHPT), a variant of primary hyperparathyroidism (PHPT) characterized by persistently elevated parathyroid hormone (PTH) levels and normal serum calcium, has gained recognition as a substantial subset of PHPT cases. Despite its increasing prevalence, the precise pathophysiology and natural progression of NPHPT remain enigmatic. This in-depth literature review explores recent advancements in our understanding of NPHPT, encompassing pathophysiology, clinical presentation, diagnostic approaches, medical and surgical management options. By synthesizing this wealth of information, this review aims to contribute to a more nuanced and informed approach to the treatment of patients grappling with NPHPT. As our understanding of the condition continues to evolve, the knowledge gathered from this review has the potential to significantly enhance the quality of care and outcomes for individuals afflicted with NPHPT, ultimately improving their overall well-being and prognosis.

The effect of parathyroidectomy compared to non-surgical surveillance on kidney function in primary hyperparathyroidism: a nationwide historic cohort study.

BACKGROUND: Patients with primary hyperparathyroidism (pHPT) and impaired kidney function (estimated glomerular filtration rate (eGFR) < 60 mL/min) are offered parathyroidectomy (PTX) to protect them from further complications. Surprisingly, two recent uncontrolled cohort studies have suggested a further decrease in kidney function following PTX. We aimed to examine the effects of PTX compared to non-surgical surveillance on kidney function in pHPT patients. METHODS: Historic cohort study. From the Danish National Patient Registry (NPR) and major medical biochemistry laboratories in Denmark, we identified 3585 patients with biochemically confirmed pHPT among whom n = 1977 (55%) were treated with PTX (PTX-group) whereas n = 1608 (45%) were followed without surgery (non-PTX group). Baseline was defined as time of diagnosis and kidney function was re-assessed 9-15 months after PTX (PTX group) or 9-15 months after diagnosis (non-PTX group). RESULTS: At follow-up, eGFR had decreased significantly in the PTX- compared to the non-PTX-group (median - 4% vs. - 1%, p < 0.01). Stratification by baseline eGFR showed that the decrease was significant for those with a baseline eGFR value of 80-89 and > 90 mL/min, but not for those with lower eGFR values. Findings did not differ between patients with mild compared to moderate/severe hypercalcemia. However, after mutual adjustments, we identified baseline levels of calcium, PTH, and eGFR as well as age and treatment (PTX vs. no-PTX) as independent predictors for changes in kidney function. CONCLUSION: Compared to non-surgical surveillance, PTX is associated with a small but significant decrease in kidney function in pHPT patients with an initial normal kidney function.

Adenoma paratiroideo mediastínico gigante. Abordaje cervical y toracoscópico. Caso clínico / Gigant Mediastinal Parathyroid Adenoma. Cervical and Thoracoscopic Approach. Case Report

El hiperparatiroidismo primario es el tercer trastorno endocrino más común, alrededor del 85% de los casos se debe a adenomas paratiroideos. El tratamiento definitivo es la paratiroidectomía, siendo la causa más común de fracaso la resección inadecuada y la localización de tejido ectópico, representando un desafío para el cirujano. En el presente trabajo se presenta el caso de un paciente con diagnóstico de adenoma paratiroideo mediastínico gigante, siendo este el de mayor longitud descrito en la literatura en los últimos 10 años. Caso clínico: Paciente masculino de 70 años de edad quien consulta por presentar convulsiones, polidipsia y poliuria. Se determinan niveles elevados de PTH, hipercalcemia e hipofosfatemia. Estudios de imagen describen lesión alargada localizada en espacio paratraqueal derecho extendiéndose hasta el polo inferior de lóbulo tiroideo derecho. Se decide resolución quirúrgica, mediante la realización de cervicotomía y toracoscopia con evolución satisfactoria del paciente. Conclusión: Los adenomas paratiroideos ectópicos constituyen una causa común de falla quirúrgica e hiperparatiroidismo persistente, su sospecha es de gran importancia. El tratamiento definitivo es la cirugía. La localización preoperatoria por pruebas de imagen es fundamental para seleccionar correctamente la técnica quirúrgica y garantizar el éxito de la cirugía. El abordaje cervical y toracoscópico es una alternativa segura y eficaz(AU)

Primary hyperparathyroidism is the third most common endocrine disorder, about 85% of cases are due to parathyroid adenomas. The definitive treatment is parathyroidectomy, being the most frequent cause of failure the inadequate resection and the location of ectopic tissue. The ectopic parathyroid adenomas represent a challenge for the surgeon. In this paper a case of a patient diagnosed with giant mediastinal parathyroid adenoma is presented, and is the largest reported in the literature in the last 10 years. Clinical case: 70-year-old male patient presented with seizures, polydipsia and polyuria, reason for which he consults. Elevated PTH levels, hypercalcemia, and hypophosphatemia are determined. Imaging studies report an elongated lesion located in the right paratracheal space that extends to the lower pole of the right thyroid lobe. Surgical resolution was decided, by performing cervicotomy and thoracoscopy with satisfactory recovery of the patient. Conclusion: Ectopic parathyroid adenomas are a common cause of surgical failure and persistent hyperparathyroidism; their suspicion is of great importance. The definitive treatment is surgery. Preoperative localization through imaging tests is essential to correctly select the surgical technique and guarantee the success of the surgery, the cervical and thoracoscopic approach is a safe and effective alternative(AU)

A detailed appraisal of renal manifestations in primary hyperparathyroidism from Indian PHPT registry: Before and after curative parathyroidectomy.

BACKGROUND: Primary hyperparathyroidism (PHPT) is a systemic disorder characterized by hypercalcaemia and inappropriately elevated parathyroid hormone (PTH). Renal manifestations are one of the main presenting features both in symptomatic and asymptomatic PHPT patients. OBJECTIVES: We aimed to compare demographic, clinical and biochemical parameters of PHPT patients with and without renal manifestations and also analysed the influence of curative parathyroidectomy on renal functions. METHODS: We retrospectively analysed the data of PHPT patients from the last 25 years (1995- March 2019) and compared the demographic and clinical presentation and biochemical measurements between patients with and without renal manifestations and evaluated the changes in renal functions after 1 year of curative parathyroidectomy. RESULTS: Of the total 544 PHPT patients, 299 (55%) including 91 out of 141 (65%) males had renal manifestations. Among renal manifestations, nephrolithiasis and nephrocalcinosis were found in 41.7% and 27.6% PHPT patients, respectively. PHPT patients with renal manifestations had significantly higher creatinine (109.7 vs 79.6 µmol/L; P < .0001) and lower eGFR level (78.8 vs 93.9 mL/min/1.73 m2 ; P < .0001) compared to patients without renal manifestations. Parathyroidectomy resolved the clinical symptoms with biochemical cure in the patients from both the groups. Patients with renal manifestations showed improvement in creatinine and eGFR levels after 1 year of curative parathyroidectomy; however, patients without renal manifestations showed no change in creatinine and eGFR levels. CONCLUSION: Young age and male gender are predictors of renal manifestations in PHPT. Curative parathyroidectomy improves renal functions in PHPT patients with renal manifestations compared to PHPT patients without renal manifestation.

FGF23 and primary hyperparathyroidism: is there a link?

INTRODUCTION: Data regarding the role of fibroblast growth factor 23 (FGF23) in primary hyperparathyroidism (PHPT) are scarce and discordant. Our study aimed to evaluate the prognostic impact of FGF23 upon the clinical and biochemical evolution of PHPT. MATERIAL AND METHODS: Forty-two patients with ages between 30 and 80 years, diagnosed with PHPT caused by a sporadic, solitary parathyroid adenoma, and referred to surgery (minimally invasive parathyroidectomy) were prospectively included in the study. Serum levels of FGF23, PTH, 25(OH)D3, calcium (Ca), phosphate (P), total procollagen type 1 N-terminal propeptide, and C-terminal telopeptide of type I collagen were determined at baseline (preoperatory), one day after surgery, and in 13 patients also prospectively at three, six, and 12 months. Bone mineral density (BMD) was also evaluated before surgery in all patients and 12 months after surgery in the 13 followed up patients. RESULTS: In the 42 PHPT patients with D hypovitaminosis (mean 25(OH)D3 levels of 16.2 ± 1.5 ng/mL), preoperatory serum FGF23 concentration was within the normal range (75.55 ± 3.39 pg/mL) and remained unchanged one day post operation (81.69 ± 4.67 pg/mL, p = non-significant). The 13 patients followed prospectively for up to 12 months after surgery also showed unmodified FGF23 levels (80.9 ± 11.03 pg/mL, p = non-significant), despite PTH and Ca normalisation and vitamin D replenishment. Preoperatory FGF23 negatively correlated with PTH (r = -0.37, p = 0.038), but not with 25(OH)D3, Ca, P, bone mass, or metabolism markers. CONCLUSIONS: In PHPT, correlations between FGF23 and PTH seem rather an epiphenomenon. Therefore, we think that FGF23 evaluation and dynamics are not informative regarding PHPT severity. (Endokrynol Pol 2020; 71 (4): 306-312).

Measurement of the AST to LD Ratio in Parathyroid Tissue Suspension Can Precisely Differentiate a Hyperfunctioning Parathyroid.

BACKGROUND: Frozen section of excised tissue is used to confirm removal of the etiology of primary hyperparathyroidism in the current era of intraoperative parathyroid hormone measurement and provides safeguards for surgeons. We recently reported that the aspartate aminotransferase (AST)/lactate dehydrogenase (LD) ratio in tissue suspension can accurately distinguish normal parathyroid tissue from other tissues. Therefore, we hypothesized that this ratio may also be applied to distinguish hyperfunctioning parathyroid tissue (HPT) from other tissues. METHODS: We prospectively analyzed 22 patients who underwent parathyroidectomy for primary hyperparathyroidism (benign, 21; malignant, 1) from July 2018 to October 2019. In total, 27 specimens were examined. Approximately 1 mm3 of minced HPT as confirmed by frozen sections was suspended in 1 mL of normal saline and AST and LD levels were measured. The AST/LD ratios of other tissues (normal parathyroid tissue, thyroid gland, adipose tissue, and others; n = 94) were obtained from our previous report. RESULTS: The AST/LD ratio of benign HPT was consistently higher than that of other tissues (P < 0.001). The optimal cut-off value was 0.36 according to the receiver operating characteristic curve, with 100% sensitivity and specificity. The AST/LD ratio in malignant HPT was also markedly lower than that in benign HPT. CONCLUSION: This method might be a new adjunct for intraoperative differentiation of HPT with an accuracy and turnaround time comparable with those of frozen sections, minimal cost, and no need for dedicated pathological staff. Additionally, this method might increase the treatment success rate in settings with limited medical resources.

Functional magnetic resonance imaging in primary hyperparathyroidism.

OBJECTIVE: The neurophysiological mechanisms underlying cognitive dysfunction in primary hyperparathyroidism (PHPT) and the brain regions affected are not clear. We assessed neural activation during cognitive testing (matrix reasoning, paired associates, and logical memory) using functional MRI (fMRI) in 23 patients with PHPT and 23 healthy controls. A subset with PHPT was re-assessed 6 months post-parathyroidectomy (PTX). DESIGN: This is an observational study comparing neural activation by fMRI in patients with PHPT to normative controls. Postmenopausal women were studied at a tertiary referral center. RESULTS: There were no between-group differences in cognitive task performance. Patients with PHPT had lower neural activation vs controls (max Z = 4.02, all P < 0.01) during matrix reasoning in brain regions involved in executive function (left frontal lobe (k = 57) and right medial frontal gyrus (k = 72)) and motor function (right precentral gyrus (k = 51)). During paired associates (verbal memory), those with PHPT had greater activation in the right inferior parietal lobule (language/mathematical operations; k = 65, P < 0.01). Greater activation in this region bilaterally correlated with higher PTH (k = 96, P < 0.01). Post-PTX, activation decreased during matrix reasoning, but in different regions than those affected pre-PTX. CONCLUSIONS: PHPT is associated with differences in task-related neural activation patterns, but no difference in cognitive performance. While this may indicate compensation to maintain the same cognitive function, there was no clear improvement in neural activation after PTX. Larger, longitudinal studies that include PHPT patients followed without surgery are needed to determine if PTX could prevent worsening of altered neural activation patterns in PHPT.

Persistence of "non-dipping" pattern in blood pressure after curative parathyroidectomy in apparently normotensive patients with symptomatic primary hyperparathyroidism.

BACKGROUND: The prevalence of hypertension in primary hyperparathyroidism (PHPT) varies from 20-80% with data being based on office-based blood pressure measurements. Little is known about ambulatory monitoring of blood pressure (AMBP) in PHPT and changes in blood pressure (BP) variables post-curative parathyroidectomy. Hence, we conducted a prospective study wherein we performed AMBP in apparently normotensive patients with PHPT and reevaluated them 3 months post-curative parathyroidectomy. METHODS: Consecutive patients with symptomatic PHPT aged 20 years and above underwent 24 hours AMBP at enrollment and at 3 months after successful parathyroidectomy. Pre- and postoperative BP variables were compared and correlated with serum calcium, creatinine and intact parathyroid hormone (iPTH) levels. RESULTS: After exclusion, 17 symptomatic PHPT patients were enrolled in the study. AMBP detected hypertension in 4 (23.5%) patients. There was a significant reduction in the average nighttime systolic (P=0.007) and diastolic BP (P=0.034) after parathyroidectomy. However, the average 24 hours systolic/diastolic BP, daytime systolic/diastolic BP and average 24 hours mean arterial pressure did not differ before and after surgery. Non-dipping blood pressure pattern was seen in 53% of patients at presentation and persisted in 50% of cases after successful surgery. None of the biochemical parameters significantly correlated with any BP variable. CONCLUSIONS: AMBP can help detect hypertension in patients with PHPT that remains unrecognized with routine office-based blood pressure measurement. In addition, AMBP detects loss of normal dipping pattern in BP that persists in almost half of the patients even after successful parathyroidectomy, perhaps because of permanent vascular damage induced by PHPT.

18F-Fluorocholine PET/CT in Primary Hyperparathyroidism: Superior Diagnostic Performance to Conventional Scintigraphic Imaging for Localization of Hyperfunctioning Parathyroid Glands.

Primary hyperparathyroidism (PHPT) is a common endocrine disorder, definitive treatment usually requiring surgical removal of the offending parathyroid glands. To perform focused surgical approaches, it is necessary to localize all hyperfunctioning glands. The aim of the study was to compare the efficiency of established conventional scintigraphic imaging modalities with emerging 18F-fluorocholine PET/CT imaging in preoperative localization of hyperfunctioning parathyroid glands in a larger series of PHPT patients. Methods: In total, 103 patients with PHPT were imaged preoperatively with 18F-fluorocholine PET/CT and conventional scintigraphic imaging methods, consisting of 99mTc-sestamibi SPECT/CT, 99mTc-sestamibi/pertechnetate subtraction imaging, and 99mTc-sestamibi dual-phase imaging. The results of histologic analysis, as well as intact parathyroid hormone and serum calcium values obtained 1 d after surgery and on follow-up, served as the standard of truth for evaluation of imaging results. Results: Diagnostic performance of 18F-fluorocholine PET/CT surpassed conventional scintigraphic methods (separately or combined), with calculated sensitivity of 92% for PET/CT and 39%-56% for conventional imaging (65% for conventional methods combined) in the entire patient group. Subgroup analysis, differentiating single and multiple hyperfunctioning parathyroid glands, showed PET/CT to be most valuable in the group with multiple hyperfunctioning glands, with sensitivity of 88%, whereas conventional imaging was significantly inferior, with sensitivity of 22%-34% (44% combined). Conclusion:18F-fluorocholine PET/CT is a diagnostic modality superior to conventional imaging methods in patients with PHPT, allowing for accurate preoperative localization.

Effect of Parathyroidectomy on Cardiovascular Risk Factors in Primary Hyperparathyroidism: A Randomized Clinical Trial.

CONTEXT: It remains unclear whether risk of cardiovascular diseases is increased in patients with mild (<1.45 mmol/L) to moderate (≥1.45 to 1.60 mmol/L) primary hyperparathyroidism (PHPT). OBJECTIVE: We aimed to determine the short-term effect of parathyroidectomy (PTX) on arterial stiffness, cholesterol levels, and blood pressure (BP). DESIGN: This study was a clinical trial randomly allocating patients to either PTX or a control group (no surgery). Follow-up was performed 3 months after surgery in the PTX group and 3 months after baseline in the control group. SETTING: University hospital. PARTICIPANTS: We recruited 79 patients with PHPT; 69 participants completed the study. MAIN OUTCOMES: Office and ambulatory 24-hour BP, pulse wave velocity (PWV), augmentation index, and fasting plasma cholesterol levels. RESULTS: At baseline, participants had a median level of ionized calcium of 1.41 mmol/L (range, 1.33 to 1.60 mmol/L) and PTH of 10.4 pmol/L (4.5 to 30.4 pmol/L). Median age was 64 years (range, 18 to 81) and 72% were females. Following PTX, plasma total cholesterol levels decreased significantly compared with the controls (P = 0.04). Changes in PWV, augmentation index, and ambulatory 24-hour BP did not differ between groups, except for an increase in ambulatory diastolic BP following PTX. However, in patients with baseline levels of ionized calcium ≥1.45 mmol/L, PWV decreased significantly in response to PTX compared with the control group (P = 0.03). CONCLUSION: PTX may decrease risk of cardiovascular diseases in PHPT by lowering total cholesterol levels, although ambulatory diastolic BP increases in response to surgery. Patients with moderate to severe hypercalcemia may benefit from PTX by a decrease in PWV.

Evaluation of endothelial function and diastolic function in patients with primary hyperparathyroidism before and after parathyroidectomy.

INTRODUCTION: Primary hyperparathyroidism (PHPT) is the leading cause of outpatient hypercalcemia associated with increased cardiovascular risk. The flow-mediated vasodilation (FMV) has been proposed as a non-invasive method for assessing endothelial function. OBJECTIVE: To compare the endothelial dysfunction measured by FMV and diastolic dysfunction in patients with PHPT before and after parathyroidectomy. METHOD: We performed a quasi-experimental (before-after) study to evaluate diastolic function and FMV in patients with PHPT before and six months after parathyroidectomy. RESULTS: Fifteen patients completed study: 12 women and 3 men; 73% presented lithiasis, 27% osteoporosis and 53% metabolic syndrome; 73% presented diastolic dysfunction before the surgery and 60% after the surgery (p = 0.09). Post-isquemia brachial diameter improved from 41 mm (before surgery) to 46 mm (after surgery; p = 0.020). After surgery, we also observed an increase in the brachial diameter pre vs. post-ischemia from 41 to 46 mm (p = 0.005). Before surgery, the change in the delta of brachial diameter pre and post-ischemia was 1 mm and up to 4 mm after surgery (p = 0.03). CONCLUSIONS: There is a minor endothelial dysfunction measured by FMV in patients who underwent surgery for PHPT at 6 months after surgery, as well as a trend towards improvement in diastolic dysfunction. Echocardiography can be useful in the preoperative evaluation in patients with asymptomatic PHPT.

INTRODUCCIÓN: El hiperparatiroidismo primario (HPTP) es la principal causa de hipercalcemia ambulatoria y se ha asociado con un riesgo cardiovascular elevado. La vasodilatación mediada por flujo (VMF) es un método no invasivo que evalúa la función endotelial. OBJETIVO: Comparar la disfunción endotelial mediante VMF y la disfunción diastólica en pacientes con HPTP antes y después de la paratiroidectomía. MÉTODO: Mediante un estudio cuasiexperimental (antes-después) se evaluaron la función diastólica y la VMF antes y 6 meses después de realizar una paratiroidectomía. RESULTADOS: Se incluyeron 15 pacientes con HPTP: 12 mujeres (80%) y 3 hombres (20%); el 73% presentaron litiasis, el 27% osteoporosis y el 53% síndrome metabólico; el 73% tenían disfunción diastólica antes de la cirugía y el 60% después de la cirugía (p = 0.09). Los diámetros braquiales post-isquemia mejoraron de 41 mm antes de la cirugía a 46 mm tras la cirugía (p = 0.020). Así mismo, los diámetros braquiales preisquemia vs. post-isquemia después de la cirugía mejoraron de 41 a 46 mm (p = 0.005). Antes de la cirugía, el cambio en la delta del diámetro braquial preisquemia y post-isquemia fue de 1 mm, y subió a 4 mm después de la cirugía (p = 0.03). CONCLUSIONES: Existe una menor disfunción endotelial medida por VMF en pacientes posoperados por HPTP a los 6 meses de la cirugía. El estudio ecocardiográfico puede ser de utilidad en la evaluación preoperatoria de los pacientes con HPTP asintomáticos.

Factors associated with glomerular filtration rate variation in primary hyperparathyroidism after parathyroidectomy

Background/aim: Prolonged hypercalcemia impairs renal function, and a reduced glomerular filtration rate (GFR) is typical in advanced primary hyperparathyroidism (PHPT). There are scarce data related to predictors of renal impairment in patients with PHPT. Hence, we aimed to evaluate changes in kidney function in PHPT patients after parathyroidectomy (PTX) and identify factors associated with GFR variation in these patients. Materials and methods: One hundred and twenty-five patients with PHPT who underwent surgery between 2012 and 2014 were enrolled in the study. Patients were divided into two groups according to GFR values: patients whose GFR was lower than 60 mL/min/1.73 m2 and higher than 60 mL/min/1.73 m2. Demographic and laboratory parameters were compared before and 6 months after parathyroidectomy. Results: Prevalence of antihypertensive drug users and patients with renal cysts and parathormone (PTH) and alkaline phosphatase levels were higher in patients with GFR of ≥60 than in GFR of <60 mL/min/1.73 m2 (P < 0.05). Systolic BP, uric acid, and magnesium were decreased in patients with GFR of ≥60, but GFR did not change in the two groups after parathyroidectomy. After parathyroidectomy, calcium and PTH decreased but 25(OH)D3 and phosphorus increased in the two groups. In multiple regression analysis, age, calcium, and baseline GFR were independent predictors of GFR variation. Parathyroid adenoma volume and urinary calcium were not independent predictors of GFR change. Conclusion: Olderage, higher preoperative calcium, and GFR were factors associated with GFR increase in PHPT patients after parathyroidectomy. Further renal impairment was prevented by parathyroidectomy in PHPT patients

Normocalcemic Hyperparathyroidism.

Parathyroid hormone (PTH) disorders are characterized by a wide spectrum of clinical and biochemical presentations. The increasing use of serum PTH assay in the set of the diagnostic workout in patients with osteoporosis has identified patients with features of surgically confirmed primary hyperparathyroidism (PHPT) associated with persistent normal serum calcium levels, which has been recognized as a distinct entity from hypercalcemic PHPT (HPHPT) by the last international consensus. Normocalcemic PHPT (NPHPT) affects about 6-8% of PHPT patients. Although hypercalcemia is absent, patients with NPHPT experience kidney, bone, and cardiovascular impairments similar to those observed in HPHPT, suggesting that NPHPT may significantly affect the health of patients. Diagnosis of NPHPT requires an intensive diagnostic workup aimed to: (1) exclude all causes of secondary hyperparathyroidism, and (2) evaluate the occurrence of PTH-related diseases. The management of NPHPT is controversial in part due to lack of solid data about the natural history as well as the effects of surgical or medical treatments. Nonetheless, a clinical and biochemical follow-up is recommended in order to detect potential progression. When hypercalcemia and/or PTH-related disorders arise, parathyroidectomy can be considered. When surgery is not advisable, medical treatment aimed to increase bone mineral density may be a therapeutic option.

Mild primary hyperparathyroidism-to treat or not to treat?

INTRODUCTION: The presentation of primary hyperparathyroidism (PHPT) has shifted from a disease characterized by renal and skeletal complications to a mild or asymptomatic condition. Modern imaging allows localization of a surgical target in the majority of cases. SOURCES OF DATA: Data were collected from literature searches of online databases including PUBMED, MEDLINE and Cochrane. A narrative review was performed. AREAS OF AGREEMENT: Parathyroidectomy is the only therapy with curative potential with good outcomes and low risk of complications in experienced hands. Current guidelines advocate that surgery is offered in all symptomatic cases and in those who meet criteria depending on age, serum calcium concentration, skeletal and renal parameters. A structured monitoring approach should be offered to those who do not undergo surgery. AREAS OF CONTROVERSY: Thresholds for intervention to improve skeletal and renal outcomes are debatable. In addition, controversy persists over the benefit of surgery for non-skeletal/renal outcomes. GROWING POINTS: The role of medical management of PHPT using agents such as bisphosphonates, denosumab and cinacalcet are discussed. AREAS TIMELY FOR DEVELOPING RESEARCH: In summary, further data on the natural history and effects of treatment of mild and asymptomatic PHPT are required to determine thresholds for surgery. In particular, further investigations of non-skeletal and non-renal parameters, such as neurocognitive quality of life and cardiovascular disease are required. Data on normocalcaemic PHPT are lacking. Large-scale randomized controlled trials would be welcome in these areas, however in view of the cost implications a more pragmatic approach may be to develop collaborative multi-centre registries.

99mTcO4-/99mTc-MIBI dual-tracer scintigraphy for preoperative localization of parathyroid adenomas.

OBJECTIVE: To investigate the accuracy of dual-tracer scintigraphy for locating parathyroid adenomas in patients with primary hyperparathyroidism (PHPT). METHODS: We reviewed 268 patients with PHPT. All patients underwent technetium-99m pertechnetate (99mTcO4-) scintigraphy and technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) dual-tracer scintigraphy of the thyroid and parathyroid glands, respectively. 99mTcO4- planar scintigraphy was carried out initially followed by dual-phase 99mTc-MIBI single-photon emission computed tomography (SPECT)/CT the next day. The findings were combined and interpreted. Individual 99mTc-MIBI and dual-tracer scintigraphy were both analyzed. The sensitivity, specificity, and accuracy were determined in relation to surgical findings. The average interval between scan and surgery was 13 days. RESULTS: The positive and negative predictive values of 99mTc-MIBI SPECT/CT were 92.0% and 71.3%, respectively, and the sensitivity, specificity, and accuracy were 88.3%, 79.2%, and 85.8%, respectively. The positive and negative predictive values of dual-tracer scintigraphy were 96.3% and 82.3%, respectively, and the sensitivity, specificity, and accuracy were 92.9%, 90.3%, and 92.2%, respectively. Youden's index for dual-tracer scintigraphy and 99mTc-MIBI SPECT/CT were 0.83 and 0.63, respectively. CONCLUSIONS: These finding suggest that 99mTcO4- and 99mTc-MIBI dual-tracer scintigraphy is more accurate than other scintigraphy methods for detecting parathyroid adenoma, and may thus be the most suitable imaging technique in patients with PHPT.

The browning of white adipose tissue and body weight loss in primary hyperparathyroidism.

BACKGROUND: Parathyroid hormone related protein (PTHrP) triggers white adipose tissue (WAT) browning and cachexia in lung cancer mouse models. It remains unknown whether excessive PTH secretion affects WAT browning and to what extent it contributes to body weight change in primary hyperparathyroidism (PHPT). METHODS: Using the adeno-associated virus injection, Pth gene over-expressed mice mimicking PHPT were firstly established to observe their WAT browning and body weight alteration. The association between PTH and body weight was investigated in 496 PHPT patients. The adipose browning activities of 20 PHPT and 60 control subjects were measured with PET/CT scanning. FINDINGS: Elevated plasma PTH triggered adipose tissue browning, leading to increased energy expenditure, reduced fat content, and finally decreased body weight in PHPT mice. Higher circulating PTH levels were associated with lower body weight (ß = -0.048, P = .0003) independent of renal function, serum calcium, phosphorus,and albumin levels in PHPT patients. PHPT patients exhibited both higher prevalence of detectable brown/beige adipose tissue (20% vs 3.3%, P = .03) and increased browning activities (SUV in cervical adipose was 0.77 vs 0.49,P = .02) compared with control subjects. INTERPRETATION: Elevated serum PTH drove WAT browning program, which contributed in part to body weight loss in both PHPT mice and patients. These results give insights into the novel pathological effect of PTH and are of importance in understanding the metabolic changes of PHPT. FUND: This research is supported by the National Key Research and Development Program of China and National Natural Science Foundation of China.

Does renal function improve after parathyroidectomy in primary hyperparathyroidism? / ¿Mejora la función renal tras la paratiroidectomía en el hiperparatirodismo primario?

INTRODUCTION: Primary hyperparathyroidism (PHPT) is a common endocrine disorder characterised by hypercalcaemia and parathormone increase. Decreased glomerular filtration rate (<60ml/min) continues to be a parathyroidectomy (PTX) criterion in asymptomatic PHPT. The influence of PTX on renal function evolution is the subject of debate. OBJECTIVE: To analyse the clinical, laboratory and histological characteristics of patients undergoing PHPT, as well as renal function evolution after PTX. MATERIAL AND METHODS: Retrospective study of 297 patients diagnosed with PHPT and referred to surgery in a single centre between 1998 and 2016. Laboratory parameters were determined at baseline, one week and one year after PTX. RESULTS: The Incidence of PTX was 38 cases/million/year. Mean age was 60±14 years and 80.5% of the patients were female. Approximately 65.3% were asymptomatic. Nephrolithiasis was the most common clinical finding (33%), followed by bone involvement (29.5%). PTX indications were: clinical symptoms (34.7%), hypercalcaemia>11.2mg/dl (27%), nephrolithiasis (13%), low bone mass (12%), age<50 years (11%) and decreased glomerular filtration rate<60ml/min (2.3%). For diagnostic localisation, spect-MIBI had a sensitivity of 92% and cervical ultrasound of 70%. A total of 94.3% of PHPT cases were due to a parathyroid adenoma. After PTX, normalisation of PHPT-related parameters was observed. We found a significant increase in serum creatinine levels (0.81 vs 0.85mg/dl, P<.001) from the first week post-PTX until the end of the first year. The renal function was only found to be significant in patients with glomerular filtration rate>60ml/min (baseline serum creatinine levels 0.77mg/dl vs serum creatinine levels after one year 0.81mg/dl, P<.001). CONCLUSIONS: PHPT was asymptomatic in most patients who underwent surgery. Hypercalcaemia and nephrolithiasis were the most common indications of parathyroidectomy in asymptomatic patients. MIBI scan was the most useful localisation method. Surgical treatment of PHPT is followed by renal function impairment, which persists after the first week post-PTX.

Bone mineral density changes after parathyroidectomy are dependent on biochemical profile.

BACKGROUND: Bone mineral density (BMD) has been found to improve after parathyroidectomy (PTX) in patients with primary hyperparathyroidism. There are few data on the effect of PTX on BMD in normocalcemic and normohormonal primary hyperparathyroidism. METHODS: A retrospective analysis of 92 primary hyperparathyroidism patients who underwent PTX between 2004 and 2012 with pre- and post-PTX dual-energy x-ray absorptiometry was performed. Within-person changes in BMD pre- and post-PTX were analyzed using log linear mixed models, stratified by biochemical status. RESULTS: Bone mineral density increased post-PTX in the whole cohort at the lumbar spine (+2.5%), femoral neck (+2.1%), and total hip (+1.9%) and decreased at the one-third radius (-0.9%). On comparison of BMD changes by profile, BMD increased in those with the typical profile at the lumbar spine (3.2%), femoral neck (2.9%), and total hip (2.9%) but declined at the one-third radius (-1.5%). In contrast, BMD improved only at the femoral neck (4.3%) in the normohormonal group and did not change at any site in the normocalcemic group. The typical group had a greater increase in BMD over time at the femoral neck and total hip compared with normocalcemic patients. CONCLUSION: Our results indicate that the skeletal benefit of PTX was attenuated in normocalcemic and normohormonal patients, suggesting that skeletal changes after PTX may depend on biochemical profile.

Acute kidney injury associated with hypercalcaemic crisis in a patient with primary hyperparathyroidism.

Parathyroid or hypercalcaemic crisis is a rare presenting manifestation of primary hyperparathyroidism and usually seen in relation to parathyroid carcinoma and multiple myeloma. We present a middle-aged woman with extreme hypercalcaemia due to parathyroid adenoma presenting as acute kidney injury. This case highlights the need to consider primary hyperparathyroidism in differentials of a patient presenting with severe hypercalcaemia and renal dysfunction. Also this is the second reported case in literature of a patient surviving such extreme hypercalcaemia due to parathyroid adenoma.

Primary Hyperparathyroidism.

Background: Primary hyperparathyroidism (PHPT), the most common cause of hypercalcemia, is most often identified in postmenopausal women. The clinical presentation of PHPT has evolved over the past 40 years to include three distinct clinical phenotypes, each of which has been studied in detail and has led to evolving concepts about target organ involvement, natural history, and management. Methods: In the present review, I provide an evidence-based summary of this disorder as it has been studied worldwide, citing key concepts and data that have helped to shape our concepts about this disease. Results: PHPT is now recognized to include three clinical phenotypes: overt target organ involvement, mild asymptomatic hypercalcemia, and high PTH levels with persistently normal albumin-corrected and ionized serum calcium values. The factors that determine which of these clinical presentations is more likely to predominate in a given country include the extent to which biochemical screening is used, vitamin D deficiency is present, and whether parathyroid hormone levels are routinely measured in the evaluation of low bone density or frank osteoporosis. Guidelines for parathyroidectomy apply to all three clinical forms of the disease. If surgical guidelines are not met, parathyroidectomy can also be an appropriate option if no medical contraindications are present. If either the serum calcium or bone mineral density is of concern and surgery is not an option, pharmacological approaches are available and effective. Conclusions: Advances in our knowledge of PHPT have guided new concepts in diagnosis and management.