Diagnosis of asymptomatic primary hyperparathyroidism: proceedings of the third international workshop

Management of surgical diseases of Primary Hyperparathyroidism: indications of the United Italian Society of Endocrine Surgery (SIUEC)

A task force of the United Italian society of Endocrine Surgery (SIUEC) was commissioned to review the position statement on diagnostic, therapeutic and health‑care management protocol in parathyroid surgery published in 2014, at the light of new technologies, recent oncological concepts, and tailored approaches. The objective of this publication was to support surgeons with modern rational protocols of treatment that can be shared by health-care professionals, taking into account important clinical, healthcare and therapeutic aspects, as well as potential sequelae and complications. The task force consists of 12 members of the SIUEC highly trained and experienced in thyroid and parathyroid surgery. The main topics concern diagnostic test and localization studies, mode of admission and waiting time, therapeutic pathway (patient preparation for surgery, surgical treatment, postoperative management, management of major complications), hospital discharge and patient information, outpatient care and follow-up, outpatient initial management of patients with pHPT.

Evaluation of the thiazide challenge test to differentiate primary from hypercalciuria-related hyperparathyroidism

CONTEXT

treatment of primary hyperparathyroidism (PHPT) and secondary hyperparathyroidism due to idiopathic hypercalciuria (SHPT-IH) is markedly different. Robust diagnostic tools to differentiate between both entities are however lacking.

OBJECTIVE

evaluate the thiazide challenge test (TCT) in clinical practice, its aid in clinical decision making, evaluate the accuracy (sensitivity, specificity) and potentially useful parameters of the TCT.

DESIGN

monocentric observational retrospective cohort study from January 2017 to November 2023.

SETTING

outpatient, Ghent University Hospital (Belgium).

PATIENTS

25 adult patients with hypercalciuria, elevated parathyroid hormone (PTH), and high-normal or elevated serum calcium that underwent a TCT.

INTERVENTION

TCT.

OUTCOME MEASURES

serum, urinary biochemical parameters before and after testing, clinical and imaging outcomes, treatment, and follow-up.

RESULTS

patients with a TCT-based working diagnosis of PHPT show greater increases in albumin-adjusted calcium and total serum calcium concentration than patients with SHPT-IH (+0,11 ± 0,10 vs. + 0,0071 ± 0,10mmol/l; p = 0,025 and +0,14 ± 0,12 vs. + 0,012 ± 0,15mmol/l; p = 0,024 respectively). The TCT-based working diagnosis of PHPT has a sensitivity of 81,8%, a specificity of 77,8% and a likelihood ratio of 3,68 of estimating a correct final diagnosis.Urinary calcium excretion, PTH, calcium-phosphorous ratio, PTH-inhibition rate, and parathyroid function index do not differ significantly in patients with PHPT compared to those with SHPT-IH.

CONCLUSION

the TCT aids in discriminating patients with PHPT from those with SHPT-IH based on a rise in serum calcium. Other parameters are not different between both groups. Larger prospective trials are necessary to further define the diagnostic potential of the TCT, its most appropriate biochemical outcome variables, and decision cut-offs.

Prevalence and clinical features of armadillo repeat-containing 5 mutations carriers in a single center cohort of patients with bilateral adrenal incidentalomas

OBJECTIVE

We aimed to evaluate the prevalence of armadillo repeat-containing 5 (ARMC5) genetic defects in our cohort of bilateral adrenal incidentaloma (BAI) patients and to evaluate the possible existence of genotype-phenotype correlations.

DESIGN

Cross-sectional study.

SETTING

Tertiary care center.

PARTICIPANTS

72 BAI patients.

MAIN OUTCOME MEASURE(S)

The following data have been collected: morning adrenocorticotropic hormone (ACTH) concentrations; cortisol levels after 1 mg overnight dexamethasone suppression test (F-1mgDST); urinary free cortisol (UFC) levels; diameter of the adrenal masses; and the association with overweight/obesity, arterial hypertension, diabetes mellitus, dyslipidemia, cardiovascular events, unrelated neoplasia, osteoporosis, thyroid nodular disease, and primary hyperparathyroidism. A search for ARMC5 germline and somatic pathogenic variants was performed in all patients and in the adrenal tissue of patients operated on, respectively.

RESULTS

The prevalence of germline ARMC5 pathogenic variants among patients with mild autonomous cortisol secretion (MACS+, defined as F-1mgDST > 1.8 µg/dL) was 18.8%. No germline pathogenic variants were detected in patients without MACS. Moreover, somatic ARMC5 pathogenic variants were also found in the adrenal tissue of six patients without germline ARMC5 variants. The F-1mgDST levels >5 µg/dL predicted with a poor sensitivity but a 90.5% specificity in identifying the presence of ARMC5 germline pathogenic variants. We did not find any clinical parameter predictive of the ARMC5 mutation presence.

CONCLUSIONS

In MACS+ BAI patients, germline ARMC5 gene pathogenic variants are frequent. Further studies are needed to elucidate the pathophysiological role of somatic ARMC5 pathogenic variants on adrenal tumor development in otherwise wild-type (WT) patients.

GCM2 Variants in Familial and Multiglandular Primary Hyperparathyroidism

CONTEXT

Multiglandular and familial parathyroid disease constitute important fractions of primary hyperparathyroidism (PHPT). Germline missense variants of GCM2, a regulator of parathyroid development, were observed in familial isolated hyperparathyroidism and sporadic PHPT. However, as these previously reported GCM2 variants occur at relatively high frequencies in the population, understanding their potential clinical utility will require both additional penetrance data and functional evidence relevant to tumorigenicity.

OBJECTIVE

Determine the frequency of GCM2 variants of interest among patients with sporadic multigland or familial parathyroid disease and assess their penetrance.

DESIGN AND PATIENTS

DNA-encoding PHPT-associated GCM2 germline variants were polymerase chain reaction-amplified and sequenced from 107 patients with either sporadic multigland or suspected/confirmed familial parathyroid tumors.

RESULTS

GCM2 variants were observed in 9 of 107 cases (8.4%): Y282D in 4 patients (6.3%) with sporadic multigland disease; Y394S in 2 patients (11.1%) with familial PHPT and 3 (4.8%) with sporadic multigland disease. Compared with the general population, Y282D was enriched 5.9-fold in multigland disease, but its penetrance was very low (0.02%). Y394S was enriched 79-fold in sporadic multigland disease and 93-fold in familial PHPT, but its penetrance was low (1.33% and 1.04%, respectively).

CONCLUSIONS

Observed in vitro-activating GCM2 variant alleles are significantly overrepresented in PHPT patients with multiglandular or familial disease compared to the general population, yet penetrance values are very low; that is, most individuals with these variants in the population have a very low risk of developing PHPT. The potential clinical utility of detecting these GCM2 variants requires further investigation, including assessing their possible role as pathogenic/low-penetrance alleles.

The effects of season (spring versus autumn) on diagnosis of normocalcemic primary hyperparathyroidism

BACKGROUND

Raised parathormone (PTH) and normal calcium concentrations can be observed both in normocalcemic primary hyperparathyroidism (nPHPT) and in secondary hyperparathyroidism, e.g. due to vitamin D deficiency. We assessed the impact of season on the validity of diagnosis of nPHPT in terms of screening investigations to be performed in the primary care settings.

MATERIAL AND METHODS

On two occasions (March/April & September/October) we measured vitamin D (25OHD), PTH and total calcium in 125 healthy subjects, age range 6-50, not taking any vitamin D supplements.

RESULTS

In autumn there was an increase in 25OHD concentrations (from 18.1 ± 7.37ng/ml to 24.58 ± 7.72ng/ml, p<0.0001), a decline in PTH from 44.40 ± 17.76pg/ml to 36.63 ± 14.84pg/ml, p<0.001), without change in calcium levels. Only 45 subjects (36%) were vitamin D sufficient (25OHD>20/ml) in spring versus 83 (66.4%) in autumn, p<0.001. Elevated PTH concentrations were noted in 10 subjects in spring (8%) and in six subjects (4.8%) (p<0.05) in autumn. In spring, however, eight out of ten of these subjects (80%) had 25OHD<20 ng/ml, versus one in six (16.7%) in autumn (p<0.01). Normalization of PTH was observed in seven out ten subjects (70%), and all of them had 25-OHD<20 ng/ml in spring.

CONCLUSIONS

In spring elevated PTH concentrations in the setting of normocalcemia are more likely to be caused by 25OHD deficiency rather by nPHPT. In contrast, in autumn, increased PTH concentrations are more likely to reflect nPHPT. We postulate that screening for nPHPT should be done in 25OHD replete subjects, i.e. in autumn rather than in spring.

Factors Associated with Bone Mineral Density and Bone Resorption Markers in Postmenopausal HIV-Infected Women on Antiretroviral Therapy: A Prospective Cohort Study

The study aimed to determine factors associated with changes in bone mineral density (BMD) and bone resorption markers over two years in black postmenopausal women living with human immunodeficiency virus (HIV) on antiretroviral therapy (ART). Women (n = 120) aged > 45 years were recruited from Potchefstroom, South Africa. Total lumbar spine and left femoral neck (LFN) BMD were measured with dual energy X-ray absorptiometry. Fasting serum C-Telopeptide of Type I collagen (CTx), vitamin D and parathyroid hormone were measured. Vitamin D insufficiency levels increased from 23% at baseline to 39% at follow up. In mixed linear models serum CTx showed no change from baseline to end (p = 0.363, effect size = 0.09). Total and LFN BMD increased significantly over two years, but effect sizes were small. No significant change in spine BMD over time was detected (p = 0.19, effect size = 0.02). Age was significantly positively associated with CTx over time, and negatively with total and LFN BMD. Physical activity (PA) was positively associated with LFN BMD (p = 0.008). Despite a decrease in serum vitamin D, BMD and CTx showed small or no changes over 2 years. Future studies should investigate PA interventions to maintain BMD in women living with HIV.

Inactivation of parathyroid hormone: perspectives of drug discovery to combating hyperparathyroidism

Hormonal coordination is tightly regulated within the human body and thus regulates human physiology. The parathyroid hormone (PTH), a member of the endocrine system, regulates the calcium and phosphate level within the human body. Under non-physiological conditions, PTH levels get upregulated (hyperparathyroidism) or downregulated (hypoparathyroidism) due to external or internal factors. In the case of hyperparathyroidism, elevated PTH stimulates cellular receptors present in the bones, kidneys, and intestines to increase the blood calcium level, leading to calcium deposition. This eventually causes various symptoms including kidney stones. Currently, there is no known medication that directly targets PTH in order to suppress its function. Therefore, it is of great interest to find novel small molecules or any other means that can modulate PTH function. The molecular signaling of PTH starts by binding of its N-terminus to the G-protein coupled PTH1/2 receptor. Therefore, any intervention that affects the N-terminus of PTH could be a lead candidate for treating hyperparathyroidism. As a proof-of-concept, there are various possibilities to inhibit molecular PTH function by (i) a small molecule, (ii) N-terminal PTH phosphorylation, (iii) fibril formation and (iv) residue-specific mutations. These modifications put PTH into an inactive state, which will be discussed in detail in this review article. We anticipate that exploring small molecules or other means that affect the N-terminus of PTH could be lead candidates in combating hyperparathyroidism.

Normocalcemic and Normohormonal Primary Hyperparathyroidism: Laboratory Values and End-Organ Effects

OBJECTIVE

Variants of primary hyperparathyroidism (pHPT), described as normocalcemic (NC) and normohormonal (NH), can confuse the diagnosis of classic pHPT.

DATA SOURCES

A MEDLINE search was performed for variants of pHPT using the PubMed database (last queried October 2019).

REVIEW METHODS

The search was restricted to articles published after 1960 that were specific to humans. Studies were included in our analysis if laboratory values and incidence of end-organ involvement were reported for NCpHPT and NHpHPT variants. The search returned 189 articles; 27 additional studies were identified and included for a total of 216. Non-English-language studies were excluded. Abstracts were screened, full-text articles were then assessed, and 82 articles were excluded. Data were pooled using a random-effects model in studies that compared NC or NH pHPT to classic pHPT. Comparative laboratory values are presented.

CONCLUSION

This analysis compares NCpHPT and NHpHPT to classic pHPT. Nephrolithiasis was 21.7% (NCpHPT), 15.9% (classic pHPT), and 25.4% (NHpHPT). Decreased bone mineral density was 49.7% (NCpHPT), 39.7% (classic pHPT), and 40.3% (NHpHPT). Fractures in the NCpHPT group were not significantly different from the classic pHPT. Hypertension in the NCpHPT group was significantly less than classic pHPT (odds ratio, 0.59; 95% CI, 0.40-0.88).

IMPLICATIONS FOR CLINICAL PRACTICE

This information may serve to inform clinicians of the laboratory subtleties of these variants that are being seen with greater frequency in contemporary practice.

Normocalcaemic hyperparathyroidism and primary hyperparathyroidism: least significant change for adjusted serum calcium

INTRODUCTION

The least significant change (LSC) is a term used in individuals in order to evaluate whether one measurement has changed significantly from the previous one. It is widely used when assessing bone mineral density (BMD) scans. To the best of our knowledge, there no such estimate available in the literature for patients with disorders of calcium metabolism. Our aim was to provide an estimate of the least significant change for albumin-adjusted calcium in patients with normocalcaemic hyperparathyroidism (NPHPT) and primary hyperparathyroidism (PHPT).

METHODS

We used the within-subject standard deviatio calculated in a population of NPHPT and PHPT patients and multiplied it by 2.77.

RESULTS

The LSC for NPHPT and PHPT were found to be 0.25 and 0.24 mmol/L, respectively (1.00 and 0.96 mg/dL). In clinical practice, the value of 0.25 mmol/L could be used.

DISCUSSION

The least significant change given, could be used in two ways in these patients. First, it gives a range to which values are expected. This can provide some reassurance for the patient and the physician in cases of intermittent hypercalcaemia. Moreover, it can be a marker of whether an individual has an actual significant change of his calcium after parathyroid surgery.

Normocalcaemic primary hyperparathyroidism: An update on diagnostic and management challenges

Normocalcaemic primary hyperparathyroidism is a condition that can present with intermittent hypercalcemia or may evolve into hypercalcemic primary hyperparathyroidism. This milder biochemical entity remains incompletely understood because of a lack of long-term health outcomes regarding both medical and surgical approaches to its management. Medical therapies have shown some efficacy. A limited number of studies have found that bisphosphonates increase bone mineral density, and calcimimetics may decrease the risk of nephrolithiasis in patients with normocalcaemic primary hyperparathyroidism. Studies have also described patient outcomes after applying the same surgical criteria used for patients with hypercalcaemic primary hyperparathyroidism to those with the normocalcaemic form of the disease. These studies suggest that parathyroid surgery appears to be effective in normalizing elevated serum parathyroid hormone concentrations and decreasing adverse renal and skeletal outcomes in patients with normocalcaemic hyperparathyroidism. Given the available data and overall lack of consensus regarding the optimal management of these patients, a reasonable approach is to tailor treatment to the individual patient by considering their risk factors for new or accelerated bone loss, kidney stones, diminished quality of life, and cardiovascular disease.

Clinical, Biochemical, and Radiological Profile of Normocalcemic Primary Hyperparathyroidism

CONTEXT

The clinical and radiological aspects of normocalcemic hyperparathyroidism (NHPT) are confounded by the differing methods used to rule out secondary hyperparathyroidism and by the small sample size.

OBJECTIVE

To assess the clinical, biochemical, and radiological profile of NHPT compared with primary hyperparathyroidism (PHPT) and control subjects.

DESIGN

Multicentric cross-sectional study.

SETTING

Outpatient clinic.

PATIENTS

47 NHPT, 41 PHPT, and 39 age- and sex-matched control subjects.

MAIN OUTCOME MEASURES

Calcium metabolism and bone turnover markers (BTMs). Lumbar spine, total hip, femoral neck, one-third distal radius bone mineral density (BMD). Morphometric vertebral fracture (VF) assessed by dual-energy X-ray absorptiometry.

RESULTS

NHPT patients had significantly higher parathyroid hormone, 25(OH)-vitamin D levels and lower calcium × phosphorus product than controls (P < .001). Compared with PHPT, the NHPT group had significantly higher 25(OH) vitamin D levels (P = .016). NHPT had BTM levels similar to controls and PHPT. NHPT, PHPT, and controls have similar lumbar spine and femoral neck BMD. NHPT and controls had a similar radial BMD, while patients with PHPT had a lower radial BMD than both patients with NHPT (P = .031) and controls (P < .05). Using the control group as the reference, after adjustment for interacting factors, there was no increase in risk of moderate-severe VF in NHPT (odds ratio [OR] 1.04, 95% confidence interval [CI] 0.25-4.55), while PHPT had an increased risk (OR 3.81,95% CI 1.15-15.12). Seventy-nine percent of NHPT and 59% of PHPT patients fulfilled the criteria for asymptomatic hyperparathyroidism.

CONCLUSIONS

The biochemical phenotype of NHPT is intermediate between PHPT and controls. In contrast, the bone phenotype resembles controls with normal bone turnover, no significant BMD impairment, and no increased risk of VF.

Use of data mining in the establishment of age-adjusted reference intervals for parathyroid hormone

BACKGROUND-AIM

Appropriately defined reference values are of vital importance for the correct interpretation of laboratory results. However, the implementation of in-house reference intervals by traditional methods is rare due to difficulties in the selection of reference individuals, so indirect methods are often alternatively used. Parathyroid hormone (PTH) is a crucial hormone for the metabolism of calcium and phosphorus whose result can lead to erroneous diagnoses and medical actions if adequate reference intervals are not readily available. Our goal was to obtain reference values ​​for adult population for PTH by using data mining. Based on possible new reference intervals, we also aimed to perform a retrospective evaluation of the individuals mistakenly classified.

METHODS

Retrospective observational study between 2014 and 2019. All requests from individuals aged ≥ 18 years were considered if PTH was requested together with serum creatinine, 25-hydroxyvitamin D, calcium, albumin and phosphate (within their respective reference intervals). PTH was measured on the Cobas e411 platform (Roche). Requests were grouped by age and sex. Differences among partitions were assessed by the Harris-Boyd's test and reference intervals were determined by the non-parametrical calculation of percentiles 2.5 and 97.5.

RESULTS

A total of 2279 laboratory requests were included. Reference intervals for PTH were seen to be sex-independent, but age-dependent reference intervals were needed: 18-39, 40-59 and >60 years. Based on the reference intervals obtained, up to 20.1% of individuals were misclassified.

CONCLUSIONS

Appropriateness of PTH reference intervals would lead to a reduction in the number of additional tests and avoid wrong medical actions, thus improving not only patient safety, but also the healthcare system as a whole.

Normocalcemic Hyperparathyroidism: Study of its Prevalence and Natural History

CONTEXT

Normocalcemic hyperparathyroidism (NPHPT) is characterized by persistently normal calcium levels and elevated parathyroid hormone (PTH) values, after excluding other causes of secondary hyperparathyroidism. The prevalence of the disease varies greatly and the data on the natural history of this disease are sparse and inconclusive.

OBJECTIVES

The objectives of this study are to describe the prevalence of NPHPT and its natural history in a referral population and to compare the variability of serum calcium with a group of patients with primary hyperparathyroidism (PHPT).

DESIGN

A retrospective study was conducted over 5 years.

SETTING

The setting for this study was a metabolic bone referral center.

PATIENTS

A total of 6280 patients were referred for a bone mineral density measurement (BMD).

MAIN OUTCOME MEASURES

The prevalence and natural history of NPHPT and variability of calcium were the main outcome measures.

RESULTS

We identified NPHPT patients using data from the day of the BMD measurement. We excluded patients with low estimated glomerular filtration rate (eGFR) or vitamin D, or with no measurements available. Based on the evaluation of their medical files, we identified 11 patients with NPHPT (prevalence 0.18%). Only 4 patients had consistent normocalcemia throughout their follow-up, with only 2 also having consistently high PTH. None had consistently normal eGFR or vitamin D.Intermittent hypercalcemia was present in 7 of the 11 NPHPT patients. The mean adjusted calcium was found to be significantly lower in the NPHPT group compared with the PHPT group but higher than the control group. PTH was similar for NPHPT and PHPT. These 2 groups had similar variability in serum calcium.

CONCLUSIONS

NPHPT patients often have episodes of hypercalcemia. We believe that NPHPT is a mild form of PHPT.

Cognition and cerebrovascular function in primary hyperparathyroidism before and after parathyroidectomy

PURPOSE

There are cognitive changes in primary hyperparathyroidism (PHPT) that improve with parathyroidectomy, but the mechanism of cognitive dysfunction has not been delineated. We assessed if cerebrovascular function is impaired in PHPT, improves post-parathyroidectomy and is associated with PTH level and cognitive dysfunction.

METHODS

This is an observational study of 43 patients with mild hypercalcemic or normocalcemic PHPT or goiter. At baseline, cerebrovascular function (dynamic cerebral autoregulation and vasomotor reactivity) by transcranial Doppler and neuropsychological function were compared between all three groups. A subset underwent parathyroidectomy or thyroidectomy, and was compared 6 months post-operatively.

RESULTS

Mean cerebrovascular and neuropsychological function was normal and no worse in PHPT compared to controls preoperatively. Higher PTH was associated with worse intracerebral autoregulation (r = - 0.43, p = 0.02) and worse cognitive performance on some tests. Post-parathyroidectomy, mood improved significantly, but changes did not differ compared to those having thyroidectomy (p = 0.84). There was no consistent improvement in cognition or change in vascular function in either surgical group.

CONCLUSIONS

Although higher PTH was associated with worse intracerebral autoregulation, cerebrovascular function, cognition and mood were normal in mild PHPT. PTX did not improve vascular or cognitive function. The observed improvement in mood cannot be clearly attributed to PTX. Notwithstanding the small sample size, the results do not support changing current criteria for parathyroidectomy to include cognitive complaints. However, the associations between PTH, cognition and cerebral autoregulation merit future studies in those with more severe hyperparathyroidism.

Parathyroid Hormone Measurement in Chronic Kidney Disease: From Basics to Clinical Implications

Accurate measurement of parathyroid hormone (PTH) is crucial for therapeutic decision-making in patients with chronic kidney disease-mineral and bone disorder (CKD-MBD). The second-generation PTH assays, often referred to as “intact PTH” assays, are the current standard and most available assays in clinical practice. However, intact PTH assays measure both full-length biologically active PTH and heterogeneous PTH fragments in the circulation, providing the equivocal value of PTH measurement in patients with CKD-MBD. Due to the variability of PTH assays, preanalytical sample errors, and the phenomenon of end-organ PTH hyporesponsiveness, current CKD-MBD guidelines recommend a wide range for serum PTH targets (2–9 the upper normal limit of the intact PTH assay) in dialysis patients to diminish the risk of developing adynamic bone disease. Nevertheless, a sizeable proportion of CKD patients still experience renal osteodystrophy despite having serum PTH levels within the recommended range. The primary cause of this inconsistency is the analytical interference of various PTH fragments and oxidized PTH forms that considerably accumulate in CKD patients. Therefore, a new mass spectrometry-based assay, which is capable of specifically measuring the whole spectra of PTH fragments, can potentially improve diagnostic accuracy for renal osteodystrophy. However, the effects of different PTH fragments on bone metabolism, vascular calcification, and mortality in CKD patients warrant further research.

Indirect Reference Intervals: Harnessing the Power of Stored Laboratory Data

Reference intervals are relied upon by clinicians when interpreting their patients' test results. Therefore, laboratorians directly contribute to patient care when they report accurate reference intervals. The traditional approach to establishing reference intervals is to perform a study on healthy volunteers. However, the practical aspects of the staff time and cost required to perform these studies make this approach difficult for clinical laboratories to routinely use. Indirect methods for deriving reference intervals, which utilise patient results stored in the laboratory's database, provide an alternative approach that is quick and inexpensive to perform. Additionally, because large amounts of patient data can be used, the approach can provide more detailed reference interval information when multiple partitions are required, such as with different age-groups. However, if the indirect approach is to be used to derive accurate reference intervals, several considerations need to be addressed. The laboratorian must assess whether the assay and patient population were stable over the study period, whether data 'clean-up' steps should be used prior to data analysis and, often, how the distribution of values from healthy individuals should be modelled. The assumptions and potential pitfalls of the particular indirect technique chosen for data analysis also need to be considered. A comprehensive understanding of all aspects of the indirect approach to establishing reference intervals allows the laboratorian to harness the power of the data stored in their laboratory database and ensure the reference intervals they report are accurate.

Normocalcemia but still elevated parathyroid hormone levels after parathyroidectomy

Even when laboratory results at first match with clinical assessment, assay interference should still be on a clinician's mind when later results no longer fit with the patient.

Primary hyperparathyroidism

In this Review, we describe the pathogenesis, diagnosis and management of primary hyperparathyroidism (PHPT), with a focus on recent advances in the field. PHPT is a common endocrine disorder that is characterized by hypercalcaemia and elevated or inappropriately normal serum levels of parathyroid hormone. Most often, the presentation of PHPT is asymptomatic in regions of the world where serum levels of calcium are routinely measured. In addition to mild hypercalcaemia, PHPT can manifest with osteoporosis and hypercalciuria as well as with vertebral fractures and nephrolithiasis, both of which can be asymptomatic. Other clinical forms of PHPT, such as classical disease and normocalcaemic PHPT, are less common. Parathyroidectomy, the only curative treatment for PHPT, is recommended in patients with symptoms and those with asymptomatic disease who are at risk of progression or have subclinical evidence of end-organ sequelae. Parathyroidectomy results in an increase in BMD and a reduction in nephrolithiasis. Various medical therapies can increase BMD or reduce serum levels of calcium, but no single drug can do both. More data are needed regarding the neuropsychological manifestations of PHPT and the pathogenetic mechanisms leading to sporadic PHPT, as well as on risk factors for complications of the disorder. Future work that advances our knowledge in these areas will improve the management of the disorder.

The surgical management of primary hyperparathyroidism: an updated review

Patients with primary hyperparathyroidism often present clinically asymptomatic with various biochemical compositions of serum calcium, parathyroid hormone, vitamin D and urinary calcium. Understanding the subtle differences in clinical and biochemical presentations is key for timely diagnosis and referral to an experienced parathyroid surgeon. Surgery remains the only option for cure of primary hyperparathyroidism, which now favors a directed parathyroidectomy with intra-operative adjuncts. However it is important to understand and revise the surgical approach for patients with hereditary conditions or nonlocalizing studies. Revised guidelines from the Fourth International Workshop on the Management of Asymptomatic Primary Hyperparathyroidism in 2013 and the American Association of Endocrine Surgeons in 2016 are reviewed in this paper for an updated review of this condition.

Parathyroid hormone: Data mining for age-related reference intervals in adults

OBJECTIVE

Age-related changes in parathyroid hormone (PTH) have been previously documented in adults. However, because of the limitations of traditional approaches to establishing reference intervals, age-related reference intervals have not been defined. We sought to use a data mining approach to derive age-related PTH reference intervals.

DESIGN AND PARTICIPANTS

Results from patients undergoing PTH testing over a 4-year period were extracted from the database of a private pathology laboratory in New South Wales, Australia. Patients were included in the study if they were 18 years or older and had simultaneous determination of PTH, serum calcium, estimated glomerular filtration rate and 25-hydroxyvitamin D (25-OHD). Patients with abnormalities of serum calcium or renal function were excluded.

MEASUREMENTS

Bhattacharya analysis of log-transformed data was used to derive age-related PTH reference intervals across adulthood.

RESULTS

Results were available for 33 652 subjects. Among patients with optimal 25-OHD status, older age was associated with higher PTH concentrations. Age-related reference intervals were derived and showed a 63% increase in the upper and lower reference limits between the youngest (18-29 years of age) and the oldest (80 years of age or older) age partitions. The appropriateness of using a single reference interval for patients of all ages was evaluated against objective criteria and was found to be unsatisfactory.

CONCLUSIONS

Data mining was demonstrated to be a useful tool for establishing age-related PTH reference intervals. The technique demonstrated that increasing age is associated with higher PTH concentrations and that age-related reference intervals are important for accurate result interpretation.

Current opinions on nephrolithiasis associated with primary hyperparathyroidism

Nephrolithiasis is a common urological disease and could be secondary to primary hyperparathyroidism (PHPT). PHPT is traditionally characterised with hypercalcaemia. Recently, a normocalcemic PHPT has been officially recognised at the International Workshops. Regarding this new phenotype, nephrolithiasis is frequently found in studies that evaluate low bone mass. However, until now, no study on aetiology of nephrolithiasis considered normocalcemic PHPT. Hypercalciuria related to PHPT is considered as an important risk factor of stone formation in hypercalcemic PHPT, but the precise relationships between hypercalcemic PHPT and nephrolithiasis and between normocalcemic PHPT and nephrolithiasis remain unclear. In patients with hypercalcemic PHPT, after a surgical cure of PHPT, the renal calcium excretion and stone recurrence rate reduce but remain higher above health controls. This finding implies that abnormalities not caused by PHPT also probably affect stone formation. According to the new guideline, the presence of stones indicates the need for parathyroidectomy in patients with either hypercalcemic or normocalcemic PHPT unless contraindications exist. Patients with contraindications for parathyroidectomy or those who do not want to receive parathyroidectomy should be monitored for signs of disease progression and given of medical management. Moreover, due to decreased but significantly higher frequency of nephrolithiasis above those of healthy controls, patients with nephrolithiasis associated with PHPT after parathyroidectomy still should be motivated to explore strategies to prevent stone occurrence.

Familial Hypocalciuric Hypercalcemia as an Atypical Form of Primary Hyperparathyroidism

Familial hypocalciuric hypercalcemia (FHH) causes lifelong hypercalcemia with features that overlap with typical primary hyperparathyroidism (PHPT). The incompleteness of this overlap has led to divergent nomenclatures for FHH. I compare two nomenclatures. One sets FHH as an entity distinct from PHPT. The other groups FHH with PHPT but conditions FHH as atypical PHPT. I analyzed selected articles about calcium-sensing receptors, FHH, PHPT, CASR, GNA11, and AP2S1. FHH usually results from a heterozygous germline inactivating mutation of the CASR, and less frequently from mutation of GNA11 or AP2S1. The CASR encodes the calcium-sensing receptors. These are highly expressed on parathyroid cells, where they sense serum calcium concentration and regulate suppression of PTH secretion by serum calcium. Their mutated expression in the kidney in FHH causes increased renal tubular reabsorption of calcium (hypocalciuria). Many FHH features are shared with PHPT and thus support FHH as a form of PHPT. These include a driver mutation expressed mainly in the parathyroid cells. The mutation causes a parathyroid cell insensitivity to extracellular calcium in vivo and in vitro, a right-shift of the set point for suppression of PTH secretion by calcium. Serum PTH is normal or mildly elevated; ie, it is not appropriately suppressed by hypercalcemia. Total parathyroidectomy causes hypoparathyroidism and durable remission of hypercalcemia. Some other features are not shared with PHPT and could support FHH as a distinct entity. These include onset of hypercalcemia in the first week of life, frequent persistence of hypercalcemia after subtotal parathyroidectomy, and hypocalciuria. The features supporting FHH as a form of PHPT are stronger than those favoring FHH as a distinct entity. Classifying FHH as an atypical form of PHPT represents compact nomenclature and supports current concepts of pathophysiology of FHH and PHPT. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Skeletal Microstructure and Estimated Bone Strength Improve Following Parathyroidectomy in Primary Hyperparathyroidism

CONTEXT

High-resolution peripheral quantitative computed tomography (HRpQCT) is a noninvasive imaging technology that can provide insight into skeletal microstructure and strength. In asymptomatic primary hyperparathyroidism (PHPT), HRpQCT imaging has demonstrated both decreased cortical and trabecular indices, consistent with evidence for increased fracture risk. There are limited data regarding changes in HRpQCT parameters postparathyroidectomy.

OBJECTIVE

To evaluate changes in skeletal microstructure by HRpQCT in subjects with PHPT after parathyroidectomy.

DESIGN

We studied 29 subjects with PHPT (21 women, 8 men) with HRpQCT at baseline and 6, 12, 18, and 24 months postparathyroidectomy.

MAIN OUTCOME MEASURES

Volumetric bone mineral density, microarchitectural indices, and finite element analysis at the distal radius and tibia.

RESULTS

At both the radius and tibia, there were significant improvements in total, cortical, and trabecular volumetric bone density as early as 6 months postparathyroidectomy (24-month values for total volumetric bone density, radius: +2.8 ± 4%, tibia: +4.4 ± 4%; P < 0.0001 for both), cortical thickness (radius: +1.1 ± 2%, tibia: +2.0 ± 3%; P < 0.01 for both), and trabecular bone volume (radius: +3.8 ± 5%, tibia: +3.2 ± 4%; P < 0.0001 for both). At both sites, by finite element analysis, stiffness and failure load were improved starting at 6 months postparathyroidectomy (24-month values for failure load, radius: +6.2 ± 6%, tibia: +4.8 ± 7%; P < 0.0001 for both).

CONCLUSIONS

These results provide information about skeletal microarchitecture in subjects with PHPT followed through 2 years after parathyroidectomy. Estimated bone strength is improved, consistent with data showing decreased fracture risk postparathyroidectomy.

Primary hyperparathyroidism associated to thrombocytopenia: an issue to consider?

Primary hyperparathyroidism (PHPT) is probably the most common endocrine disorder of the parathyroid glands, causing hypercalcemia. It is diagnosed often in persons with elevated serum calcium levels. However, hematological manifestations, such as thrombocytopenia are less known. In this case we describe the possible association of PHPT with reversible thrombocytopenia after parathyroidectomy. This hematological abnormality can be included in the spectrum of possible causes, including seemingly non-specific symptoms, in the decision tree towards surgical assessment.

How the reference values for serum parathyroid hormone concentration are (or should be) established?

Well-validated reference values are necessary for a correct interpretation of a serum PTH concentration. Establishing PTH reference values needs recruiting a large reference population. Exclusion criteria for this population can be defined as any situation possibly inducing an increase or a decrease in PTH concentration. As recommended in the recent guidelines on the diagnosis and management of asymptomatic primary hyperparathyroidism, PTH reference values should be established in vitamin D-replete subjects with a normal renal function with possible stratification according to various factors such as age, gender, menopausal status, body mass index, and race. A consensus about analytical/pre-analytical aspects of PTH measurement is also needed with special emphasis on the nature of the sample (plasma or serum), the time and the fasting/non-fasting status of the blood sample. Our opinion is that blood sample for PTH measurement should be obtained in the morning after an overnight fast. Furthermore, despite longer stability of the PTH molecule in EDTA plasma, we prefer serum as it allows to measure calcium, a prerequisite for a correct interpretation of a PTH concentration, on the same sample. Once a consensus is reached, we believe an important international multicentre work should be performed to recruit a very extensive reference population of apparently healthy vitamin D-replete subjects with a normal renal function in order to establish the PTH normative data. Due to the huge inter-method variability in PTH measurement, a sufficient quantity of blood sample should be obtained to allow measurement with as many PTH kits as possible.

Differences in single gland and multigland disease are seen in low biochemical profile primary hyperparathyroidism

BACKGROUND

Primary hyperparathyroidism is characterized by increased levels of serum calcium and parathyroid hormone. Recently, 2 additional mild biochemical profiles have emerged, normocalcemic and normohormonal primary hyperparathyroidism. We reviewed our surgical experience of mild biochemical profile patients and compared them with classic primary hyperparathyroidism patients.

METHODS

This is a single institution, retrospective cohort review of all patients who underwent parathyroidectomy for primary hyperparathyroidism from 2006-2012. Preoperative and intraoperative variables were analyzed. Univariable analysis was performed with analysis of variance and the χ² test. A logistic regression was performed to identify significantly independent predictor variables for multigland disease.

RESULTS

A total of 573 patients underwent parathyroidectomy for primary hyperparathyroidism (classic, n = 405; normohormonal, n = 96; normocalcemic, n = 72). Normocalcemic primary hyperparathyroidism was associated with multigland disease in 43 (45%, P < .001) patients as compared with the normohormonal (7, 10%) and classic (36, 9%) groups. On logistic regression, significant predictors for multigland disease were the normocalcemic subtype and positive family history. Twelve month biochemical normalization rates after operative treatment were >98% in all 3 groups.

CONCLUSION

Our series shows that normocalcemic primary hyperparathyroidism is associated with a high incidence of multigland disease. Normohormonal disease is similar to classic disease patients with >90% presenting with single adenomas. Excellent rates of biochemical normalization can be obtained by operative treatment in all 3 groups.

The Biochemical Profile of Familial Hypocalciuric Hypercalcemia and Primary Hyperparathyroidism during Pregnancy and Lactation: Two Case Reports and Review of the Literature

Background. Primary hyperparathyroidism (PHPT) and Familial Hypocalciuric Hypercalcemia (FHH) result in different maternal and fetal complications in pregnancy. Calcium to creatinine clearance ratio (CCCR) is commonly used to help distinguish these two conditions. Physiological changes in calcium handling during pregnancy and lactation can alter CCCR, making it a less useful tool to distinguish PHPT from FHH. Cases. A 25-year-old female presented with hypercalcemia and an inappropriately normal PTH. Her CCCR was 0.79% before pregnancy and rose to 1.99% in her second trimester. The proband's mother and neonate had asymptomatic hypercalcemia. Genetic analysis revealed a CaSR mutation consistent with FHH. A 19-year-old female presented with a history of nephrolithiasis who underwent emergent caesarean section at 29 weeks of gestation for severe preeclampsia. At delivery, she was diagnosed with hypercalcemia with an inappropriately normal PTH and a CCCR of 2.67%, which fell to 0.88% during lactation. Parathyroidectomy cured her hypercalcemia. Pathology confirmed a parathyroid adenoma. Conclusion. These cases illustrate the influence of pregnancy and lactation on renal calcium indices, such as the CCCR. To avoid diagnostic error of women with hypercalcemia during pregnancy and lactation, calcium biochemistry of first-degree relatives and genetic testing of select patients are recommended.

Perspective and priorities for improvement of parathyroid hormone (PTH) measurement - A view from the IFCC Working Group for PTH

Parathyroid hormone (PTH) measurement in serum or plasma is a necessary tool for the exploration of calcium/phosphate disorders, and is widely used as a surrogate marker to assess skeletal and mineral disorders associated with chronic kidney disease (CKD), referred to as CKD-bone mineral disorders (CKD-MBD). CKD currently affects >10% of the adult population in the United States and represents a major health issue worldwide. Disturbances in mineral metabolism and fractures in CKD patients are associated with increased morbidity and mortality. Appropriate identification and management of CKD-MBD is therefore critical to improving clinical outcome. Recent increases in understanding of the complex pathophysiology of CKD, which involves calcium, phosphate and magnesium balance, and is also influenced by vitamin D status and fibroblast growth factor (FGF)-23 production, should facilitate such improvement. Development of evidence-based recommendations about how best to use PTH is limited by considerable method-related variation in results, of up to 5-fold, as well as by lack of clarity about which PTH metabolites these methods recognise. This makes it difficult to compare PTH results from different studies and to develop common reference intervals and/or decision levels for treatment. The implications of these method-related differences for current clinical practice are reviewed here. Work being undertaken by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) to improve the comparability of PTH measurements worldwide is also described.

Parathyroid hormone and the risk of incident hypertension: the Atherosclerosis Risk in Communities study

BACKGROUND

Recent evidence suggests that parathyroid hormone (PTH) has effects on vascular smooth muscle cells, the rennin-angiotensin system and kidney function, but less is known about its role in the development of hypertension. The distribution of serum PTH also varies by race.

METHODS AND RESULTS

Therefore, we examined the relation between PTH and incident hypertension and tested for interaction by race among 7504 Atherosclerosis Risk in Communities participants (1264 black, 6240 white, median age 56 years) without initial hypertension in 1990-1992. During a median follow-up of 6 years, 1487 white and 509 black participants developed hypertension. In the overall study population, PTH was not associated with incident hypertension after adjustment for demographics and behavioral risk factors [hazard ratio highest vs. lowest quintiles, 95% confidence interval: 1.11 (0.96-1.28); P for linear trend 0.02]. Although the interaction was not statistically significant (P = 0.60), there was some evidence that the PTH-hypertension association differed by race. Among blacks, PTH was positively associated with incident hypertension, independent of demographics, and behavioral risk factors (P for linear trend 0.003). Among whites, PTH was not associated with hypertension risk. Results were similar when comparing participants with elevated versus nonelevated PTH (≥65 vs. <65 pg/ml): hazard ratio in blacks: 1.24 (1.02-1.54); hazard ratio in whites: 0.95 (0.78-1.16).

CONCLUSIONS

In this large community-based cohort, PTH levels, overall, were not independently associated with the risk of hypertension. However, we found some evidence that PTH may be associated with hypertension in blacks. Future research should continue to explore potential race differences in the PTH-hypertension association.

Considerations in parathyroid hormone testing

Parathyroid hormone (PTH) is a major player in phosphocalcic metabolism and its measurement is very important for the correct diagnosis and treatment of several diseases. PTH determination represents the paradigm of quality in laboratory medicine as many variables in the pre-, intra-, and post-analytical phases strongly affect the value of the clinical information. Analytical determination of PTH has been rendered difficult by the presence, in the circulation, of truncated fragments that can cross-react with the antibodies used for its determination. In addition, pre-analytical phase is complicated by the lack of stability of the peptide and the best sample to use for its determination remains controversial, as well as sample handling and storage. PTH secretion is also affected by circadian and seasonal rhythms and by physical exercise. Finally, from the post-analytical perspective, establishment of reliable reference ranges requires further efforts as the selection criteria for reference subjects should take into consideration new variables such as gender, race and vitamin D levels. Finally, clinical guidelines have recently revised and improved the criteria for a correct interpretation of PTH values.

Serum PTH reference values established by an automated third-generation assay in vitamin D-replete subjects with normal renal function: consequences of diagnosing primary hyperparathyroidism and the classification of dialysis patients

OBJECTIVE

To determine parathyroid hormone (PTH) reference values in French healthy adults, taking into account serum 25-hydroxyvitamin D (25OHD), renal function, age, gender, and BMI.

PARTICIPANTS AND MAIN BIOLOGICAL MEASUREMENTS

We studied 898 healthy subjects (432 women) aged 18-89 years with a normal BMI and estimated glomerular filtration rate (eGFR), 81 patients with surgically proven primary hyperparathyroidism (PHPT), and 264 dialysis patients. 25OHD and third-generation PTH assays were implemented on the LIAISON XL platform.

RESULTS

Median PTH and 25OHD values in the 898 healthy subjects were 18.8  ng/l and 23.6  ng/ml respectively. PTH was lower in subjects with 25OHD ≥30  ng/ml than in those with lower values. Among the 183 subjects with 25OHD ≥30  ng/ml, those aged ≥60 years (n=31) had higher PTH values than younger subjects, independent of 25OHD, BMI, and eGFR (P<0.001). Given the small number of subjects aged ≥60 years, we adopted the 95% CI of PTH values for the entire group of 183 vitamin D-replete subjects (9.4-28.9  ng/l) as our reference values. With 28.9  ng/l as the upper limit of normal (ULN) rather than the manufacturer's ULN of 38.4  ng/l, the percentage of PHPT patients with 'high' PTH values rose to 90.1% from 66.6% (P<0.001), and 18.6% of the dialysis patients were classified differently in view of the KDIGO target range (two to nine times the ULN).

CONCLUSION

When only subjects with 25OHD ≥30  ng/ml were included in the reference population, the PTH ULN fell by 22.4%, diagnostic sensitivity for PHPT improved, and the classification of dialysis patients was modified.

Parathyroid hormone is associated with incident diabetes in white, but not black adults: The Atherosclerosis Risk in Communities (ARIC) Study

OBJECTIVE

Accumulating evidence has linked elevated parathyroid hormone (PTH) with insulin resistance, beta cell dysfunction and dysglycaemia, however, its role in the development of diabetes is largely unclear, particularly among non-whites. We sought to examine the association of PTH with the incidence of diabetes.

METHODS

We studied 8066 white and 2034 black adults aged 46-70 years at baseline (1990-92) from the ARIC Study with follow-up for incident diabetes ascertained during study visits conducted in 1993-95 and 1996-98. Hazard ratios (HR) and their 95% CIs for diabetes adjusted for demographics, lifestyle, and 25-hydroxyvitamin D were estimated according to PTH measured at baseline.

RESULTS

PTH was higher among blacks than whites (median [IQR], 43.8 [35.0-55.8] vs. 37.9 [30.4-47.3] pg/mL; P<0.001). During a median follow-up of 6 years, 498 white and 167 black participants developed diabetes. The association of PTH with diabetes varied significantly by race (P-interaction 0.02). PTH was not associated with risk for diabetes among black adults. Among whites, HRs according to quintiles of PTH were 1 (referent), 0.95 (0.71, 1.29), 0.95 (0.70, 1.28), 1.12 (0.84, 1.51), and 1.31 (0.98, 1.76) (P-trend 0.03). When a clinical cut-point for PTH was applied (≥65pg/mL; 5.7% of whites), the HR for diabetes among whites was 1.38 (1.01, 1.88). Results were similar when restricted to participants with normal baseline kidney function.

CONCLUSION

In this large, population-based study, elevated PTH was independently associated with risk for diabetes among white, but not black adults. Further studies are needed to elucidate the mechanisms that may underlie this differential association of PTH with diabetes across race groups.

Reduction of Parathyroid Hormone with Vitamin D Supplementation in Blacks: A Randomized Controlled Trial

BACKGROUND

Response of parathyroid hormone (PTH) to vitamin D supplementation is determined by the baseline PTH level and change in vitamin D status. Conflicting reports in Blacks exist on the PTH response to vitamin D to supplementation.

METHODS

During 3 winters from 2007-2010, 328 healthy Blacks (median age, 51 years) living in Boston, MA were randomized into a 4-arm, double-blind trial for 3 months of placebo, 1000, 2000, or 4000 IU of vitamin D3. PTH was measured in 254 participants at baseline and at the end of vitamin D supplementation period.

RESULTS

The differences in PTH between baseline and 3 months were 3.93 pg/mL for those receiving placebo, -3.37 pg/mL for those receiving 1000 IU/d, -6.76 pg/mL for those receiving 2000 IU/d, and -8.99 pg/mL for those receiving 4000 IU/d ( -2.98 pg/mL for each additional 1000 IU/d of vitamin D3; p<0.001).

CONCLUSION

We found a significant decrease in PTH with increasing doses of vitamin D supplementation up to intakes of 4000 IU/d in Blacks. Clinical Trials.gov: NCT00585637.

An overview of normocalcemic primary hyperparathyroidism

PURPOSE OF REVIEW

Normocalcemic primary hyperparathyroidism (PHPT) received special attention in the publication of the conference proceedings from the Fourth International Workshop on the Management of Asymptomatic PHPT, although much remains unknown about the disorder.

RECENT FINDINGS

Observational studies have found that despite maintaining normocalcemia, patients with normocalcemic PHPT have a high incidence of kidney stones and osteoporosis. Small studies focusing on the cardiovascular implications of normocalcemic PHPT have shown a possible association with hypertension and an atherogenic lipid profile, but not insulin resistance. Recent data from small cohorts show that subjects with normocalcemic PHPT respond to medical therapy and have a positive densitometric response following parathyroid surgery.

SUMMARY

The available evidence suggests that patients with normocalcemic PHPT develop complications of PHPT, despite having normal calcium levels. Most data come from referral populations and information regarding a mild, asymptomatic form of the disease is lacking. Future research requires a standardized approach to the diagnostic criteria of normocalcemic PHPT.

Low vitamin D levels have become less common in primary hyperparathyroidism

We compared temporal trends in serum 25-hydroxyvitamin D and parathyroid hormone (PTH) in two primary hyperparathyroidism (PHPT) cohorts recruited 20 years apart. The prevalence of 25-hydroxyvitamin D levels <20 and <30 ng/mL declined by 30-50 %, respectively, and was accompanied by lower PTH. In the older cohort, higher PTH may be due to lower 25-hydroxyvitamin D.

INTRODUCTION

Vitamin D deficiency may exacerbate PHPT. Whether there have been temporal trends in 25-hydroxyvitamin D (25OHD) levels in PHPT is unclear. The prevalence of low vitamin D levels (25OHD <20 and <30 ng/mL) and associated biochemical and bone mineral density (BMD) profiles were assessed in two PHPT cohorts recruited over 20 years apart.

METHODS

This is a cross-sectional comparison of serum 25OHD levels, calciotropic hormones, and BMD between two PHPT cohorts recruited at the same hospital: the "old" (N = 103) and "new" (N = 100) cohorts were enrolled between 1984 and 1991 and between 2010 and 2014, respectively.

RESULTS

Mean 25OHD levels were 26 % higher in the new cohort (23 ± 10 vs. 29 ± 10 ng/mL, p < 0.0001). Levels of 25OHD <20 and <30 ng/mL declined from 46 and 82 %, respectively, to 19 and 54 % (both p < 0.0001). Supplemental vitamin D use was common in the new (64 %) but not the old cohort (0 %). The new cohort demonstrated 33 % lower serum PTH levels (p < 0.0001). Neither serum nor urine calcium differed. BMD was higher in the new cohort at all skeletal sites (all p < 0.001).

CONCLUSION

With the rise in vitamin D supplementation over the last two decades, low 25OHD levels are no longer common in PHPT patients in the New York area. Those with 25OHD <20 and <30 ng/mL have declined by over 50 and 30 %, respectively. The lower mean PTH levels in the new cohort are most likely accounted for by higher vitamin D intake. Whether improved vitamin D status also underlies the relatively higher BMD in the more vitamin D replete cohort of PHPT patients is unknown.

Vitamin D in Primary Hyperparathyroidism: Effects on Clinical, Biochemical, and Densitometric Presentation

CONTEXT

Vitamin D (25-hydroxyvitamin D [25OHD]) deficiency (<20 ng/mL) and insufficiency (20-29 ng/mL) are common in primary hyperparathyroidism (PHPT), but data regarding their skeletal effects in PHPT are limited.

OBJECTIVE

The objective was to evaluate the association between 25OHD levels and PHPT severity.

DESIGN, SETTINGS, AND PARTICIPANTS

This is a cross-sectional analysis of 100 PHPT patients with and without 25OHD insufficiency and deficiency from a university hospital setting.

OUTCOME MEASURES

We measured calciotropic hormones, bone turnover markers, and bone mineral density (BMD) by dual x-ray absorptiometry.

RESULTS

Lower 25OHD was associated with some (PTH: r = -0.42; P < .0001; 1,25-dihydroxyvitamin D: r = -0.27; P = .008; serum PO4: r = 0.31; P = .002) but not all (serum/urine calcium) indicators of PHPT severity. Lower 25OHD was also associated with younger age, higher body mass index, male gender, better renal function, and lower vitamin D intake. Comparison of those with deficient (<20 ng/mL; 19%) vs insufficient (20-29 ng/mL; 35%) vs replete (≥30 ng/mL; 46%) 25OHD demonstrated more severe PHPT as reflected by higher PTH (mean ± SEM, 126 ± 10 vs 81 ± 7 vs 72 ± 7 pg/mL; P < .0001) but no difference in nephrolithiasis, osteoporosis, fractures, serum or urinary calcium, bone turnover markers, or BMD after adjustment for age and weight. In women, T-scores at the 1/3 radius were lower in those with 25OHD of 20-29 ng/mL, compared to those who were vitamin D replete (P = .048). In multiple regression modeling, 25OHD (but not PTH) was an independent predictor of 1/3 radius BMD.

CONCLUSION

Vitamin D deficiency is associated with more severe PHPT as reflected by PTH levels, but effects on BMD are limited to the cortical 1/3 radius and are quite modest. These data support international guidelines that consider PHPT patients with 25OHD <20 ng/mL to be deficient. However, in this cohort with few profoundly vitamin D-deficient patients, vitamin D status did not appear to significantly impact clinical presentation or bone density.

Secondary osteoporosis and metabolic bone disease in patients 50 years and older with osteoporosis or with a recent clinical fracture: a clinical perspective

PURPOSE OF REVIEW

The purpose of this review is to provide guidance to clinicians about which laboratory tests should be performed in patients with osteoporosis or with a recent fracture.

RECENT FINDINGS

Newly diagnosed secondary osteoporosis and other metabolic bone diseases (SECOB) have been found in 5-48% of patients with osteoporosis. In patients with a recent fracture, new SECOB is found in 10-47% of patients with osteoporosis, and in 26-51% if all patients with a fracture regardless of bone mineral density (BMD) are screened. More than one SECOB can be found in the same patient, even when they have already known SECOB. In primary hyperparathyroidism, hyperthyroidism, hypercortisolism, and multiple myeloma, both SECOB and its treatment have an impact on BMD and fractures. For other SECOBs, no treatment is available, or there are no data about the effect of treatment of the SECOB on BMD and fractures.

SUMMARY

We recommend performing the following tests in all patients with osteoporosis or a recent clinical fracture: calcium, phosphate, creatinine, albumin, erythrocyte sedimentation rate in all patients, 24 h urine calcium in men and serum testosterone in men less than 70 years. On indication, additional tests can be performed.

[Cervical sympathetic chain schwannoma associated with parathyroid adenoma]

BACKGROUND

Schwannoma is a rare benign tumor derived from nerve sheaths. When derived from the cervical sympathetic chain, it usually presents itself as an asymptomatic mass located in the posterior cervical region, at paravertebral level. Its diagnosis is not easy, usually requiring multiple imaging tests. Its differential diagnosis includes parathyroid adenoma.

CLINICAL CASE

A new case of schwannoma of the cervical sympathetic chain in a patient with a synchronous overactive parathyroid adenoma is reported. This case adds to the sixty described in the literature, although to our knowledge no association between schwannoma and parathyroid adenoma has been reported to date.

CONCLUSIONS

Despite being a benign tumor, its treatment is a complete surgical resection. The most common complication after the surgery needed for these tumors is ipsilateral Horner syndrome.

Cinacalcet normalizes serum calcium in a double-blind randomized, placebo-controlled study in patients with primary hyperparathyroidism with contraindications to surgery

OBJECTIVE

Primary hyperparathyroidism (PHPT) is diagnosed by the presence of hypercalcemia and elevated or nonsuppressed parathyroid hormone (PTH) levels. Although surgery is usually curative, some individuals fail or are unable or unwilling to undergo parathyroidectomy. In such individuals, targeted medical therapy may be of value. Cinacalcet normalized calcium level and lowered PTH in patients with PHPT in several phase 2 and open-label studies. We compared cinacalcet and placebo in subjects with PHPT unable to undergo parathyroidectomy.

DESIGN

Phase 3, double-blind, multi centere, randomized, placebo-controlled study.

METHODS

Sixty-seven subjects (78% women) with moderate PHPT were randomized (1:1) to cinacalcet or placebo for ≤28 weeks.

MAIN OUTCOME MEASURE

Achievement of a normal mean corrected total serum calcium concentration of ≤10.3 mg/dl (2.575 mmol/l).

RESULTS

Baseline median (quartile 1 (Q1), Q3) serum PTH was 164.0 (131.0, 211.0) pg/ml and mean (s.d.) serum Ca was 11.77 (0.46) mg/dl. Serum Ca normalized (≤10.3 mg/dl) in 75.8% of cinacalcet- vs 0% of placebo-treated subjects (P<0.001). Corrected serum Ca decreased by ≥1.0 mg/dl from baseline in 84.8% of cinacalcet- vs 5.9% of placebo-treated subjects (P<0.001). Least squares mean (s.e.m.) plasma PTH change from baseline was -23.80% (4.18%) (cinacalcet) vs -1.01% (4.05%) (placebo) (P<0.001). Similar numbers of subjects in the cinacalcet and placebo groups reported adverse events (AEs) (27 vs 20) and serious AEs (three vs four). Most commonly reported AEs were nausea and muscle spasms.

CONCLUSIONS

These results demonstrate that cinacalcet normalizes serum calcium in this PHPT population and appears to be well tolerated.

The evaluation and treatment of endocrine forms of hypertension

Endocrine hypertension is an important secondary form of hypertension, identified in between 5% and 10% of general hypertensive population. Primary aldosteronism is the most common cause of endocrine hypertension, accounting for 1%-10% in uncomplicated hypertension and 7%-20% in resistant hypertension. Other less common causes of endocrine hypertension include Cushing syndrome, pheochromocytoma, thyroid disorders, and hyperparathyroidism. Diagnosis requires a high index of suspicion and the use of appropriate screening tests based on clinical presentation. Failure to make proper diagnosis may lead to catastrophic complications or irreversible hypertensive target organ damage. Accordingly, patients who are suspected to have endocrine hypertension should be referred to endocrinologists or hypertension specialists who are familiar with management of the specific endocrine disorders.