Edda Vignali

Minimally invasive, video-assisted parathyroid surgery for primary hyperparathyroidism

A new video-assisted surgical procedure for treatment of primary hyperparathyroidism combined with intraoperative quick PTH measurement was developed. This procedure was successfully used in 6 patients with a single parathyroid adenoma preoperatively localized by neck ultrasound examination.

Morphometric Vertebral Fractures in Postmenopausal Women with Primary Hyperparathyroidism

CONTEXT An increased risk of fracture in patients with primary hyperparathyroidism (PHPT) compared to the general population has been reported, but available data are controversial. OBJECTIVE The aim of the study was to evaluate the rate of vertebral fractures (VFs) by dual-energy x-ray absorptiometry in postmenopausal women with sporadic PHPT and compare the results with a control group. DESIGN AND SETTING A case-control study was performed at a referral center. PARTICIPANTS A total of 150 consecutive patients and 300 healthy women matched for age and menopausal age participated in the study. RESULTS VFs were detected in 37 of 150 (24.6%) patients and 12 of 300 (4.0%) controls (P < 0.0001). The majority of VFs were mild. Stepwise multiple logistic regression analysis showed that in PHPT patients lumbar spine bone mineral density was the only variable independently associated with the prevalence of VFs (P = 0.003). The rate of fracture was higher in symptomatic (34.1%) than asymptomatic (21.1%) patients, but this difference was not statistically significant (P = 0.15). Among asymptomatic patients, fracture rate was significantly higher in those who met the criteria for parathyroidectomy (28.1%) than in those who did not (11.1%) (P = 0.03). Compared to controls, the fracture rate was significantly higher in patients with symptomatic and asymptomatic PHPT who met the criteria for surgery (P < 0.0001), but not in those who did not meet the criteria (P = 0.06). CONCLUSIONS VF rate is increased in postmenopausal women with PHPT compared to controls, independently of whether they are classified as symptomatic or asymptomatic. The question of whether the finding of mild morphometric VFs in the latter represents an indication for parathyroid surgery remains to be established.

No Evidence for Mutations in the Calcium‐Sensing Receptor Gene in Sporadic Parathyroid Adenomas

Inactivating mutations of the calcium‐sensing receptor gene (CaR) might explain abnormalities in the regulation of both parathyroid cell proliferation and parathyroid hormone secretion. In a previous study, using RNAse A protection assay, no mutations were identified in a series of parathyroid specimens from patients with primary and secondary hyperparathyroidism, but the analysis was incomplete, since part of exon 6 could not be analyzed. In the present study, we examined the presence of mutations in the CaR gene in 20 parathyroid adenomas using direct sequencing. The entire coding region of the CaR gene was successfully amplified by polymerase chain reaction and directly sequenced. This analysis did not identify CaR gene mutations in any tumors studied. A polymorphism that encoded a single amino acid change (Ala826Thr) was identified in 4 parathyroid adenomas and in 8 of 50 normal unrelated subjects. Loss of heterozygosity studies were also performed on adenomas using markers for the locus of the CaR gene on chromosome 3q. No allelic loss was demonstrated. In conclusion, our results extend previous observation and suggest that clonal somatic mutations of the CaR gene and allelic loss at the CaR locus on chromosome 3q do not play a major role in the pathogenesis of sporadic parathyroid tumors.

Genetic analyses in familial isolated hyperparathyroidism: implication for clinical assessment and surgical management.

Objective  Familial isolated primary hyperparathyroidism (FIPH) can result from either incomplete expression of a syndromic form of familial primary hyperparathyroidism [multiple endocrine neoplasia type 1 (MEN 1), hyperparathyroidism–jaw tumour syndrome (HPT‐JT) or familial hypocalciuric hypercalcaemia (FHH)] or still unrecognized causes.

Skeletal Integrity in Men Chronically Treated with Suppressive Doses of L-Thyroxine†

We measured bone mineral density (BMD) (lumbar spine, femoral neck, Wards triangle, and trochanter) in 34 men given suppressive doses of levothyroxine (L‐T4) for a mean of 10.2 years. Indications for treatment were nontoxic goiter (n = 5) or thyroidectomy for differentiated thyroid cancer (n = 6) or nontoxic goiter (n = 3). Patients were followed at our institution and treated with the minimal amount of L‐T4 able to suppress thyroid‐stimulating hormone (TSH). At the time of evaluation, free T3 was normal in all cases, whereas free T4 was increased in 14 men (41.2%). The mean daily dose of L‐T4 was 172 ± 6 μg, and the cumulative dose of LT4 was 673 ± 71 mg. We found no significant difference between patients and age‐ and weight‐matched controls in BMD (g/cm2) at any site of measurement (lumbar spine 1.144 ± 0.12 vs. 1.168 ± 0.15; femoral neck 0.979 ± 0.13 vs. 1.001 ± 0.13; Wards triangle 0.854 ± 0.17 vs. 0.887 ± 0.15; and trocanther 0.852 ± 0.13 vs. 0.861 ± 0.13). BMD was not correlated with the duration of therapy, cumulative or mean daily dose of L‐T4, serum levels of free T4, free T3, osteocalcin, and bone alkaline phosphatase. Serum calcium and osteocalcin were slightly but significantly elevated in patients compared with controls, whereas there was no difference in intact parathyroid hormone, bone alkaline phosphatase, and sex hormone‐binding globulin (marker of thyroid hormone action). Our data suggest that L‐T4 suppressive therapy, if carefully carried out and monitored, using the smallest dose necessary to suppress TSH secretion, has no significant effects on bone metabolism and bone mass in men.

Increased prevalence of primary hyperparathyroidism in treated breast cancer.

Hypercalcemia occurring in patients with advanced breast cancer (BC) is generally due to osteolytic metastases or to the activity of circulating tumor-derived products. In these conditions, the production of endogenous PTH is reduced. The frequency of hypercalcemia due to primary hyperparathyroidism in breast cancer is unknown. We examined the occurrence of primary hyperparathyroidism in a large group of women with treated BC. A total of 100 consecutive women aged 28–80 years with treated breast cancer were enrolled. One hundred and two healthy age-matched women and 60 age-matched female patients with differentiated thyroid carcinoma examined before thyroidectomy were used as controls. Intact serum PTH and serum calcium were measured in all patients and controls. Hypercalcemia associated with elevated serum PTH concentration indicating primary hyperparathyroidism was found in 7 BC patients (7%) and in none of healthy women or patients with thyroid cancer. The pre-operative staging of BC patients with primary hyperparathyroidism was I in six and II in one of them, and no patient had evidence of distant metastases. A parathyroid adenoma was found in all 6 BC patients submitted to neck exploration, one patient refused surgery. Serum calcium and PTH concentrations returned to normal levels after surgery. Two BC patients had increased serum PTH and normal calcium concentrations. One of them had low serum 25-hydroxyvitamin D [25(OH)D]. One patient with spread bone metastases had neoplastic hypercalcemia with undetectable serum PTH concentration. All remaining 90 BC patients had serum calcium and PTH concentrations within normal limits, but their mean (±SD) values (9.6±0.5 mg/dl for serum calcium, 38.0±16.4 mg/dl for serum PTH ) were slightly but significantly greater than in normal controls (9.3±0.5 mg/dl, p=0.003 and 27.9±10.6 pg/ml, p=0.0001, respectively) and in patients with thyroid cancer (9.2±0.6 mg/dl, p=0.001 and 26.2±11.0 pg/ml, p=0.001), with no relationship with clinical staging or anti-tumor therapy. In conclusion: 1) an increased frequency of parathyroid adenoma was found in BC patients with mildly aggressive neoplastic disease; 2) in BC patients with no evidence of primary hyperparathyroidism mean serum PTH and calcium concentrations were significantly greater than in healthy controls and in patients with thyroid carcinoma; and 3) this finding was unrelated to clinical staging or anti-tumor therapy. Thus, primary hyperparathyroidism should be considered as a possible cause of hypercalcemia in patients with non-aggressive breast cancer. We suggest that serum PTH should be determined in all BC patients with increased serum calcium concentration, especially in those with no evidence of metastatic disease.

Calcium-sensing receptor gene polymorphisms in primary hyperparathyroidism

The calcium-sensing receptor (CaR) polymorphism A986S has been found to be associated with higher serum calcium levels in normal subjects, suggesting that this amino acid change might decrease the inhibitory activity of the mutated receptor, render the parathyroid cells more prone to proliferate, and eventually increase the risk of developing primary hyperparathyroidism (PHPT). The aim of the present study was to investigate the frequency of this and other 2 known CaR polymorphisms (R990G and Q1011E) in patients with PHPT and their effect on its phenotype. We studied 103 Italian patients with PHPT and 148 healthy Italian subjects and we compared the results in 50 pairs matched for sex, age and geographic provenience. A fragment of exon 7 of the CaR gene, containing the 3 polymorphic loci of interest (A986S, R990G, and Q1011E), was amplified by PCR and sequenced. Serum calcium and PTH levels, BMD and other biochemical and clinical parameters were evaluated. The frequency distribution of the A986S, R990G, and Q1011E polymorphisms in the 103 PHPT patients was 39.8%, 5.8%, and 2.0%, respectively. There was no difference in the frequency of the 3 CaR polymorphisms in the 50 matched pairs of patients and controls. We found no significant difference in several clinical and biochemical parameters between PHPT patients carrying or not the 986S allele. Finally, no relationship was observed between the 986S genotype and total and ionized serum calcium in control subjects. The A986S CaR polymorphism is the most common in Italian PHPT patients and the allotype AS does not appear to play a relevant role in the pathogenesis of PHPT and its severity. The A986S polymorphism does not correlate with serum calcium levels in normal Italian subjects.

Bcl-2, p53 and MIB-1 expression in normal and neoplastic parathyroid tissues

An altered control of the mechanisms involved in cell proliferation and programmed cell death (apoptosis) might play an important role in parathyroid tumorigenesis. We evaluated by immunohistochemistry the expression of bcl-2 and p53 proteins, as markers of apoptosis control, and MIB-1, as marker of cell proliferation, in a series of normal and neoplastic parathyroid tissues. The specimens were 33 normal parathyroids, 43 parathyroid adenomas and 3 parathyroid carcinomas. Results were scored as positive when more than 1% of cells were stained for MIB-1 and p53, and more than 10% for bcl-2. All normal parathyroids showed numerous bcl-2 positive cells (≥80%), low proliferation rate (MIB-1) and no p53 protein expression. Twenty-four (55%) adenomas were bcl-2 positive; in 16 of these the number of positive cells was high (>50%) and immunoreactivity was diffusely distributed within the adenoma; 8 cases showed a zonal staining pattern, in which groups of stained cells were surrounded by negative cells. Nineteen adenomas (45%) and all carcinomas were bcl-2 negative. A high proliferative rate (MIB-1) was found in all carcinomas and 4 adenomas (9%); all MIB-1 positive adenomas were bcl-2 negative. p53 was negative in all specimens. No significant differences in serum calcium and intact PTH levels nor in tumor size were found between bcl-2 negative and bcl-2-positive and MIB-1-positive and MIB-1-negative adenomas. An inverse, but not statistically significant (p=0.06) correlation was observed between the percentage of bcl-2 positive cells and serum calcium level in parathyroid adenomas. In conclusion, parathyroid adenomas are a heterogeneous group of lesions in which the pattern of bcl-2 and MIB-1 protein expression ranges between that of normal parathyroid (bcl-2 positivity and MIB-1 negativity) and that of parathyroid carcinoma (bcl-2 negativity and MIB-1 positivity). The question of whether the finding of the MIB-1 positive-bcl-2 negative phenotype identifies a subgroup of clinically more aggressive adenomas remains to be established.

CDC73 mutational status and loss of parafibromin in the outcome of parathyroid cancer

Inactivating mutations of the CDC73 tumor suppressor gene have been reported in parathyroid carcinomas (PC), in association with the loss of nuclear expression of the encoded protein, parafibromin. The aim of this study was to further investigate the role of the CDC73 gene in PC and evaluate whether gene carrier status and/or the loss of parafibromin staining might have an effect on the outcome of the disease. We performed genetic and immunohistochemical studies in parathyroid tumor samples from 35 patients with sporadic PC. Nonsense or frameshift CDC73 mutations were detected in 13 samples suitable for DNA sequencing. Six of these mutations were germline. Loss of parafibromin expression was found in 17 samples. The presence of the CDC73 mutation as well as the loss of parafibromin predicted a high likelihood of subsequent recurrence and/or metastasis (92.3%, P=0.049 and 94.1%, P=0.0017 respectively), but only the latter was associated with a decreased overall 5- and 10-year survival rates (59%, P=0.107, and 23%, P=0.0026 respectively). The presence of both the CDC73 mutation and loss of parafibromin staining compared with their absence predicted a lower overall survival at 10- (18 vs 84%, P=0.016) but not at 5-year follow-up. In conclusion, loss of parafibromin staining, better than CDC73 mutation, predicts the clinical outcome and mortality rate. The added value of CDC73 mutational analysis is the possibility of identifying germline mutations, which will prompt the screening of other family members.

Genetic analysis of the MEN1 gene and HPRT2 locus in two Italian kindreds with familial isolated hyperparathyroidism

OBJECTIVES Familial hyperparathyroidism may occur as part of hereditary syndromes, including multiple endocrine neoplasia types 1 and 2 (MEN1 and MEN2A), hyperparathyroidism‐jaw tumour (HPT‐JT) syndrome and familial isolated hyperparathyroidism (FIHP). It is unclear whether the latter is a distinct genetic entity or a variant of MEN1 or HPT‐JT, where, because of reduced penetrance, only primary hyperparathyroidism (PHPT) is present. In the present study, we describe two unrelated Italian kindreds with FIHP, in which the clinical, histopathological and genetic analyses of the MEN1 gene and HPRT2 locus at 1q21‐32 suggest that both might be a variant of MEN1 and HPT‐JT syndromes.