Occurrence of other endocrine tumours in primary hyperparathyroidism

Molecular and Clinical Spectrum of Primary Hyperparathyroidism

Recent data suggest an increase in the overall incidence of parathyroid disorders, with primary hyperparathyroidism (PHPT) being the most prevalent parathyroid disorder. PHPT is associated with morbidities (fractures, kidney stones, chronic kidney disease) and increased risk of death. The symptoms of PHPT can be nonspecific, potentially delaying the diagnosis. Approximately 15% of patients with PHPT have an underlying heritable form of PHPT that may be associated with extraparathyroidal manifestations, requiring active surveillance for these manifestations as seen in multiple endocrine neoplasia type 1 and 2A. Genetic testing for heritable forms should be offered to patients with multiglandular disease, recurrent PHPT, young onset PHPT (age ≤40 years), and those with a family history of parathyroid tumors. However, the underlying genetic cause for the majority of patients with heritable forms of PHPT remains unknown. Distinction between sporadic and heritable forms of PHPT is useful in surgical planning for parathyroidectomy and has implications for the family. The genes currently known to be associated with heritable forms of PHPT account for approximately half of sporadic parathyroid tumors. But the genetic cause in approximately half of the sporadic parathyroid tumors remains unknown. Furthermore, there is no systemic therapy for parathyroid carcinoma, a rare but potentially fatal cause of PHPT. Improved understanding of the molecular characteristics of parathyroid tumors will allow us to identify biomarkers for diagnosis and novel targets for therapy.

Multiple endocrine neoplasia type 1 and Zollinger-Ellison syndrome: a prospective study of 107 cases and comparison with 1009 cases from the literature

In patients with multiple endocrine neoplasia type 1 (MEN1), the most common functional pancreatic endocrine tumor (PET) syndrome is Zollinger-Ellison syndrome (ZES). ZES has been well studied in its sporadic form (that is, without MEN1); however, there are limited data on patients with MEN1 and ZES (MEN1/ZES), and the long-term natural history is largely unknown. To address this issue we report the results of a prospective long-term National Institutes of Health (NIH) study of 107 MEN1/ZES patients and compare our results with those of 1009 MEN1/ZES patients in 278 case reports and small series in the literature. Patients were clinically, radiologically, and biochemically evaluated yearly for all MEN1 manifestations (mean follow-up, 10 yr; range, 0.1-31 yr). Compared with patients from the literature, the NIH MEN1/ZES patients more frequently had pituitary (60%) and adrenal (45%) disease and carcinoid tumors (30%), but had equal frequency of hyperparathyroidism (94%), thyroid disease (6%), or lipomas (5%). Twenty-five percent of both the NIH and the literature patients lacked a family history of MEN1; ZES was the initial clinical manifestation of MEN1 in 40%. ZES onset preceded the diagnosis of hyperparathyroidism in 45%. However, ZES was rarely (8%) the only initial manifestation of MEN1 if careful testing was done. ZES occurred before age 40 years in 50%-60% of the current patients, in contrast to older studies. The diagnosis of ZES is delayed 3-5 years from its onset and is delayed as long as in sporadic ZES cases. Pituitary disease and carcinoid tumors (gastric > bronchial, thymic) are more frequent than generally reported, whereas a second functional PET is uncommon. In patients with MEN1/ZES without a family history of MEN1, the MEN1 manifestations are not as severe. This study shows that MEN1/ZES patients differ in many aspects from those commonly reported in older studies involving few MEN1/ZES patients. In this study we have identified a number of important clinical and laboratory features of MEN1/ZES that were not previously appreciated, which should contribute to earlier diagnosis and improve both short- and long-term management.

Parathyroid glands and the multiple endocrine neoplasia syndromes and familial hypocalciuric hypercalcemia

Hypercalcemia is a variable feature of inherited endocrine disorders. In the multiple endocrine neoplasia (MEN) syndromes, generalized hyperparathyroidism is a common feature. It occurs much more frequently in patients with MEN type 1 as compared to patients with MEN type 2A. Unlike the MEN syndromes, patients with familial hypocalciuric hypercalcemia (FHH) have only hypercalcemia with no associated endocrinopathies. The hyperparathyroidism in patients with either of the MEN syndromes is managed by parathyroidectomy, whereas patients with FHH are managed nonoperatively. The specific genetic defects associated with MEN type 2 syndromes and FHH have been identified. They explain, in part, the clinical and pathophysiologic features of these diseases. The genetic defect causative of MEN type 1 will doubtless soon be found and thereby provide further insights into the molecular basis of calcium homeostasis. We will review the clinical presentation and the management of patients with these disorders. We will also review the recent molecular discoveries in MEN 2A, MEN 2B, and FHH, and define how they have altered the management of patients who have these syndromes.

Primary hyperparathyroidism in children

Primary hyperparathyroidism is an uncommon condition in childhood that is easily amenable to surgical treatment with excellent results. Pathologically, the parathyroid glands may show generalized hyperplasia or, more commonly, adenoma formation, the latter frequently being seen in adolescence. Two girls with solitary parathyroid adenomas and predominantly skeletal manifestations resembling rickets are reported, underlining the need to suspect and appropriately investigate these children. The literature on the subject is reviewed.

Screening for multiple endocrine neoplasia type 1 in patients with recognized pituitary adenoma

A total of 79 consecutive patients with pituitary tumours were screened for multiple endocrine neoplasia type 1 (MEN-1). The 79 patients included 21 patients with acromegaly, nine with Cushing's disease, 18 with prolactinomas, three with mixed pituitary adenomas (GH and PRL), and 28 patients with no detectable hypersecretion of hormones. The screening consisted of: (1) a family history, (2) a uniform medical history of the patient using a standard questionnaire, and (3) hormonal evaluation including measurements of the serum levels of insulin, gastrin, glucagon, somatostatin, vasoactive intestinal polypeptide and pancreatic polypeptide. Ionized calcium and glucose concentration in serum were also measured. We found no patients with the MEN-1 syndrome. In one patient, we found a transient elevation of serum concentrations of pancreatic polypeptide for which we have no explanation. In another patient, the serum gastrin concentration was elevated secondary to achlorhydria. No other endocrine disorders were found, and no patients had relatives with recognized endocrine pancreatic tumours, primary hyperparathyroidism (HPT), or pituitary adenomas.

Multiple endocrine syndrome type I. Clinical, laboratory findings, and management in five families

The clinical features of 20 patients from five families with multiple endocrine neoplasia syndrome type I (MEN-I) were studied. Nineteen patients (95%) had hyperparathyroidism. Five patients who had a diagnosis during surgery of adenoma and who had fewer than 3.5 glands removed had recurrence of hypercalcemia after surgery. Fourteen patients (70%) had pancreatic islet cell tumors. All had one or more elevated serum polypeptide hormones, and six had symptoms related to the hormones produced. Multiple pancreatic tumors were identified in the nine patients who underwent surgery. Three patients who died had a mean survival of 6.3 +/- 2.9 years. Eight patients had pituitary tumors; seven had macroadenomas. Of the eight patients with pituitary tumors, seven had high serum prolactin and responded to bromocriptine therapy, whereas the eighth patient had acromegaly treated with radiotherapy. It was concluded that hypercalcemia due to hyperparathyroidism in MEN-I syndrome patients should be managed by a resection of four glands and transplantation of one half gland into the forearm because none of the patients has shown evidence of a recurrence, and serum calcium levels have been normal. Pancreatic tumors, which are usually multiple, may be asymptomatic. Patients with these tumors usually have long survival rates, even with distant metastasis. Total pancreatectomy may be the method of choice, especially in patients with gastrinoma caused by the diffuse nature of the disease. Long-term follow-up is needed, however, with more patients. Pituitary tumors are primarily prolactin-producing tumors, and medical treatment is the method of choice.

Androgen producing adrenal adenoma. Report on a case associated with hyperparathyroidism

In a 41-year-old hirsute woman, severe hypercalcemia led to the discovery of hyperparathyroidism related to the involvement (hyperplasia/or adenoma) of the 4 parathyroid glands. Plasma and urinary DHA, plasma DHA-sulfate and delta 5 steroid precursors were elevated. Steroid hormone hypersecretion was stimulated by hCG and ACTH, and exhibited a paradoxical rise during dexamethasone administration. Computerized tomography scanning as well as arteriography disclosed bilateral adrenal hyperplasia and left adrenal adenoma. Bilateral adrenal vein catheterization indicated a left/right gradient for delta 5 steroids and delta 5 steroid sulfates. At surgery a left brown adrenal encapsulated adenoma was removed with a hyperplastic adrenal gland. Results of in vitro studies (adrenal steroid content and incubation) together with postadrenalectomy hormonal results suggest that the left brown adrenal adenoma was the main source of excessive androgen production. The infrequent association of an androgen-producing adrenal adenoma with hyperparathyroidism raises the hypothesis of multiple endocrine neoplasia syndrome. However, evidence for this diagnosis is lacking in the absence of other glandular involvement and of family history.

Parathyroid mitogenic activity in plasma from patients with familial multiple endocrine neoplasia type 1

Hyperplasia of the parathyroid glands is a central feature of familial multiple endocrine neoplasia type 1. We used cultured bovine parathyroid cells to test for mitogenic activity in plasma from patients with this disorder. Normal plasma stimulated [3H]thymidine incorporation, on the average, to the same extent as it was stimulated in a plasma-free control culture. This contrasted with the results of the tests with plasma from patients with familial multiple endocrine neoplasia type 1, in which parathyroid mitogenic activity increased 2400 percent over the control value (P less than 0.001). Plasma from these patients also stimulated the proliferation of bovine parathyroid cells in culture, whereas plasma from normal subjects inhibited it. Parathyroid mitogenic activity in plasma from the patients with familial multiple endocrine neoplasia type 1 was greater than that in plasma from patients with various other disorders, including sporadic primary hyperparathyroidism (with adenoma, hyperplasia, or cancer of the parathyroid), sporadic primary hypergastrinemia, sporadic pituitary tumor, familial hypocalciuric hypercalcemia, and multiple endocrine neoplasia type 2 (P less than 0.05). Parathyroid mitogenic activity in the plasma of patients with familial multiple endocrine neoplasia type 1 persisted for up to four years after total parathyroidectomy. The plasma also had far more mitogenic activity in cultures of parathyroid cells than did optimal concentrations of known growth factors or of any parathyroid secretagogue. This mitogenic activity had an apparent molecular weight of 50,000 to 55,000. We conclude that primary hyperparathyroidism in familial multiple endocrine neoplasia type 1 may have a humoral cause.

Multiple endocrine neoplasia syndromes

The multiple endocrine neoplasia (MEN) syndromes are characterized by autosomal dominant inheritance with a high degree of penetrance but varying expression. This review gives a classification of these syndromes and a short summary of the historical background. The pathogenesis of the disease and its possible origin in the APUD cell system are discussed together with the mechanisms underlying normal and ectopic hormone production by MEN tumors on the basis of recent findings in molecular endocrinology. The natural history and the clinical manifestations of the different syndromes are described. The sensitivity and discriminative capacity of the tests used to detect the syndromes in an early stage are compared. The choice of therapy and criteria for the timing and extensiveness of treatment are also considered. Lastly, problems associated with the ethical and legal aspects of screening, central registration, and monitoring of relatives at risk are described.

[Hypocalcemia in malignant diseases]

Hypercalcemia accompanies often malignant diseases. The majority of cases of malignancy complicated by hypercalcemia is induced by metastases involving bone, hypercalcemia may also accompany localised tumors. Various hormones have been implicated in the genesis of malignant hypercalcemia: ectopic secretion of parathyroid hormone by tumor or orthotopic secretion by concomitant primary hyperparathyroidism, prostaglandin activating osteoclasts, production of hypercalcemic factor other than these hormones. This review summarizes current knowledge about endocrine-mediated mechanisms which produce hypercalcemia and about its frequency and mechanism in different types of tumors.

Clinical significance of hyperparathyroidism in familial multiple endocrine adenomatosis type I (MEA I)

In order to investigate the suggestion that hyperparathyroidism in patients with familial MEA I has a mild and nonprogressive clinical course, we have compared clinical, biochemical, roentgenologic and histologic features of 29 patients with hyperparathyrodism originating from six families with the MEA I syndrome with those of 28 unselected patients with isolated nonfamilial hyperparathyroidism. The patients from the families with MEA I were significantly younger, had lower serum calcium and inorganic phosphate concentrations and a lower incidence of elevated alkaline phosphatase levels. Furthermore, they had multiple enlarged parathyroid glands and recurrence of the disease significantly more often. There was, however, no significant difference in the incidence of renal impairment, urolithiasis, subperiosteal resorption or large bone cysts on roentgenograms, histologic changes in bone biopsy specimens or mortality due to hyperparathyroidism. Therefore, the suggestion that this type of hyperparathyroidism has a milder clinical course is not confirmed in the present study.

Diagnostic and operative problems in multiple pheochromocytomas

Two children, aged 14 yr, with multiple pheochromocytomas are presented. Both patients had a positive family history. In the preoperative aortographies the intra-adrenal pheochromocytomas of both patients were well visualized, but not the extra-adrenal tumors of the first case. Chlorpromazine as an adrenergic blocking agent was successfully used in the preoperative treatment. Postoperative catecholamine excretion in the first case was repeatedly slightly increased indicating residual pheochromocytoma. In addition to the bilateral adrenal pheochromocytomas, multiple islet cell adrenomas and cholecystolithiasis were revealed at the operation of the second case. After bilateral adrenalectomy and total pancreaticoduodenectomy, regular follow-up examinations were carried out for 28 months. Hyperparathyroidism and signs of possible medullary thryoid carcinoma were discovered. Thus the patient had an unique pattern of MEA syndrome.

Parathyroidectomy: extent of resection and late results

Opinion is divided as to the necessary extent of parathyroid resection in primary hyperparathyroidism. Some surgeons urge that subtotal parathyroidectomy be performed routinely, while others reserve subtotal resections for patients with parathyroid hyperplasia. In a review of 102 patients treated by parathyroidectomy for primary hyperparathyroidism and subsequently followed up for an average of 6 years, there were 73 patients with parathyroid adenoma, 26 with hyperplasia and 3 with carcinoma. The adenoma was not found at the first operation in only 3 cases; in the other 70 after removal of the adenoma no further hypercalcaemia was observed during the follow-up period. Persistent or recurrent hypercalcaemia was a problem in 9 out of the 26 patients with primary hyperplasia who had inadequate resection at the first operation, and also in the 3 patients with carcinoma. Experience shows that peroperative biopsy with frozen section of all the parathyroids is useful in confirming their identity and can be a guide to the type of disease present and the appropriate extent of resection.