Changing biochemical presentation of primary hyperparathyroidism

Primary Hyperparathyroidism due to Parathyroid Adenoma in Children and Adolescents

OBJECTIVE

In contrast to adults, primary hyperparathyroidism (PHPT) in children and adolescents is a rare endocrine disorder.

METHODS

A retrospective review of PHPT cases between 2005 and 2022 from a single tertiary university medical center, including clinical signs and symptoms, laboratory findings, radiological evaluation, treatment, and postoperative complications.

RESULTS

Ten children (mean age at diagnosis 16.3 ± 1.3 years) were diagnosed with PHPT. All patients were in late pubertal stages without sex predominance and 8 were symptomatic. Mean calcium level was 13.6 ± 2.5 mg/dL, and mean parathyroid hormone levels were 204.8 ± 163.1 pg/mL. Parathyroid adenoma was confirmed by the postsurgical pathology results.

CONCLUSIONS

PHPT in children and adolescents is often symptomatic and more severe than adults. The main cause is single parathyroid adenoma. Associated hypercalcemic syndromes were not found. Patients were cured after surgical removal of the adenoma without significant postoperative complications and no recurrence during 10.4 ± 5.9 years follow-up.

Relationship between parathyroid adenoma size, weight and histological subtypes with perioperative serum levels

AIMS

This study aims to identify associations between parathyroid adenoma (PTA) characteristics (histology, weight and size) with the change in parathyroid hormone (PTH) and calcium levels.

METHODS

A historical cohort study was conducted on adult patients with solitary PTA removed in the Gold Coast Health Precinct, Australia, between 2017 and 2022.

RESULTS

PTA weight is correlated with the change in day 1 PTH level (r=0.26, p=0.036), the change in day 1 corrected calcium level (r=0.20, p=0.033), and the change in follow-up corrected calcium level (r=0.47, p<0.001). The largest dimension (size) of PTA is also correlated with the change in day 1 PTH (r=0.30, p=0.011) and the change in follow-up corrected calcium level (r=0.40, p<0.001). Adjusted for age and gender, a statistically significant negative correlation was found between day 1 PTH level and adenoma size, resulting in a 0.5% change in size for every percentage change in PTH level (equating to a 5.0% increase in variance explained, p=0.038). Similarly, a negative correlation was identified in day 1 corrected calcium levels and weight, with a 4.7% change in weight for every percentage of change in day 1 corrected calcium level (an increase of 5.6% variance explained, p=0.010). In addition, a negative correlation was identified, where every 3.1% change in size (an increase of 17.4% variance explained, p<0.001) and 7.6% change in weight (an increase of 22.7% variance explained, p<0.001) was seen with every percentage change in follow-up corrected calcium levels. Clear-cell PTA had the most significant percentage fall in day 1 corrected calcium levels compared with other PTA subtypes (p=0.007).

CONCLUSIONS

Preoperative calcium and PTH levels correlate with PTA weight and size. The degree of change in postoperative corrected calcium levels behaved differently in the clear-cell subtype.

Evaluation of Surgeon-Performed Ultrasonography With or Without Contrast Enhancement vs Scintigraphy in Patients With Primary Hyperparathyroidism

Importance

Scintigraphy and ultrasonography are common imaging modalities for the preoperative localization of enlarged parathyroid glands in primary hyperparathyroidism. When comparing the 2 modalities, the benefits of ultrasonography in terms of convenience, patient comfort, duration, cost, and lack of radiation should be taken into account.

Objective

To investigate whether surgeon-performed ultrasonography, with or without contrast-enhanced ultrasonography (CEUS), is noninferior to scintigraphy for localizing pathological parathyroid glands in patients with primary hyperparathyroidism.

Design, Setting, and Participants

Prospective, paired, noninferiority cohort study performed at a high-volume tertiary referral center for parathyroidectomy with blinded examiners and a 6-month follow-up. Participants were adults (age ≥18 years) referred for parathyroidectomy due to primary hyperparathyroidism. Of 207 eligible patients, 35 were excluded, leaving 172 enrolled in the study. Inclusion lasted from September 2019 until February 2021. Follow-up ended in December 2021.

Exposures

99mTechnetium-pertechnetate/99mtechnetium-sestamibi subtraction scintigraphy with 99mtechnetium-sestamibi single-photon emission computed tomography/computed tomography, followed by surgeon-performed ultrasonography and CEUS.

Main Outcomes and Measures

The sensitivity of each imaging modality in localizing pathological parathyroid glands, calculated on a per-quadrant and a per-patient basis, respectively. The a priori noninferiority margin was a lower 95% confidence limit for the difference in sensitivity not falling below -10%.

Results

Out of 172 participants, 139 (80.8%) were women, the median (range) age was 65 (24-87) years, and the median (IQR) follow-up was 200.5 (181-280.25) days. Quadrant sensitivity (95% CI) was 70.9% (63.2%-78.5%) for ultrasonography, 68.4% (60.4%-76.5%) for ultrasonography plus CEUS, and 67.0% (60.0%-74.0%) for scintigraphy. The sensitivity difference (95% CI) compared with scintigraphy was 3.9% (-4.1% to 11.8%) for ultrasonography and 1.5% (-6.4% to 9.3%) for ultrasonography plus CEUS, establishing noninferiority for both modalities. Per-patient sensitivity was 81.4% (74.8%-86.9%) for ultrasonography and 79.1% (72.2%-84.9%) for both scintigraphy and ultrasonography plus CEUS. The sensitivity difference compared with scintigraphy was 2.3% (-6.8% to 11.4%) for ultrasonography and 0.0% (-9.1% to 9.1%) for ultrasonography plus CEUS, establishing noninferiority for both modalities.

Conclusions and Relevance

In this cohort study, conventional ultrasonography by an experienced parathyroid surgeon-sonographer was noninferior to scintigraphy and may constitute a valid first-line imaging modality in patients with primary hyperparathyroidism, even without the addition of CEUS. Further imaging should be reserved for cases that are equivocal or nonlocalizing on ultrasonography.

Reduced fracture incidence in patients having surgery for primary hyperparathyroidism

OBJECTIVE

The indication of surgery in primary hyperparathyroidism has been controversial, as many patients experience mild disease. The primary aim was to evaluate fracture incidence in a contemporary population-based cohort of patients having surgery for primary hyperparathyroidism. The secondary aim was to investigate whether preoperative serum calcium, adenoma weight or multiglandular disease influence fracture incidence.

DESIGN

A retrospective cohort study with population controls. Primary outcomes, defined by discharge diagnoses and prescriptions, were any fracture and fragility fracture, secondary outcomes were multiple fractures anytime and osteoporosis. Subjects were followed 10 years pre- and up to 10 years postoperatively (or 31 December 2015). Multiple events per subject were allowed. Fracture incidence rate ratios (IRRs) for patients pre- and postoperatively were tabulated and evaluated with mixed-effects Poisson regression. Secondary outcomes were evaluated using conditional logistic regression.

PATIENTS

A Swedish nationwide cohort of patients having surgery for primary hyperparathyroidism (n = 5009) from the Scandinavian Quality Register for Thyroid, Parathyroid and Adrenal Surgery between 2003 and 2013 was matched with population controls (n = 14,983). Data were cross-linked with Statistics Sweden and the National Board of Health and Welfare.

MEASUREMENTS

Preoperative serum calcium and adenoma weight at pathological examination.

RESULTS

Patients had an increased incidence rate of any fracture preoperatively, IRR 1.27 (95% confidence interval: 1.11-1.46), highest in the last year before surgery. Fracture incidence was not increased postoperatively. Serum calcium, adenoma weight and multiglandular disease were not associated with fracture incidence.

CONCLUSIONS

Fracture incidence is higher in patients with primary hyperparathyroidism but is normalized after surgery.

The preoperative localisation of small parathyroid adenomas improves when adding Tc-99m-Sestamibi SPECT to multiphase contrast-enhanced CT

OBJECTIVES

To investigate the incremental value of Sestamibi SPECT combined with a non-enhanced and contrast-enhanced CT, using SPECT/CT, for the preoperative localisation of small parathyroid adenomas (PTA).

METHODS

Retrospectively, 147 patients surgically cured from primary hyperparathyroidism, as verified by biochemistry 6 months postoperatively, were included. All patients had preoperatively undergone a dual time ^99mTechnetium-Sestamibi SPECT (S) with multiphase CT including native (N), arterial (A) and venous (V) phases. Independently, two radiologists blinded from both the surgical and the preoperative imaging reports, sequentially performed PTA localisation starting with either [A] or [V], thereafter [A + N] or [V + N] and finally with the complete [A + N + S] or [V + N + S]. PTA localisation was reported for each image-set. The readers results were combined and the diagnostic performance for each image set was determined. Sensitivity was also calculated for the different quartiles of PTA weight distribution.

RESULTS

The median adenoma weight was 315 mg. No statistically significant differences in diagnostic performance between arterial and venous based image sets were found. The net effect of adding [N] was to increase specificity. Sestamibi SPECT significantly increased the overall diagnostic accuracy for arterial- and venous-based image sets, p = 0.0008 and p = 0.001, respectively. [A + N + S] was found to have the highest diagnostic performance with 86.5% sensitivity and 94.9% overall accuracy. [A + N + S] was particularly advantageous for locating PTA in the lower weight quartiles.

CONCLUSIONS

Native CT-phase and dual time point Sestamibi SPECT increase specificity and sensitivity, respectively. These, in combination with a single contrast-enhanced CT-phase is the most optimal examination protocol for preoperative localisation of PTA using SPECT/CT.

Mortality after surgery for primary hyperparathyroidism: results from a nationwide cohort

BACKGROUND

Contemporary patients with primary hyperparathyroidism are often diagnosed with mildly raised serum calcium levels. Previous studies have reported increased mortality in patients with primary hyperparathyroidism. This retrospective cohort study aimed to examine whether contemporary patients operated for primary hyperparathyroidism have higher mortality than the general population, and whether mortality in these patients is associated with serum calcium concentration, adenoma weight or multiglandular disease.

METHODS

Patients from a Swedish national cohort consisting of patients registered in the Scandinavian Quality Register for Thyroid, Parathyroid, and Adrenal Surgery 2003-2013, were matched with population controls. The National Patient Register, the Swedish Cause of Death Register, and socioeconomic data were cross-linked. End of follow-up was 10 years after surgery, 31 December 2015, or emigration. Mortality was analysed by standardized mortality ratio, Kaplan-Meier survival estimates, and univariable and multivariable Cox regression. Multiple imputation by chained equations was performed on missing data.

RESULTS

After exclusions, there were 5009 patients with primary hyperparathyroidism and 14 983 controls. Multivariable Cox regression analysis adjusted for age, sex, Charlson Co-morbidity Index, marital status, level of education, disposable income, and period of surgery showed lower mortality in patients than controls (hazard ratio (HR) 0.83, 95 per cent c.i. 0.75 to 0.92). In univariable Cox regression of mortality in patients, serum calcium concentration (mmoles per litre) was associated with mortality (HR 2.20, 1.53 to 3.16). This association remained in multivariable Cox regression after multiple imputation (HR 1.79, 1.19 to 2.70).

CONCLUSION

Mortality was not increased in patients operated for primary hyperparathyroidism compared with controls in a contemporary setting. Preoperative serum calcium concentration might, however, influence survival.

Could there be a role of serum zonulin increase in the development of hypercalcemia in primary hyperparathyroidism

PURPOSE

To evaluate the serum level of zonulin, which is an intestinal permeability (IP) biomarker, in primary hyperparathyroidism (PHPT) and to investigate the relationship between zonulin, calcium, and parathormone (PTH) levels.

METHODS

The study included 34 healthy control (HC) and 39 patients with PHPT. Serum calcium, phosphorus, magnesium, creatinine, albumin, and 24 h urine calcium levels were measured in all groups. Serum levels of zonulin were measured quantitatively by enzyme-linked immunosorbent assay (ELISA). Urinary ultrasonography (to assess the presence of nephrolithiasis) and dual energy X-ray absorptiometry (to assess the presence of osteoporosis) were used to evaluate complications related to PTHP.

RESULTS

Serum zonulin levels were significantly higher in the PHPT group than the HC group (p < 0.001). Zonulin levels were significantly positively correlated with plasma PTH and serum calcium levels (r = 0.600, p < 0.001 and r = 0.610, p < 0.001; respectively). There was no correlation between serum zonulin levels and adenoma volume.

CONCLUSION

Serum zonulin level increases in patients with PHPT. Serum zonulin levels show a moderate/strong positive correlation with serum calcium and plasma PTH levels. This suggests that IP increase may play a role in the development of hypercalcemia in patients with PHPT.

Dual Tracer 99mTc-Pertechnetate/99mTc-MIBI Dual-Time-Point SPECT/CT Parathyroid Gland Assessment Regarding to Parathyroid Gland Size and Biochemical Parameters - Two Years Single Imaging Centre Experience

INTRODUCTION

Preoperative parathyroid imaging is inevitable part of focused parathyroid surgery. The aim of our study was assessment of parathyroid scintigraphy diagnostic accuracy regarding to size and metabolic parameters of hyperfunctioning parathyroid tissue.

MATERIAL AND METHODS

Parathyroid scintigraphy for suspected primary hyperparathyroidism was performed in 95 patients during years 2015 and 2016. Of them, 75 patients with known clinical outcome (40 underwent surgery, 35 had documented laboratory follow-up) were further retrospectively evaluated. The performance of dual tracer 99mTc-pertechnetate and 99mTc-MIBI subtraction and dual-time-point 99mTc-MIBI imaging with SPECT/CT was analysed. Serum parathyroid hormone (PTH), calcaemia, ionized calcaemia and phosphataemia and ultrasound detected adenoma volume and largest diameter in false negative and true positive findings were compared using Mann-Whitney test.

RESULTS

Sensitivity and specificity of parathyroid scintigraphy was 74.5% and 95.8%, respectively. NPV was 63.8% and PPV 97.4%. Hyperfunctioning parathyroid tissue detectability was almost significantly associated with hypophosphataemia and PTH levels.

CONCLUSION

Parathyroid scintigraphy provides high sensitivity and superior specificity in parathyroid adenoma location, nevertheless the diagnostic accuracy tends to decline in smaller adenomas and in less metabolically active parathyroid tissue causing only subtle biochemical changes. 18F-Fluorocholine PET/CT or 3D SPECT/CT subtraction should be a reasonable option for those cases.

Predictors of multiglandular disease in primary hyperparathyroidism

Background

Primary hyperparathyroidism (pHPT) is caused by single- or multiglandular disease (MGD). Patients with MGD have an increased risk of complications at surgery and for persistence and recurrence after surgery. The study evaluated whether preoperative clinical and biochemical characteristics could predict MGD in patients with pHPT.

Methods

We retrospectively evaluated patients operated 1989–2013 for first-time, non-hereditary pHPT. MGD was defined in patients with more than one pathological gland excised at surgery or with persistent hypercalcemia after the excision of a single pathological parathyroid gland, confirmed by histopathology. Clinical and biochemical variables were compared in patients with single- and multiglandular disease. Logistic regression was used to identify variables predicting MGD, yielding odds ratios (OR) with 95% confidence intervals (CI).

Results

There were 707 patients, of which 79 (11%) had MGD. Patients with MGD were more likely to have negative sestamibi scintigraphy than patients with single-gland disease, 15 of 49 (31%) vs. 70 of 402 (17%; p = 0.03), to suffer from diabetes (12 of 74, 16%) vs. 45 out of 626 patients (7.2%; p < 0.01) and had lower preoperative levels of urinary calcium (3.80 vs. 4.44 mmol/L; p = 0.04). Multivariable analysis identified negative scintigraphy (OR 2.42; 95% CI 1.18 to 4.79), diabetes (OR 2.75; 95% CI 1.31 to 4.97) and elevated levels of osteocalcin (OR 3.79, 95% CI: 1.75 to 8.21) as predictors of MGD.

Conclusion

Negative sestamibi scintigraphy, diabetes and elevated osteocalcin levels were predictors of MGD.

SPECT/CT: an update on technological developments and clinical applications

Functional nuclear medicine imaging with single-photon emission CT (SPECT) in combination with anatomical CT has been commercially available since the beginning of this century. The combination of the two modalities has improved both the sensitivity and specificity of many clinical applications and CT in conjunction with SPECT that allows for spatial overlay of the SPECT data on good anatomy images. Introduction of diagnostic CT units as part of the SPECT/CT system has also potentially allowed for a more cost-efficient use of the equipment. Most of the SPECT systems available are based on the well-known Anger camera principle with NaI(Tl) as a scintillation material, parallel-hole collimators and multiple photomultiplier tubes, which, from the centroid of the scintillation light, determine the position of an event. Recently, solid-state detectors using cadmium-zinc-telluride became available and clinical SPECT cameras employing multiple pinhole collimators have been developed and introduced in the market. However, even if new systems become available with better hardware, the SPECT reconstruction will still be affected by photon attenuation and scatter and collimator response. Compensation for these effects is needed even for qualitative studies to avoid artefacts leading to false positives. This review highlights the recent progress for both new SPECT cameras systems as well as for various data-processing and compensation methods.

Incidence of parathyroid disorders in Indian adult male population: A 25-year follow-up study

CONTEXT AND OBJECTIVE

Detailed information on the epidemiology of parathyroid disorders in India is lacking. Most of the available data pertain to primary hyperparathyroidism (PHPT) rather than the overall burden of parathyroid disorders. We studied the incidence of parathyroid disorders in a cohort of service personnel followed for a long duration.

DESIGN, SETTING AND PATIENTS

The data for this retrospective, descriptive epidemiological study were derived from the electronic medical records (EMR) of health care personnel enrolled between 1990 and 2015. Subjects were recruited between the ages of 17 and 20 years in good health, and the data pertaining to parathyroid disorders were derived from the EMR.

MAIN OUTCOMES MEASURES

We calculated the incidence rates per person-years of parathyroid disorders using appropriate statistical methods.

RESULTS

Our analysis includes 51 217 participants (median age 33, range 17-54 years) with a mean follow-up of 12.5 years. Yearly evaluation of the data gave cumulative follow-up duration of 613 925 person-years. PHPT was diagnosed in 37 patients and hypoparathyroidism in 16 patients, giving incidence rates of 6 and 2.6 per 100 000 person-years, respectively. Only one patient was diagnosed with pseudohypoparathyroidism (0.16 per 100 000 person-years). Of the 37 patients with PHPT, 16 (43%) developed postsurgical hypoparathyroidism.

CONCLUSIONS

Our cohort had a low incidence of PHPT when compared to Western populations. Long-term epidemiological studies are essential to identify the demographic trends of metabolic bone disorders in India.

Impaired calcium sensing distinguishes primary hyperparathyroidism (PHPT) patients with low bone mineral density

CONTEXT

A subset of PHPT patients exhibit a more severe disease phenotype characterized by bone loss, fractures, recurrent nephrolithiasis, and other dysfunctions, but the underlying reasons for this disparity in clinical presentation remain unknown.

OBJECTIVE

We sought to identify new mechanistic indices that could inform more personalized management of PHPT.

DESIGN

Pre-, peri-, and postoperative data and demographic, clinical, and pathological information from patients undergoing parathyroidectomy for PHPT were collected. Univariate and partial Spearman correlation was used to estimate the association of parathyroid tumor calcium sensing capacity with select variables.

PATIENTS OR OTHER PARTICIPANTS

An unselected series of 237 patients aged >18years and undergoing parathyroidectomy for PHPT were enrolled.

MAIN OUTCOME MEASURES

Calcium sensing capacity, expressed as the concentration required for half-maximal biochemical response (EC50), was evaluated in parathyroid tumors from an unselected series of 74 patients and assessed for association with clinical parameters. The hypothesis was that greater disease severity would be associated with attenuated calcium sensitivity and biochemically autonomous parathyroid tumor behavior.

RESULTS

Parathyroid tumors segregated into two distinct groups of calcium responsiveness (EC50<3.0 and ≥3.0mM). The low EC50 group (n=27) demonstrated a mean calcium EC50 value of 2.49mM [95% confidence interval (CI): 2.43-2.54mM], consistent with reference normal activity. In contrast, the high EC50 group (n=47) displayed attenuated calcium sensitivity with a mean EC50 value of 3.48mM [95% CI: 3.41-3.55mM]. Retrospective analysis of the clinical registry data suggested that high calcium EC50 patients presented with a more significant preoperative bone mineral density (BMD) deficit with a t-score of -2.7, (95% CI: -3.4 to -1.9) versus 0.9, (95% CI: -2.1 to -0.4) in low EC50 patients (p<0.001). After adjusting for gender, age, BMI, 25 OH vitamin D level and preoperative iPTH, lowest t-score and calcium EC50 were inversely correlated, with a partial Spearman correlation coefficient of -0.35 (p=0.02).

CONCLUSIONS

Impaired calcium sensing in parathyroid tumors is selectively observed in a subset of patients with more severe bone mineral density deficit. Assessment of parathyroid tumor biochemical behavior may be a useful predictor of disease severity as measured by bone mineral density in patients with PHPT.

THE VOLUME OF SOLITARY PARATHYROID ADENOMA IS RELATED TO PREOPERATIVE PTH AND 25OH-D3, BUT NOT TO CALCIUM LEVELS

Purpose

To correlate the volume of parathyroid adenomas with the hormonal and metabolic profile at patients diagnosed with primary hyperparathyroidism (pHPTH).

Patients and Methods

Cross-sectional multicentric study, enrolling 52 patients with pHPTH from two medical institutions. Serum calcium and PTH were evaluated in all patients before surgery, whereas 25OHD3 was measured only in the 33 patients recruited form one medical unit. The volume of parathyroid adenoma was measured by using the formula of a rotating ellipsoid.

Results

We observed a significant correlation of the volume of parathyroid adenomas with PTH at patients from the two units and in the whole group (p < 0.0001), but not with serum calcium (p = 0.494). Twenty-five out of the 33 patients at whom 25OHD3 was measured had levels in the range of deficiency. 25OHD3 was not correlated with PTH or calcium levels, but was negatively correlated to the adenoma volume and positively to the PTH/volume ratio (p = 0.041 and p = 0.048, respectively).

Conclusions

The volume of parathyroid adenoma seems to be related to preoperative PTH and 25OHD3, but not to calcium level. Vitamin D deficiency is frequently found at patients with pHPTH and may contribute to particular disease profiles, including larger parathyroid adenomas.

A meta-analysis comparing the biochemistry of primary hyperparathyroidism in youths to the biochemistry of primary hyperparathyroidism in adults

CONTEXT

The distinctive presentation of primary hyperparathyroidism (PHPT) in adults and youths suggest that PHPT is a fundamentally different disease in these two groups.

OBJECTIVE

To understand the difference in PHPT between adults and youths we compared the biochemistry of PHPT in these two groups.

DESIGN

This study is a systematic review and meta-analysis of retrospective studies published 1966-2014 on PHPT.

DATA SOURCES

All studies were obtained through Medline (1966-2014).

STUDY SELECTION AND DATA EXTRACTION

Only studies that included post-surgical subjects and that explicitly described biochemical results from more than one decade were included. Data were extracted from each article to generate the mean and SE for multiple biochemical parameters.

DATA SYNTHESIS

We analyzed 16 studies describing 268 unique youths and 2405 adults with PHPT. Youths with PHPT had significantly (P < .05) greater serum and urinary calcium than adults with PHPT (3.2 ± 0.1 mmol/L vs 2.8 ± 0.0 mmol/L for serum calcium, and 9.95 ± 1.26 mmol/d vs 7.15 ± 0.56 mmol/d for urine calcium, [mean ± SEM]). There were no significant differences in serum intact PTH, phosphorus, or alkaline phosphatase.

CONCLUSIONS

Juvenile PHPT has greater hypercalcemia and hypercalciuria than adult PHPT at similar concentrations of serum intact PTH. These observations suggest that there are differences in the pathophysiology of PHPT between juvenile and adult patients who reflect an apparent decrease in the sensitivity of the parathyroid adenoma to negative feedback by calcium and increased sensitivity of target tissues to the effects of PTH.

Primary hyperparathyroidism in children and adolescents

Primary hyperparathyroidism (PHPT) is a common endocrine disorder in adults in whom the typical presentation is incidentally discovered as asymptomatic hypercalcemia. PHPT is much less common in children and adolescents, but has greater morbidity in this age group, as most young patients with PHPT will have symptomatic hypercalcemia or complications such as kidney stones, abdominal pain, and skeletal fragility. An important feature of PHPT in younger patients is the relatively high prevalence of germline inactivating mutations of the CASR gene, which encodes the calcium-sensing receptor. Biallelic CASR mutations cause neonatal severe hyperparathyroidism, a life-threatening condition that presents within days of life with marked hypercalcemia, respiratory distress, failure to thrive, and skeletal demineralization. By contrast, more common heterozygous CASR mutations are generally associated with a benign variant of PHPT termed familial hypocalciuric hypercalcemia. Appropriate management of PHPT in children and adolescents requires distinction between familial hypocalciuric hypercalcemia, which generally requires no specific treatment, and other forms of PHPT that are best treated by parathyroidectomy.

Genetic characterization of large parathyroid adenomas

In this study, we genetically characterized parathyroid adenomas with large glandular weights, for which independent observations suggest pronounced clinical manifestations. Large parathyroid adenomas (LPTAs) were defined as the 5% largest sporadic parathyroid adenomas identified among the 590 cases operated in our institution during 2005-2009. The LPTA group showed a higher relative number of male cases and significantly higher levels of total plasma and ionized serum calcium (P<0.001). Further analysis of 21 LPTAs revealed low MIB1 proliferation index (0.1-1.5%), MEN1 mutations in five cases, and one HRPT2 (CDC73) mutation. Total or partial loss of parafibromin expression was observed in ten tumors, two of which also showed loss of APC expression. Using array CGH, we demonstrated recurrent copy number alterations most frequently involving loss in 1p (29%), gain in 5 (38%), and loss in 11q (33%). Totally, 21 minimal overlapping regions were defined for losses in 1p, 7q, 9p, 11, and 15q and gains in 3q, 5, 7p, 8p, 16q, 17p, and 19q. In addition, 12 tumors showed gross alterations of entire or almost entire chromosomes most frequently gain of 5 and loss of chromosome 11. While gain of 5 was the most frequent alteration observed in LPTAs, it was only detected in a small proportion (4/58 cases, 7%) of parathyroid adenomas. A significant positive correlation was observed between parathyroid hormone level and total copy number gain (r=0.48, P=0.031). These results support that LPTAs represent a group of patients with pronounced parathyroid hyperfunction and associated with specific genomic features.

Normal PTH levels in primary hyperparathyroidism: still the same disease?

PURPOSE

Previous studies have suggested that primary hyperparathyroidism (pHPT) with only normal parathyroid hormone (PTH) levels is a milder, less symptomatic form of pHPT. This study investigates symptoms, laboratory values, imaging, and outcomes of sporadic pHPT patients with normal PTH values.

METHODS

We reviewed our prospectively collected database of 861 patients with sporadic pHPT who underwent parathyroidectomy between December 1999 and June 2010. Patients with only normal PTH values for 6 months before surgery were compared to a randomized control group of sporadic pHPT patients with elevated PTH, matched 1:2 for age and gender.

RESULTS

Fifty-eight (7%) patients had only normal PTH values within 6 months of surgery. The mean PTH was 55.1 pg/ml in the normal PTH group and 151.3 pg/ml in the control group (n=116). There was no difference in preoperative calcium values, subjective symptoms, bone health, or the frequency of single-gland disease (SGD; 88% vs. 91%) between the two groups, but the normal PTH group had higher preoperative vitamin D values (30.8 vs. 21.4 ng/ml; P<0.001), smaller adenomas (405 vs. 978 mg, P<0.001), and more frequently underwent bilateral neck exploration (57% vs. 49%). There was a trend toward lower sensitivity of preoperative imaging in the normal PTH group.

CONCLUSIONS

Patients with pHPT and either elevated or normal PTH levels present with similar symptoms and calcium levels. The majority of patients with normal PTH have SGD, although adenomas are smaller. This may explain why patients with normal PTH values have less sensitive imaging and more frequently require four-gland exploration.