Genetic testing for hereditary hyperparathyroidism and familial hypocalciuric hypercalcaemia in a large UK cohort

BACKGROUND

Primary hyperparathyroidism (PHPTH) is a common endocrine disorder and an estimated 10% of cases are hereditary, related to syndromes including; multiple endocrine neoplasia (MEN) type 1, MEN type 4, MEN2A and hereditary hyperparathyroidism-jaw tumour syndrome. Establishing the underlying genetic cause for PHPTH allows for personalized and cost-effective management. Familial hypocalicuric hypercalcaemia (FHH) is a benign disorder of hypercalcaemia associated with an inappropriately low urinary calcium excretion, which is quantified by the calcium creatinine clearance ratio (CCCR). Recent NHS England National Genomic Test Directory testing criteria for familial hyperparathyroidism state testing patients presenting with PHPTH and CCCR > 0.02 presenting (i) <35 years of age, or (ii) <45y with one of (a) multiglandular disease, or (b) hyperplasia on histology, or (c) ossifying fibroma(s) of the maxilla and/ or mandible, or (d) a family history of unexplained PHPTH. The testing criterion for FHH is a CCCR < 0.02.

AIMS AND METHODS

A retrospective review of patients referred for genetic testing over a 4 year period for suspected hereditary HPTH was performed. Genetic analysis was performed by next-generation sequencing of the following genes; MEN1, CDC73, CASR, CDKN1A, CDKN1B, CDKN2B, CDKN2C, RET, GCM2, GNA11, and AP2S1 in NHS-accredited Regional Genetic laboratories. Aims of this study were to better define testing criteria for suspected hereditary PHPTH in a UK cohort.

RESULTS

A total of 121 patients were included in this study (92 female) with a mean age of 41 years (SD 17). A pathogenic germline variant was identified in 16% (n = 19). A pathogenic variant was identified in the PHPTH genes CDC73 in a single patient and MEN1 in six patients (6% of total), in the FHH genes, CASR in 11 patients and AP2S1 in a single paediatric case (10% of total). A variant of uncertain significance (VUS) was identified in eight patients (6%) but over the course of this study familial segregation studies and computational analysis enabled re-classification of four of the variants, with two VUS's in the CASR gene being upgraded to likely pathogenic variants. Age at diagnosis and multiglandular disease as sole risk factors were not predictive of a pathogenic germline variant in this cohort but a positive family history was strongly predictive (P = .0002). A significant difference in the mean calcium creatinine clearance ratio (CCCR) in those patients with an identified CASR pathogenic variant versus those without (P = .0001) was demonstrated in this study. Thirty-three patients were aged over 50 years and the diagnostic rate of a pathogenic variant was 15.1% in those patients >50 years of age compared to 15.9% in those <50 years. Five patients >50 years and with a CCCR of <0.01, were diagnosed with a pathogenic variant in CASR.

CONCLUSION

Family history was the strongest predictor of hereditary PHPTH in this cohort. This study has highlighted the importance of re-evaluating VUS's in order to inform patient management and enable appropriate genetic counselling. Finally, this study has demonstrated the need to consider genetic testing for PHPTH in patients of any age, particularly those with additional risk factors.

Diagnosis and Management of Primary Hyperparathyroidism Across the Veterans Affairs Health Care System

IMPORTANCE

Untreated primary hyperparathyroidism impairs quality of life and incurs substantial costs. Parathyroidectomy is a low-risk, high-success, definitive intervention.

OBJECTIVES

To determine the appropriateness of diagnostic evaluation for primary hyperparathyroidism in patients with hypercalcemia and the use of parathyroidectomy for the treatment of primary hyperparathyroidism across the Veterans Affairs (VA) health care system.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort study of veterans with hypercalcemia and primary hyperparathyroidism was conducted from January 1, 2000, through September 30, 2015, using the VA Corporate Data Warehouse, a national electronic health record-based repository. The study included 371 370 veterans with chronic hypercalcemia and 47 158 veterans with biochemical evidence of primary hyperparathyroidism diagnosed by hypercalcemia, elevated serum parathyroid hormone levels, and near-normal serum creatinine levels. Statistical analysis was performed from April 21, 2017, to April 10, 2019.

MAIN OUTCOMES AND MEASURES

The proportion of veterans with hypercalcemia who have parathyroid hormone levels evaluated, the proportion of veterans with hyperparathyroidism who are treated surgically, and the factors associated with parathyroidectomy using generalized linear latent and mixed model regression.

RESULTS

Of 371 370 patients with chronic hypercalcemia, 86 887 (23.4%) received further testing with parathyroid hormone level. Of 47 158 patients meeting diagnostic criteria for primary hyperparathyroidism (42 737 men [90.6%] and 4421 women [9.4%]; mean [SD] age, 67.3 [11.8] years), 6048 (12.8%) underwent parathyroidectomy. Of 5793 patients with primary hyperparathyroidism presenting with a serum calcium level more than 1 mg/dL above the upper limit of normal, 1501 (25.9%) underwent parathyroidectomy. There was a decreasing trend in the use of parathyroidectomy over time. Factors positively associated with parathyroidectomy were nephrolithiasis (odds ratio [OR], 2.23; 95% CI, 1.90-2.61) and non-Hispanic white race/ethnicity (OR, 1.31; 95% CI, 1.17-1.46), while age (OR, 0.95; 95% CI, 0.95-0.96), Elixhauser Comorbidity Index score (OR, 0.76; 95% CI, 0.72-0.80), decreased estimated glomerular filtration rate (OR, 0.52; 95% CI, 0.45-0.60), and diagnosis of osteoporosis (OR, 0.65; 95% CI, 0.52-0.80) were inversely related to surgery.

CONCLUSIONS AND RELEVANCE

From this study's findings, parathyroid hormone level is infrequently tested in patients with hypercalcemia, suggesting underdiagnosis of primary hyperparathyroidism. Patients meeting diagnostic criteria for primary hyperparathyroidism are undertreated with recommended parathyroidectomy. Similar gaps have previously been observed in non-VA care of primary hyperparathyroidism, suggesting the need for a systematic evaluation of barriers to diagnosis and treatment that informs intervention design.

Why Is Hyperparathyroidism Underdiagnosed and Undertreated in Older Adults?

Introduction

Hyperparathyroidism significantly decreases quality of life, yet elderly patients are underdiagnosed and undertreated even though parathyroidectomy offers definitive cure with minimal morbidity. The purpose of this study is to determine why older patients with hyperparathyroidism are not appropriately diagnosed and referred for parathyroidectomy.

Methods

We reviewed charts for a random sample of 25 patients aged 75 and older who had hyperparathyroidism and were referred for surgical evaluation, and 25 who were not referred. Two reviewers independently evaluated medical records to identify reasons for delayed diagnosis of hyperparathyroidism and reasons for nonreferral for parathyroidectomy.

Results

The median age of our cohort was 84 (80-96) years, 90% were women, 60% were white, and median follow-up was 5.5 (1-17) years. In 58% of all patients, an elevated serum calcium was not acknowledged. Even when calcium and parathyroid hormone levels were both elevated, the diagnosis was missed in 28% of patients, and 16% with clear symptoms of hyperparathyroidism remained undiagnosed. For 42% of patients, a nonsurgeon informed them that surgery offered no benefit. Surgery was also rejected as a treatment for 36% of patients despite the development of new symptoms or rising calcium.

Conclusions

Substantial gaps exist in processes for diagnosis and referral of patients with hyperparathyroidism that lead to underdiagnosis and undertreatment. To improve rates of diagnosis and treatment, strategies are needed to educate nonsurgeons and patients about the benefits of surgery and to modify care processes to more efficiently diagnose and refer patients.

Failure to Diagnose Hyperparathyroidism in 10,432 Patients With Hypercalcemia: Opportunities for System-level Intervention to Increase Surgical Referrals and Cure

OBJECTIVE

To determine whether a significant number of patients with hyperparathyroidism remain undiagnosed and untreated.

BACKGROUND

Failure to diagnose primary hyperparathyroidism and refer patients to surgeons leads to impaired quality of life and increased costs. We hypothesized that many patients with hyperparathyroidism would be untreated due to not considering the diagnosis, inadequate evaluation of hypercalcemia, and under-referral to surgeons.

METHODS

We reviewed administrative data on 682,704 patients from a tertiary referral center between 2011 and 2015, and identified hypercalcemia (>10.5 mg/dL) in 10,432 patients. We evaluated whether hypercalcemic patients underwent measurement of parathyroid hormone (PTH), had documentation of hypercalcemia/hyperparathyroidism, or were referred to surgeons.

RESULTS

The mean age of our cohort was 54 years, with 61% females, and 56% whites. Only 3200 (31%) hypercalcemic patients had PTH levels measured, 2914 (28%) had a documented diagnosis of hypercalcemia, and 880 (8%) had a diagnosis of hyperparathyroidism in the medical record. Only 592 (22%) out of 2666 patients with classic hyperparathyroidism (abnormal calcium and PTH) were referred to surgeons.

CONCLUSIONS

A significant proportion of patients with hyperparathyroidism do not undergo appropriate evaluation and surgical referral. System-level interventions which prompt further evaluation of hypercalcemia and raise physician awareness about hyperparathyroidism could improve outcomes and produce long-term cost savings.

Management of Primary Hyperparathyroidism: Can We Do Better?

The failure to follow national guidelines in management of various diseases has been previously established. We sought to quantify primary care providers’ familiarity with primary hyperparathyroidism as it affects adherence to the 2009 National Institute of Health (NIH) consensus recommendations in treatment of primary hyperparathyroidism. A large primary care group was surveyed to determine their familiarity with the 2009 NIH consensus recommendations for management of primary hyperparathyroidism (PHPT). Retrospective review of the group's records (2009–2011) was performed to verify compliance. Survey responders included 109 clinicians, 31 per cent were familiar with all criteria for surgical intervention in asymptomatic patients and 34 per cent correctly identified appropriate surveillance testing for patients undergoing observation. Chart review identified 124 patients with PHPT. Of the patients who met NIH criteria, 34 per cent had a parathyroidectomy. Younger age, higher intact parathyroid hormone, hypercalciuria, and history of nephrolithiasis were associated with surgery in multivariable analysis. Of the observed patients, 16 per cent had appropriate surveillance studies. In conclusion, this study confirms suboptimal adherence with consensus recommendations in management of PHPT. A minority of clinicians demonstrated solid familiarity with management strategies, paralleling their treatment approach. Educational efforts may improve adherence with upcoming national recommendations.

Genetics of parathyroid tumours

Primary hyperparathyroidism (PHPT), due to parathyroid tumours, may occur as part of a complex syndrome or as an isolated (nonsyndromic) disorder, and both forms can occur as familial (i.e. hereditary) or nonfamilial (i.e. sporadic) disease. Syndromic PHPT includes multiple endocrine neoplasia (MEN) types 1 to 4 (MEN1 to MEN4) and the hyperparathyroidism-jaw tumour (HPT-JT) syndrome. Syndromic and hereditary PHPT are often associated with multiple parathyroid tumours, in contrast to sporadic PHPT, in which single parathyroid adenomas are more common. In addition, parathyroid carcinomas may occur in ~15% of patients with the HPT-JT syndrome. MEN1 is caused by abnormalities of the MEN1 gene which encodes a tumour suppressor; MEN2 and MEN3 are due to mutations of the rearranged during transfection (RET) proto-oncogene, which encodes a tyrosine kinase receptor; MEN4 is due to mutations of a cyclin-dependent kinase inhibitor (CDNK1B); and HPT-JT is due to mutations of cell division cycle 73 (CDC73), which encodes parafibromin. Nonsyndromic PHPT, which may be hereditary and referred to as familial isolated hyperparathyroidism, may also be due to MEN1, CDC73 or calcium-sensing receptor (CASR) mutations. In addition, ~10% of patients presenting below the age of 45 years with nonsyndromic, sporadic PHPT may have MEN1, CDC73 or CASR mutations, and overall more than 10% of patients with PHPT will have a mutation in one of 11 genes. Genetic testing is available and of value in the clinical setting, as it helps in making the correct diagnosis and planning the management of these complex disorders associated with parathyroid tumours.

Percutaneous Ultrasound-Guided Laser Ablation with Contrast-Enhanced Ultrasonography for Hyperfunctioning Parathyroid Adenoma: A Preliminary Case Series

The study was to evaluate the safety and effectiveness of ultrasound-guided percutaneous laser ablation (pLA) as a nonsurgical treatment for primary parathyroid adenoma. Surgery was contraindicated in, or refused by, the included patients. No lesion enhancement on contrast-enhanced ultrasound immediately after pLA was considered "complete ablation." Nodule size, serum calcium, and parathyroid hormone level were compared before and after pLA. Complete ablation was achieved in all 21 patients with 1 (n = 20) or 2 (n = 1) sessions. Nodule volume decreased from 0.93 ± 0.58 mL at baseline to 0.53 ± 0.38 and 0.48 ± 0.34 mL at 6 and 12 months after pLA (P < 0.05). At 1 day, 6 months, and 12 months after pLA, serum PTH decreased from 15.23 ± 3.00 pmol/L at baseline to 7.41 ± 2.79, 6.95 ± 1.78, and 6.90 ± 1.46 pmol/L, serum calcium decreased from 3.77 ± 0.77 mmol/L at baseline to 2.50 ± 0.72, 2.41 ± 0.37, and 2.28 ± 0.26 mmol/L, respectively (P < 0.05). At 12 months, treatment success (normalization of PTH and serum calcium) was achieved in 81%. No serious complications were observed. Ultrasound-guided pLA with contrast-enhanced ultrasound is a viable alternative to surgery for primary parathyroid adenoma.