Clinical aspects of hyperparathyroidism in Japanese multiple endocrine neoplasia type 1

[Predicting the presence of MEN1 gene mutation based on the clinical phenotype of patients with primary hyperparathyroidism]

BACKGROUND

Timely referral of patients for genetic testing to rule out MEN1-associated primary PHPT is important factor in determining treatment strategy and prognosis. In the context of the limited availability of genetic testing, the search for clinical markers indicative of MEN1 gene mutations remains an extremely relevant task.

AIM

To determine the diagnostic value of clinical features of primary PHPT in young patients for predicting the presence of MEN1 gene mutations.

MATERIALS AND METHODS

A single-center, prospective study was conducted at the Endocrinology Research Centre, involving 273 patients with PHPT in the period 2015-2022. Based on the results of genetic and laboratory tests, patients were divided into three groups: those with MEN1 gene mutations (MEN+ group, n=71), those without MEN1 gene mutations - isolated sporadic PHPT (MEN- group, n=158), and patients with PHPT and associated endocrine gland disorders - MEN-1 syndrome phenocopies (PHEN group, n=32). Subgroups of patients younger than 40 years of age were also identified. Comparative analysis was performed among the independent groups and subgroups, and logistic regression analysis was used to develop a mathematical model for predicting the probability of the presence of MEN1 gene mutation.

RESULTS

Patients in the MEN+ and MEN- groups were comparable by gender and age at manifestation, as well as calcium-phosphorus metabolism parameters and PHPT complications. In the PHEN group, PHPT manifested at older age compared to the other groups (p<0.001 for all), with lower total calcium levels and a trend toward lower iPTH concentrations. The MEN+ group had a significantly higher frequency of multiglandular parathyroid (PG) involvement, PHPT recurrence, and positive family history compared to the MEN- and PHEN groups. Histologically, adenomas predominated in the PHEN and MEN- groups (92% and 94%, respectively), whereas hyperplasia of PGs were more common in the MEN+ group (49%). None of the PHEN patients had all three «classic» components of the MEN-1 syndrome, and the clinical course of PHPT was similar to that of the MEN- group. These differences were also observed in the subgroups of patients younger than 40 years, which formed the basis for the development of a mathematical model. The logistic regression equation for predicting the probability of the presence of the MEN1 gene mutation included eight predictors, with a diagnostic sensitivity of 96% and specificity of 98%.

CONCLUSION

Based on the analysis performed, eight hereditary predictors of PHPT within the MEN-1 syndrome were identified. A mathematical model was developed to predict the presence of the MEN1 gene mutation in patients, which demonstrated high classification performance on the training dataset. Further refinement of the model will help improve the quality of medical care for patients with PHPT.

Multiple endocrine neoplasia type 1 revealed by a hip pathologic fracture

Multiple endocrine neoplasia type 1 is a rare autosomal inherited syndrome that affects a variety of endocrine tissues such as the parathyroid, endocrine pancreas, and anterior pituitary. Osseous complications are often misdiagnosed. We presented a case of a 46-year-old woman with pathological fractures of the lower limb. She had a history of type 1 diabetes and galactorrhea. Laboratory examinations showed hypercalcemia and an increased level of parathyroid hormone related to hyperparathyroidism. Serum chromogranin A level was increased at 9369 ng/mL (N < 102). A somatostatin receptor scintigraphy (octreoscan) revealed pathological uptake in the gastric wall, later cave adenopathy, and liver. The diagnosis of multiple endocrine neoplasia type 1 was made based on radiological and histological findings. The patient underwent a subtotal parathyroidectomy associated with somatostatin analog treatment leading to significant improvement. A literature review was conducted by searching PubMed using these following terms: multiple endocrine neoplasia type 1, hyperparathyroidism, fracture, menin, osteoporosis. We emphasized bone involvement related to multiple endocrine neoplasia type 1 syndrome. This diagnosis should be considered when pathological fractures occur in young patients with a history of endocrine disorder. We highlighted the importance of imaging features in making the diagnosis of multiple endocrine neoplasia type 1. Early management of this disease is necessary. Treatment including parathyroidectomy and somatostatin analogs leads to bone preservation and functional improvement.

Differences between sporadic and MEN related primary hyperparathyroidism; clinical expression, preoperative workup, operative strategy and follow-up

Background

Primary hyperparathyroidism (PHPT) is most commonly sporadic (sPHPT). However, sometimes PHPT develops as part of multiple endocrine neoplasia (MEN) type 1 or 2A. In all, parathyroidectomy is the only curative treatment. Nevertheless, there are important differences in clinical expression and treatment.

Methods

We analyzed a consecutive cohort of patients treated for sporadic, MEN1-related, and MEN2A-related PHPT and compared them regarding clinical and biochemical parameters, differences in preoperative workup, operative strategies, findings, and outcome.

Results

A total of 467 patients with sPHPT, 52 with MEN1- and 16 with MEN2A-related PHPT were analyzed. Patients with sPHPT were older, more often female and had higher preoperative calcium and parathyroid hormone levels, when compared with MEN1 and MEN2A patients. Minimally invasive parathyroidectomy (MIP) was performed in 367 of 467 sPHPT patients (79%). One abnormal parathyroid was found in 426 patients (91%). Two or more in 35 patients (7%). In six patients (1%) no abnormal parathyroid gland was retrieved. Of 52 MEN1 patients, eight (15%) underwent a MIP and 44 patients (85%) underwent conventional neck exploration (CNE); with resection of fewer than 3½ enlarged glands in 21 patients (40%), subtotal parathyroidectomy (SPTX, 3-3½ glands) in seventeen (33%) and total parathyroidectomy with autotransplantation (TPTX) in six (12%). Eleven patients (21%) had persistent disease, 29 (56%) recurrent PHPT and nine (17%) permanent hypoparathyroidism, mostly after TPTX. Of 16 MEN2A patients, six (38%) underwent MIP, four (25%) CNE and six (38%) selective resection of the enlarged gland(s) during total thyroidectomy. Three patients (19%) suffered from persistent PHPT and two (13%) developed recurrent disease.

Conclusions

Sporadic PHPT, MEN1- and MEN2A-related PHPT are three distinct entities as is reflected preoperatively by differences in gender, age at diagnosis and calcium and PTH levels.

MEN2A patients are very similar to sPHPT with respect to operative approach and findings. MIP is the treatment of choice for both. MIP has low rates of persistent and recurrent PHPT and a low complication rate. The percentage of multiglandular disease and recurrences are significantly higher in MEN1 patients, demonstrating the need for a different approach. We advocate treating these patients with CNE and SPTX.

Biochemical, bone and renal patterns in hyperparathyroidism associated with multiple endocrine neoplasia type 1

Primary hyperparathyroidism associated with multiple endocrine neoplasia type I (hyperparathyroidism/multiple endocrine neoplasia type 1) differs in many aspects from sporadic hyperparathyroidism, which is the most frequently occurring form of hyperparathyroidism. Bone mineral density has frequently been studied in sporadic hyperparathyroidism but it has very rarely been examined in cases of hyperparathyroidism/multiple endocrine neoplasia type 1. Cortical bone mineral density in hyperparathyroidism/multiple endocrine neoplasia type 1 cases has only recently been examined, and early, severe and frequent bone mineral losses have been documented at this site. Early bone mineral losses are highly prevalent in the trabecular bone of patients with hyperparathyroidism/multiple endocrine neoplasia type 1. In summary, bone mineral disease in multiple endocrine neoplasia type 1 related hyperparathyroidism is an early, frequent and severe disturbance, occurring in both the cortical and trabecular bones. In addition, renal complications secondary to sporadic hyperparathyroidism are often studied, but very little work has been done on this issue in hyperparathyroidism/multiple endocrine neoplasia type 1. It has been recently verified that early, frequent, and severe renal lesions occur in patients with hyperparathyroidism/multiple endocrine neoplasia type 1, which may lead to increased morbidity and mortality. In this article we review the few available studies on bone mineral and renal disturbances in the setting of hyperparathyroidism/multiple endocrine neoplasia type 1. We performed a meta-analysis of the available data on bone mineral and renal disease in cases of multiple endocrine neoplasia type 1-related hyperparathyroidism.

Effects of teriparatide on serum calcium in postmenopausal women with osteoporosis previously treated with raloxifene or alendronate

The effect of teriparatide (20 microg/day) on serum calcium was examined in postmenopausal women previously treated with alendronate or raloxifene. Women previously treated with alendronate or raloxifene who added teriparatide or switched to teriparatide did not have clinically meaningful increases in mean predose serum calcium.

INTRODUCTION

The effects of a 6-month treatment with teriparatide (20 microg/day; rhPTH(1-34), TPTD) on serum calcium (Ca) was examined in a prospective study of postmenopausal women previously treated with alendronate (70 mg/week or 10 mg/day [ALN] or raloxifene 60 mg/d [RLX]) for > or =18 months.

METHODS

Women continued their usual ALN or RLX during a 2-month antiresorptive phase. Women previously treated with ALN were randomized to add TPTD (n = 52) or switch to TPTD (n = 50) and women previously treated with RLX were randomized to add TPTD (n = 47) or switch to TPTD (n = 49). All were to take at least 500 mg/day of elemental Ca and 400-800 IU/day of vitamin D.

RESULTS

Predose mean serum Ca did not significantly change in groups adding TPTD to either RLX or ALN treatment. In patients who switched from RLX or ALN to TPTD, mean serum Ca increased by 0.05 mmol/L and 0.04 mmol/L respectively. Only 1 patient had the predefined calcium endpoint of serum calcium > 2.76 mmol/L (11 mg/dL) at more than one visit.

CONCLUSIONS

Women previously treated with ALN or RLX who added TPTD or switched to TPTD did not have clinically meaningful increases in mean predose serum Ca.

Tumours of familial origin in the head and neck

Individuals with inherited cancer syndromes are at significant risk of developing both benign and malignant tumours as a result of a germline mutation in a specific tumour suppressor gene. Tumours of familial origin are a rare event in the head and neck but despite this, they deserve a growing interest. Familial paragangliomas are most of the time limited to the paraganglionar system, but also may be part of different syndromic associations. Since early detection of paragangliomas reduces the incidence of morbidity and mortality, genotypic analysis in the search of SDHB, SDHC and SDHD mutations in families of affected patients plays a front-line diagnostic role, leading to more efficient patient management. Multiple endocrine neoplasias type 1 are characterized by the simultaneous occurrence of at least two of the three main related endocrine tumours: parathyroid, enteropancreatic and anterior pituitary. These tumours arise from inactivating germline mutations in the MEN-1 gene. No clear correlation of MEN-1 genotype with genotype has emerged to date, and MEN-1 mutation testing in tumours is not used clinically because it have not implications for tumour staging. Multiple endocrine neoplasia type 2 is due to a germline mutation in the RET proto-oncogene. Hallmarks of MEN-2A (the commonest phenotypic variant) include medullary thyroid carcinoma, pheochromocytoma, and hyperparathyroidism. The most central clinical difference with MEN-1 is that the associated cancer can be prevented or cured by early thyroidectomy in mutation carriers. Individuals with neurofibomatosis type 1 present early in life with pigmentary abnormalities, skinfold freckling and iris hamartomas, as result of NF1 gene mutation. Neurofibromatosis 2 is caused by inactivating mutations of the NF2 gene, and is characterized by the development of nervous system tumours (mainly bilateral vestibular schwannomas), ocular abnormalities, and skin tumours. The molecular genetic basis of nasopharyngeal carcinomas remains unknown, but there is evidence for the linkage of these tumours to chromosome 3p. Finally, the high rate of p16 mutations in squamous cell carcinomas and the association of p16 with familial melanoma propose p16 as an ideal candidate gene predisposing to familial squamous cell carcinomas. The elucidation of the cellular processes affected by dysfunction in familial tumours of the head and neck may serve to identify potential targets for future therapeutic interventions.

Primary hyperparathyroidism: new concepts in clinical, densitometric and biochemical features

Primary hyperparathyroidism (PHPT) is characterized most commonly now as an asymptomatic disorder with hypercalcaemia and elevated levels of parathyroid hormone (PTH). The elevation in PTH is detected by both the standard immunoradiometric assays (IRMA) and a more recent IRMA that detects only the 1-84 full-length PTH molecule. The serum calcium concentration is usually <1 mg dL(-1) above normal. Recently, another variant of PHPT (normocalcaemic PHPT) has been described in which the serum calcium is normal but the serum PTH is elevated, in the absence of any secondary cause for PTH elevation. Although usually sporadic, PHPT also occurs in inherited syndromes. Skeletal manifestations are appreciated by densitometry showing a typical pattern in which cancellous bone of the lumbar spine is reasonably well preserved whilst the cortical bone of the distal third of the radius is preferentially reduced. Although reduced in incidence, renal stones remain the most common overt complication of PHPT. Other organs are theoretical targets of PHPT such as the neurobehavioural axis and the cardiovascular system. Vitamin D looms as an important determinant of the activity of the PHPT state. The 2002 NIH Workshop on asymptomatic PHPT has led to revised guidelines to help doctors determine who is best advised to have parathyroid surgery and who can be safely followed without surgery. New information about the natural history of PHPT in those who did not undergo surgery has helped to define more precisely who is at-risk for complications. At the NIH workshop, a number of items were highlighted for further investigation such as pharmacological approaches to controlling hypercalcaemia, elevated PTH levels and maintaining bone density.