Plasma calcitonin in normal man. Differences between men and women.

We measured plasma calcitonin concentrations in healthy volunteers (20 men, ages 23-45 yr, mean, 30 yr; 25 women, ages 21-46 yr, mean, 30 yr) with a radioimmunoassay capable of detecting 5 pg of calcitonin/500 mul incubation volume, or 25 pg/ml of unextracted plasma. All subjects had 4-h calcium infusion (15 mg Ca/kg), and 24 subjects had intravenous pentagastrin injection (0.5 mug/kg) on separate days. Men had higher basal plasma immunoreactive calcitonin concentrations than women (P < 0.001): mean, 49 pg/ml (range, <25-73) and 31 pg/ml (range, <25-51), respectively. 18 of the 20 men (90%) responded to induced hypercalcemia with increases in plasma immunoreactive calcitonin; only 14 of the 25 women (56%) responded. In men, the mean increase of plasma immunoreactive calcitonin+/-SE was 58+/-9 pg/ml, but for women was only 25+/-6 pg/ml. 8 of 10 men (80%) responded to pentagastrin with an increase of plasma immunoreactive calcitonin >30 pg/ml, compared with such a response in only 1 of 14 women (7%). These differences of plasma immunoreactive calcitonin responses between the sexes were statistically significant (calcium infusion, P < 0.02; pentagastrin, P < 0.001). The physiologic importance of these observations is unknown, but we speculate that a lifelong, relative deficiency of calcitonin in some women could play a role in age- and sex-related bone loss, particularly during the estrogen-deficient postmenopausal years.

Pre- and postoperative studies of plasma calcitonin in primary hyperparathyroidism.

The importance of calcitonin in the homeostatic response to the chronic hypercalcemia of primary hyperparathyroidism is uncertain. To clarify this issue, we have used a new, sensitive radioimmunoassay for human calcitonin to measure basal plasma calcitonin concentrations in 50 patients with primary hyperparathyroidism (32 female, 18 male). We assayed calcium-stimulated calcitonin concentrations preoperatively in 22 of the patients (16 female, 6 male) and postoperatively in 6. Finally, we assayed pentagastrin-stimulated calcitonin concentrations preoperatively in eight of the patients (three female, five male). Plasma calcitonin values after an overnight fast were indistinguishable from those in normal subjects (mean+/-SE, males, 48+/-3 normal and 46+/-5 pg/ml hyperparathyroid, females, 31+/-2 normal and 37+/-3 pg/ml hyperparathyroid.) Among hyperparathyroid patients of both sexes, increases of calcitonin during Ca infusion (15 mg Ca/kg in 4 h) were within normal limits. However, the mean maximal increase of calcitonin was significantly lower in hyperparathyroid than in normal subjects (P < 0.05). In six patients normocalcemic 5-15 mo after parathyroid surgery, fasting plasma calcitonin values were not significantly different, but responses to Ca infusion were greater than preoperatively (Delta calcitonin +/-SE: 13+/-4 preoperatively and 53+/-35 pg/ml postoperatively). The mean maximal increase of calcitonin after pentagastrin (0.5 mug/kg i.v.) was slightly lower than normal in the patients (mean+/-SE, males, 45+/-8 normal and 38+/-10 pg/ml hyperparathyroid, females, 6+/-2 normal and 0 pg/ml hyperparathyroid). Thus, primary hyperparathyroidism is accompanied by normal steady-state concentrations of circulating calcitonin, and normal-to-blunted C-cell responses to pentagastrin or induced hypercalcemia, the response to calcium generally increasing after successful parathyroid surgery. These results clearly show that primary hyperparathyroidism is not characterized by hypercalcitoninemia. The seemingly paradoxical absence of elevated steady-state calcitonin concentrations may be accounted for partly by decreased secretory reserve. However, primary hyperparathyroidism may also be accompanied by an increase in the threshold of sensitivity for calcium stimulation of calcitonin secretion.

Immunochemical heterogeneity of calcitonin in plasma of patients with medullary thryoid carcinoma.

Marked discrepancies (values up to four times higher in on assay than in the other) were observed when the plasma concentration of immunoreactive human calcitonin (iCT) was measured by two radioimm8noassays in 18 patients with medullary thyroid carcinoma. The two antisera used had different binding affinities for the NH2- and COOH-terminal regions of synthetic calcitonin monomer (CT-1-32). Except for this difference, the assays were identical and reacted equally with CT 1-32. Plasma samples from patients with medullary thyroid carcinoma were gel filtered on columns of Bio-Gel P-150, and the immunoreactivity in column effuent fractions was measured with both assays. The one utilizing the antiserum with prominent NH2-terminal binding affinity (and giving higher iCT values) recognized at least five molecular species that eluted with or before CT 1-32. The other assay, utilizing the antiserum with a COOH-terminal binding affinity, recognized two fo these molecular species-one eluting with CT 1-32 and the other in a position consistent with a dimer. A mixture of athreotic asthma and added CT 1-32 contained a single immunologic species that was recoqnized equally by both antisera. No forms smaller than CT 1-32 were detected in any study. The results suggest that iCT circulating in the plasma of patients with medullary thryoid carcinoma is hetergeneous. The absolute iCT concentration measured by radioimmunoassays depends on recognition of these distinct molecular species as well as on the specific binding affinities of the antiserum used to detect them. These observations may partially explain the variations among iCT values reported by different laboratories.

Etiology of hyperparathyroidism and bone disease during chronic hemodialysis. 3. Evaluation of parathyroid suppressibility.

Parathyroid function was assessed by calcium infusions (4-8 h) in 16 patients with chronic renal insufficiency being treated by long-term hemodialysis. The concentrations of two immunoreactive species of parathyroid hormone in plasma (iPTH-9, mol wt 9500; iPTH-7, mol wt 7000) were estimated by radioimmunoassays utilizing two relatively specific antisera. Control values of the smaller species, iPTH-7, were uniformly high, whereas values of iPTH-9 were normal in 12 of 19 studies. Response of iPTH-7 to calcium infusions was variable, with significant decreases occurring only five times in 27 infusions. Concentrations of iPTH-9, however, decreased during every calcium infusion. In contrast to these acute responses, five of six patients studied during periods of dialysis against both low (< 6 mg/100 ml) and high (7-8 mg/100 ml) calcium concentrations in the dialyzate showed a decrease in values of iPTH-7 during the period of dialysis against the higher calcium concentration. It is concluded that plasma concentrations of iPTH-9 reflect primarily the moment-to-moment secretory status of the parathyroid glands, while concentrations of iPTH-7 reflect more closely chronic parathyroid functional status. It is further concluded that the failure of iPTH-7 to decrease during induced hypercalcemia should not be equated with autonomy of parathyroid gland function.

Preoperative diagnosis of occult parathyroid hyperplasia by calcium infusion in patients with multiple endocrine neoplasia, type 2a.

Hereditary multiple endocrine neoplasia, type 2 (MEN 2) comprises medullary thyroid carcinoma (MTC) and bilateral pheochromocytoma; the syndrome includes two major variants, MEN 2a (normal appearance, parathyroid disease common) and MEN 2b (mucosal neuromas, Marfanoid habitus, parathyroid disease rate). Patients with MEN 2a may be normocalcemic, with normal basal serum immunoreactive parathyroid hormone (iPTH) levels, yet have parathyroid hyperplasia discovered during thyroid surgery. In an attempt to predict the presence of this occult parathyroid hyperplasia, we performed calcium infusion (15 mg Ca++/kg/4 hours) in six patients with MEN 2a, seven patients with MEN 2b, and eight normal subjects. iPTH was measured in samples taken at one hour intervals during the infusion with a sensitive radioimmunoassay (antiserum GP 1M [Arnaud]). The iPTH values (expressed as per cent of the basal value) in the normal, MEN 2a, and MEN 2b groups at the fourth hour were 38.0 +/- 3.8% (mean +/- SE), 79.2 +/- 7.2%, and 47.8 +/- 5.2%. These iPTH values for patients with MEN 2a were significantly different from normal (P less than 0.001) and from those of the patients with MEN 2b (P less than 0.001). All MEN 2a patients had parathyroid hyperplasia at cervical exploration; parathyroid histology in the MEN 2b patients was normal. Failure of iPTH suppressibility in the MEN 2a patients was not due either to the plasma calcitonin or to achieved serum calcium concentrations. The normal iPTH suppressibility in MEN 2b is consistent with the concept that the parathyroid disease in MEN 2a is genetically determined, and not secondary to MTC and high plasma calcitonin concentration. Calcium infusion combined with the measurement of serum iPTH levels may detect occult parathyroid hyperplasia in patients with MEN 2a, normocalcemia, and normal basal iPTH values. The identification and follow-up of similar patients should establish the natural history of this unusual parathyroid disease.

Advances and controversies in the diagnosis and management of medullary thyroid carcinoma.

Recent advances in the diagnosis and treatment of medullary thyroid carcinoma (MTC) have been significant, but some issues remain controversial. MTC may occur either as a hereditary or a nonhereditary entity. Hereditary MTC can occur either alone--familial MTC (FMTC)--or as the thyroid manifestation of multiple endocrine neoplasia type 2 (MEN 2) syndromes (MEN 2A and MEN 2B). These hereditary disorders are due to germline mutations in the RET proto-oncogene. Early diagnosis and treatment considerably improve the prognosis in patients with MTC. Genetic testing can identify almost all affected individuals with hereditary disease and permits early thyroidectomy in gene carriers. Plasma CT is an excellent marker for postoperative follow-up. Imaging studies help delineate recurrent or metastatic lesions. Treatment of recurrent or metastatic disease is primarily surgical, including either palliative or microdissective surgery. Radiation therapy is reserved for skeletal metastasis or nonresectable metastatic MTC. Efficacy of current chemotherapy programs is not well established. Overall, the 10-year survival rates are approximately 65%.

Stimulation tests for diagnosis of medullary thyroid carcinoma.

We compared the maximal calcitonin secretion produced by pentagastrin, calcium, and glucagon for preoperative detection of medullary thyroid carcinoma in four subjects with normal or slightly increased plasma immunoreactive calcitonin (iCT) levels. In each case, pentagastrin administration produced higher peak iCT levels (5- to 36-fold increases over basal) than did calcium infusion (by 1.9- to 10.3-fold) and glucagon administration (by 3.6- to 27.4-fold). These preliminary studies suggest that pentagastrin is an effective agent for use in rapid stimulation tests designed to detectmedullary thyroid carcinoma in asymptomatic patients who have normal basal iCT concentrations.

Prolonged remission of metastatic follicular thyroid carcinoma.

Follicular thyroid carcinoma is associated with an extremely poor prognosis when metastatic lesions occur. Although radioiodine therapy for metastatic disease can extend patient survival for several years, its effect is usually only palliative. Herein we describe a 47-year-old man with metastatic follicular thyroid carcinoma who was in clinical remission for 30 years after surgical and radioiodine treatment of the original disease. To our knowledge, this is the longest reported remission of this disease. Possible reasons for the prolonged survival were "young" age at diagnosis, diploid DNA content of the tumor, skeletal lesions responsive to 131I therapy, and limited pulmonary disease.

Bilateral adrenal medullary hyperplasia in multiple endocrine neoplasia, type 2: the precursor of bilateral pheochromocytoma.

An asymptomatic 12-year-old girl with multiple endocrine neoplasia, type 2, had high urinary levels of vanillylmandelic acid that suggested pheochromocytoma; she also had bilateral medullary thyroid carcinoma and hyperparathyroidism. Her mother and maternal aunt and uncle had bilateral pheochromocytoma (metastatic in the former two). Bilateral adrenalectomy was performed. Diffuse, non-nodular adrenal medullary hyperplasia was present. This hyperplasia was characterized by increased medullary mitotic activity, decreased corticomedullary ratio, increased total adrenal weight, and increased total catecholamine content (left adrenal). The results in this case suggest that diffuse hyperplasia of the adrenal medulla may be the precursor of pheochromocytoma in patients with this syndrome.

Use of 131I-MIBG scintigraphy in the evaluation of suspected pheochromocytoma.

Studies at the University of Michigan have shown that 131I-metaiodobenzylguanidine (131I-MIBG) is an effective agent for the diagnosis and localization of pheochromocytomas and paragangliomas. We conducted a study that confirmed and expanded that finding. From January 1983 to March 1984, 48 patients at our institution had 51 131I-MIBG scans during the workup of suspected sporadic or metastatic pheochromocytoma. Scintigrams were obtained after 500 microCI of 131I-MIBG had been administered intravenously. The final diagnosis (true-positive, false-negative, or false-positive result) was made at operation and pathologic examination. A true-negative diagnosis was confirmed by normal plasma and fractionated urinary levels of catecholamines and metabolites and, in most patients, computed tomography (CT). There were 20 true-positive studies (6 pheochromocytomas, 4 paragangliomas, and 10 metastatic or recurrent pheochromocytomas) and 24 true-negative studies. One patient with a suspected recurrent paraganglioma near the bladder had a false-positive 131I-MIBG scan (and also a false-positive (CT). Among six patients with false-negative scintigrams (three pheochromocytomas, one paraganglioma, and two metastatic lesions), one also had a false-negative CT. The overall sensitivity of 131I-MIBG scanning was 77%, specificity was 96%, and accuracy was 86%. This test is fairly sensitive in the workup of patients with known or suspected recurrent or metastatic pheochromocytoma. It may also be helpful in the evaluation of suspected sporadic pheochromocytoma when CT findings are normal.

Medullary thyroid carcinoma: clinicopathologic features and long-term follow-up of 65 patients treated during 1946 through 1970.

We retrospectively reviewed the medical records of 65 consecutive patients with medullary thyroid carcinoma, who had had their primary surgical treatment at the Mayo Clinic during the years 1946 through 1970. Of these patients, 58 had sporadic and 7 had familial medullary thyroid carcinoma. Thyroid nodules were the most common initial manifestation. Near-total thyroidectomy was the most frequent initial operation. Survival was affected by the following factors: male sex, familial inheritance, size of the tumor, stage of the tumor (American Joint Committee on Cancer), and completeness of initial resection of the tumor. The mean duration of follow-up was 23.5 years, and the maximal follow-up was 36 years. Among 52 patients without initial distant metastatic involvement and with complete resection of the tumor, 20-year survival free of distant metastatic lesions was 81%. Overall 10- and 20-year survival rates were 63% and 44%, respectively. Because of the substantial morbidity and mortality associated with medullary thyroid carcinoma, early diagnosis and thorough initial resection of the tumor are important.

Adrenal medullary disease in multiple endocrine neoplasia, type 2: pheochromocytoma and its precursors.

Multiple endocrine neoplasia, type 2 (MEN-type 2), designates the syndrome of medullary thyroid carcinoma, pheochromocytoma, and occasional parathyroid hyperplasia. The thyroid carcinoma, which is usually bilateral and multicentric, is preceded by multifocal C-cell hyperplasia. The adrenal gland manifests pheochromocytoma, which is frequently bilateral and multicentric, and may be malignant. To test the hypothesis that diffuse adrenal medullary hyperplasia is a precursor of pheochromocytoma in this syndrome, we studied the adrenal glands of 19 patients who had MEN-type 2. The findings in the adrenal medulla in these 19 patients were: synchronous bilateral pheochromocytoma in 9 (metastatic in 3); asynchronous bilateral pheochromocytoma in 1 (metastatic); unilateral pheochromocytoma with contralateral diffuse and nodular hyperplasia in 2; unilateral pheochromocytoma with contralateral diffuse hyperplasia in 2; unilateral pheochromocytoma in 1; bilateral nodular hyperplasia in 1; bilateral diffuse hyperplasia in 1; and no abnormality in 2. This spectrum of adrenal medullary pathology suggests that diffuse and nodular medullary hyperplasia are precursors of pheochromocytoma in MEN-type 2.

Bilateral subtotal adrenal resection for bilateral pheochromocytomas in multiple endocrine neoplasia, type IIa: a case report.

Our treatment philosophy for the management of the adrenal glands in patients with multiple endocrine neoplasia, type IIa has been bilateral total adrenalectomy. In the patient described, exceptional and pressing reasons necessitated preservation of adrenocortical function. Bilateral pheochromocytomas were resected with preservation of the adrenal cortices. Adrenocortical function was normal 36 months after resection. Although the patient remained symptom free, elevated basal immunoreactive plasma calcitonin levels suggested the presence of residual or metastatic medullary thyroid carcinoma. There was no evidence of recurrent pheochromocytoma.

Pentagastrin promotes prolactin release in patients with medullary carcinoma of the thyroid.

Both calcitonin and gastrin have been found in the mammalian central nervous system, including the pituitary. Following a pentagastrin infusion in several patients with medullary carcinoma of the thyroid, we noted a coincident increase in plasma calcitonin and prolactin (PRL) levels. In order to evaluate further the influence of pentagastrin on human PRL release, a pentagastrin infusion was administered to 13 patients with active medullary carcinoma of the thyroid (MTC), eight subjects with inactive MTC, eight family members without MTC, and ten normal subjects. Plasma mean +/- SE PRL levels were significantly (P less than 0.01) increased in the active MTC patients from 7.6 +/- 0.5 to 12 +/- 1.4 ng/mL by 15 minutes post pentagastrin. Plasma mean +/- SE calcitonin levels increased in parallel with the plasma PRL levels from 0.28 +/- 0.1 to a peak of 1.9 +/- 0.9 ng/mL at 5 minutes post pentagastrin. A significant (P less than 0.05) correlation was found between the percentage increase in plasma calcitonin concentrations and plasma PRL levels at five and ten minutes post pentagastrin stimulation in this group of active MTC patients. Significant increases in serum calcitonin levels in the other groups post pentagastrin were of lesser magnitude and were not associated with a significant increase in PRL release. This latter observation suggested that neither the stress of the infusion nor the multiple endocrine neoplasia type 2 nor the pentagastrin was responsible for the observed increase in plasma PRL levels in the active MTC patients. These findings suggest, but do not prove, that calcitonin is a PRL-releasing factor in humans.

Medullary carcinoma in children. Results of early detection and surgery.

Early diagnosis and surgical treatment of medullary carcinoma of the thyroid (MCT) in children is essential to decrease the likelihood of metastatic spread. To determine the optimal timing of screening and surgery, we reviewed all children younger than 16 years old who were undergoing surgical treatment. From 1970 to 1988, 33 children 6 months old to 15.9 years old (mean, 9 years old) with MCT or C-cell hyperplasia or both underwent total thyroidectomy. Follow-up was 4 months to 15 years after surgery (mean, 9 years). Six of 31 patients presented with a neck mass. Basal immunoreactive calcitonin level was increased in 3 of 7 patients with C-cell hyperplasia alone, in 10 of 18 patients with nonmetastatic MCT, and in all 5 patients with metastatic MCT. At the time of surgery, 7 patients had C-cell hyperplasia, 19 patients had MCT without metastasis, and 7 patients had MCT with metastases. All children with metastasis were more than 12 years old. Medullary carcinoma of the thyroid was seen as early as age 6 months in a child with multiple endocrine neoplasia type IIb (MEN-IIb) and age 3 years in a child with MEN-IIa. At follow-up, 25 patients were free of disease and 8 had had recurrent disease. Two of the 8 patients with MEN-IIb had died. All 6 children with a neck mass at presentation had recurrent disease. Of 27 patients diagnosed by screening, 25 had no evident disease and 2 had persistent disease. Thus, in children with MEN-II syndromes, screening studies are highly effective in detecting MCT. All children with MEN-IIb should be studied shortly after birth, and those with MEN-IIa should be studied by 1 year old.

Primary hyperparathyroidism in patients with multiple endocrine neoplasia syndromes. Surgical experience.

Forty-five patients with biochemically documented primary hyperparathyroidism as part of multiple endocrine neoplasia syndrome types 1 or 2 were surgically treated from 1960 through 1980. Hyperplasia occurred in 69% of the patients, single adenoma in 27%, and double adenomas in 4%. All but two patients with hyperplasia underwent subtotal parathyroidectomy. In this group, the cure rate was 93% and the incidence of permanent postoperative hypoparathyroidism 23%. In the adenoma group, treatment included excision of the adenoma and biopsy of at least one other gland. The cure rate was 76%, with no postoperative hypoparathyroidism. Analysis of patients with persistent hyperparathyroidism suggested that failure to recognize multiple gland disease was the principal cause of postoperative hypercalcemia. In view of the high incidence of hypocalcemia after subtotal parathyroidectomy, approximately 500 mg of tissue should be cryopreserved to allow transplantation should hypocalcemia ensue postoperatively.

Hypercalcemia and primary hepatic tumors.

We treated a case of hypercalcemia and primary liver tumor and reviewed a series of such cases treated at the Mayo Clinic (Rochester, Minn). Primary tumor of the liver was diagnosed in 192 patients (152 had hepatocellular carcinomas; 40, cholangiocarcinomas) between 1969 and 1980. Hypercalcemia of unknown cause was found in eight patients with hepatocellular carcinoma (5.3%) and seven with cholangiocarcinoma (17.5%). Five hypercalcemic patients had serum immunoreactive parathyroid hormone values consistent with ectopic hyperparathyroidism. An additional five patients had high serum calcium, low phosphate, and low chloride concentrations that met Lafferty's criteria for pseudohyperparathyroidism. Our results suggest that hypercalcemia associated with primary hepatic tumors is relatively common, and incidences vary according to the type of primary tumor. Hypercalcemia may be controlled when surgical excision of the primary tumor is possible.

Brain metastases from medullary thyroid carcinoma in a patient with multiple endocrine neoplasia type 2A.

Medullary thyroid carcinoma (MTC) is an uncommon thyroid cancer occurring in less than 10% of patients with thyroid cancer. Brain metastasis from MTC is exceedingly rare. Only six cases of brain metastasis from MTC have been reported in the literature and none had MTC as a part of multiple endocrine neoplasia (MEN) syndrome. We report a 42-year-old Caucasian male with MEN 2A who presented with neurological symptoms 25 years after total thyroidectomy with lymphadenectomy for MTC metastatic to local lymph nodes. A brain magnetic resonance imaging (MRI) showed a 4-cm cystic mass and a 1-cm nodule in the left frontal-parietal lobe in addition to a 0.8-cm cystic mass in the left frontal lobe and multiple tiny cerebellar metastatic lesions. Partial resection of the cerebral metastasis followed by whole brain radiotherapy resulted in resolution of the neurological symptoms. However, the patient had multiple systemic metastasis from the MTC and he died of systemic complications due to metastatic MTC. To our knowledge this is the first report of brain metastases from MTC in a patient with MEN 2A.

Multiple endocrine neoplasia with skeletal manifestations.

There are three types of familial multiple endocrine neoplasia, but type 2b, which is characterized by medullary thyroid carcinoma, pheochromocytoma, and ganglioneuromatosis, is the only one in which patients also have skeletal anomalies. These musculoskeletal abnormalities include marfanoid habitus, pes cavus, talipes equinovarus, slipped capital femoral epiphysis, kyphosis, scoliosis, lordosis, increased joint laxity, and weakness of the proximal muscles of the extremities. Affected patients have several facial abnormalities as well, the most striking being enlargement of the lips. Therefore, when a patient is seen with one or more of these musculoskeletal defects, the diagnosis of type-2b multiple endocrine neoplasia should be considered. If the characteristic facial features of the disorder are present, the patient should have a prompt examination for medullary thyroid carcinoma and pheochromocytoma.

Biologic markers in cancer diagnosis and treatment.

We have reviewed several tumor markers that our advocates feel are now clinically useful, involve current assay technology, and are based on already available information. These include, in selected instances, estrogen receptors for breast cancer, thyrocalcitonin for medullary cancer of the thyroid, prostatic acid phosphatase for cancer of the prostate, alpha-fetoprotein for hepatocellular cancer, and carcinoembryonic antigen for monitoring colon cancer. We have considered the potential use of measurement of serum proteases and protein degradation products due to their activity as possible future areas of development, and we have explored measurement of tissue aryl hydrocarbon hydroxylase to identify populations at risk of cancer resulting from chemical carcinogenesis. It is clear that the study of tumor markers is already improving patient care in some specific areas and offers exciting potential for the future.