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Original Studies |
Departments of Medical Sciences (D.G., B.E., K.Ö., B.S.) and Clinical Chemistry (M.S., G.L.), University Hospital, S-751 85 Uppsala, Sweden; and the Departments of Medicine (R.S.), Huddinge University Hospital and St. Göran Hospital, S-11281 Stockholm, Sweden
Address all correspondence and requests for reprints to: Britt Skogseid, M.D., Department of Endocrine Oncology, Division of Internal Medicine, University Hospital, S-751 85 Uppsala, Sweden. E-mail: britt.skogseid{at}medicin.uu.se
| Abstract |
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| Introduction |
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This study was designed to 1) evaluate the usefulness of basal CgA as a marker for early diagnosis of pancreatic endocrine tumors in MEN 1 patients, 2) investigate the value of adding measurements of CgA to PP and gastrin during the meal test, 3) recognize the degree of spontaneous variation in neuroendocrine tumor patients, and 4) identify the frequency of elevations of CgA in some nonendocrine diseases of the gut and pancreas.
| Subjects and Methods |
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MEN 1 subjects (groups AC)
Group A consisted of nine patients, five men and four women, who
did not fulfill the biochemical criteria for pancreatic endocrine tumor
diagnosis mentioned above and had no radiologically visible tumor in
the pancreas (Table 1
). However, eight
patients in this group had intermittently abnormal meal stimulation
tests, two patients had elevated serum proinsulin levels, and one had
slightly elevated plasma glucagon levels. Five of the patients had
increased serum calcium; the other four had previously been subjected
to surgery for primary HPT. Three had been treated for pituitary tumors
with surgery or bromocriptine, and another two showed
elevated PRL or GH. Their mean age was 46 yr (range, 3276 yr).
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Seven patients (three men and four women; mean age, 59 yr; range,
3971 yr) fulfilled the criteria for belonging to group C,
i.e. they all had demonstrable pancreatic endocrine tumors
either by percutaneous ultrasonography or computed tomography scan
(Table 1
). All were normocalcemic, and all but one had previously been
operated on for primary HPT. Altogether three of the seven patients
harbored pituitary lesions at inclusion in this study.
Non-MEN 1 subjects
Twenty-five patients (12 men and 13 women) with sporadic pancreatic endocrine tumor constituted group D. Their mean age was 55 yr (range, 2074 yr). One patient had an insulinoma, 3 had glucagonoma, 6 suffered from gastrinoma, 1 had a vasoactive intestinal polypeptide-secreting tumor, another suffered from combined insulinoma and glucagonoma, and the remaining 13 patients harbored nonfunctioning tumors. Twenty-two of the patients had proven metastases.
Group E consisted of seven patients (five men and two women; mean age, 62 yr; range, 4875) with nonendocrine pancreatic disease. Five suffered from a pancreatic adenocarcinoma, one had a benign exocrine pancreatic tumor, and another had chronic pancreatitis.
The inflammatory bowel disease (IBD) group consisted of 39 patients (33 men and 6 women) diagnosed to have inflammatory bowel disease (ulcerative colitis, n = 23; Crohns disease, n = 16) with up to 20 diarrhea episodes daily (mean, 3.3). The mean age in this group was 40 yr (range, 1781 yr).
In the control group we included 19 healthy volunteers, 9 men and 10 women. Their mean age was 37 yr (range, 2167 yr).
To assess the degree of spontaneous variation, CgA was measured on 2 consecutive days in 7 healthy individuals and in 40 neuroendocrine tumor patients. The patients constituted 21 with midgut carcinoids, 12 with sporadic pancreatic endocrine tumors, and 7 with MEN 1 syndrome with pancreatic endocrine lesions. The tumor patients had CgA values between 2.11060 nmol/L (mean, 108.1; median, 14.9).
In some rare cases, we observed a possible influence of nonsteroid anti-inflammatory drugs medication on circulating CgA levels. To assess this idea, CgA was analyzed in seven healthy controls (four men and three women; mean age, 43 yr) before and after daily oral ingestion of 200 mg ketoprofen during 1 week.
Hormone assays
Serum insulin, proinsulin, C peptide, PP, and gastrin as well as plasma glucagon were measured after 12 h of fasting, together with serum PRL, GH, and PTH. These hormones were analyzed as described previously (2, 16, 17, 18, 19, 20, 21, 22, 23). Serum calcium, serum albumin, blood glucose, and other routine serum markers were analyzed at the routine clinical chemistry laboratory. A standardized meal stimulation test was performed in patients and the 19 healthy controls as follows. After an overnight fast a 563-Cal mixed meal composed of 66 g carbohydrate, 18 g protein, and 22 g fat was eaten during 20 min. Blood for analysis of gastrin, PP, and CgA was collected 5 min before starting, just before starting, and at 10, 20, 30, 45, and 60 min after starting the meal. An elevation of PP or gastrin of more than 2 SD above the mean in normal controls was considered an abnormal response to the meal according to earlier comprehensive evaluation of the meal test (2). The CgA response to the meal was assessed in 18 MEN 1 patients (6 in group A, 9 in group B, and 3 in group C) and compared to the response in the 19 control subjects of the present study.
Blood samples for basal plasma CgA measurements were collected while subjects were fasting in the morning. Before 1995, the analysis was accomplished by RIA, as previously described (4). From 1995, CgA was analyzed by a novel method with a detection limit of 10 pmol/L and an interassay variation of 6.4% (24). As there is a strong correlation between the two methods (r = 0.96; P < 0.001; n = 320), the older values could be transformed to the new ones by multiplication by a factor of 0.015. The upper reference limit in this study was defined as 2 SD above the mean level of our control subjects, i.e. 3.7 nmol/L.
Statistics
Results are reported as the mean ± SD unless otherwise stated. Intergroup comparison of mean values was performed according to the nonparametric test of Kruskal-Wallis and Mann-Whitney U tests, as well as parametric Students t test for unpaired samples. Correlation between CgA and other hormones was calculated by linear regression. P < 0.05 was considered significant. The spontaneous variation in CgA was expressed as a percentage and calculated according to the following formula: (CgA on day 1 - CgA on day 2)/CgA on day 1.
| Results |
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Eleven of the 39 patients with IBD (28%) had CgA above the upper reference limit. Mean CgA did not differ between control subjects and the IBD patients. Although patients with Crohns disease had a tendency toward higher CgA than those with ulcerative colitis, the difference did not reach significance (P = 0.07). There was no correlation between CgA levels and the number of daily diarrhea episodes.
Six of 10 MEN 1 patients with hypercalcemia due to HPT had elevated
CgA. All 3 group A patients with primary HPT and increased CgA had some
sign of a pancreatic endocrine tumor (abnormal meal test in 2 cases and
elevated proinsulin in 1). In group B there was no difference in CgA
between the hyper- and normocalcemic patients, but the hypercalcemic
group A patients had near-significantly higher CgA levels than those
who were normocalcemic (nonparametric, P = 0.05;
parametric, P = 0.02; Table 3
). The highest CgA value among the
hypercalcemic patients was recorded in the only patient with
concomitant hypergastrinemia. There was no correlation between log
plasma CgA and log serum calcium or PTH. The CgA levels were not
significantly altered after surgery for primary HPT (but only 3
patients were evaluable in this respect). CgA was elevated in 10 of the
11 (90%) group B and C patients displaying high serum gastrin levels.
The corresponding figure for patients with insulin/proinsulin-producing
tumors was 9 of 17 (53%; Table 1
).
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During the meal test, the mean CgA increased 16% (within the reference range) in control subjects. In group A patients, CgA increased 25%, whereas in groups B and C, the responses were 31% and 20%, respectively. The maximum CgA values occurred between 3060 min after the onset of the meal.
In the patients with neuroendocrine tumors, the mean day to day
variation in CgA was 29.3 ± 22.4% (range, 0.0113.5%). The
patients with normal CgA (n = 3) had a mean variation of 27.0%
compared to 29.5% among those with elevated CgA (n = 37;
P = NS). The variation did not differ significantly
between the tumor types. In healthy subjects, mean day to day variation
was 21.0 ± 16.6% (range, 0.047%). This was not different from
the variation in the neuroendocrine tumor patients, although all CgA
values were normal in all healthy individuals. The day to day variation
is shown in Fig. 2
. Plasma CgA before and
after 1 week of ketoprofen ingestion in healthy individuals was not
significantly changed (2.7 ± 1.9 and 1.9 ± 0.7 nmol/L,
respectively; P = NS).
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| Discussion |
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Of the MEN 1 patients without established pancreatic endocrine tumor diagnosis, 44% showed CgA elevations. This finding might constitute false positive elevations. On the other hand, it could be due to CgA secretion from an otherwise undetectable tumor in the pancreas or represent secretion of CgA from other MEN 1 lesions. The majority of these patients will most likely develop pancreatic endocrine tumors and only two patients, both with normal CgA, lacked all signs of pancreatic endocrine tumor at inclusion in the study, although they later developed an abnormal PP response to the meal test. A long term prospective study will be necessary to actually pinpoint the efficacy of CgA as a marker for the very early onset of the pancreatic lesion in MEN 1, but in the meantime we recommend annual follow-up of known MEN 1 carriers with elevated CgA.
It has previously been shown that CgA is elevated in hypercalcemic primary HPT patients only when they have a concomitant Zollinger-Ellison syndrome (15). In our study, 6 of 10 MEN 1 patients with hypercalcemia due to primary HPT had increased CgA. All 6 showed elevations of at least 1 marker for pancreatic involvement. Serum gastrin was increased in 1 of these MEN 1 patients. Thus, our results may support the suggestion that coexisting pancreatic endocrine tumors are responsible for perceivable elevations of CgA in MEN 1, but not necessarily in gastrinomas (15).
Earlier studies have found elevated CgA in up to one third of patients with pituitary tumors. Whether these patients represented MEN 1 gene carriers was not determined (25, 26). We found elevated CgA in three of five MEN 1 patients with pituitary tumors. Since two of these three also had pancreatic endocrine tumors, no conclusions can be drawn about the impact of a pituitary tumor on the plasma CgA level in MEN 1 patients.
Our results indicate that slightly increased CgA may also occur in ulcerative colitis and Crohns disease as well as in patients with a variety of nonendocrine pancreatic diseases. Previously, OConnor and Deftos claimed that normal CgA levels were found in various nonpeptide-producing tumors (3). However, in their study, the cut-off limit was 6.4 SD above the mean CgA level in healthy controls. In our laboratory, upper reference limits are most commonly defined as 2 SD above the mean level in control subjects. When reanalyzing the data from the report by OConnor and Deftos and applying our principles for reference intervals, as much as 40% of their patients with pancreatic adenocarcinoma would have been considered to have elevated CgA. Thus, in accordance with the results from our study, moderate elevation of CgA in a patient disclosing radiological findings of a pancreatic lesion does not exclude an adenocarcinoma, and histological diagnosis is mandatory.
Conflicting data have been presented on the day to day variation of CgA in healthy subjects, with values between 021% (3, 27). In this study we found a spontaneous variation of 21% in CgA in healthy individuals (range, 0.047%), although all measurements were within the reference range. The variation of CgA in patients with neuroendocrine tumors, never previously assessed, is pronounced, most likely due to tumoral instability and liability to release hormones. Repeated measurements and careful interpretation are thus warranted when using CgA for treatment monitoring.
A recent comprehensive study evaluated the efficacy of CgA,
neuron-specific enolase, and the
-subunit of glyco-protein
hormones as circulating tumor markers in patients with neuroendocrine
tumors (28). CgA was found to be the most sensitive and specific of
these three. It was, however, concluded that some patients with
neuroendocrine tumors had normal levels of CgA, and some patients with
nonneuroendocrine diseases displayed elevated levels of CgA.
We conclude that CgA is the single most sensitive marker of pancreatic involvement in MEN 1. On the other hand, CgA elevations are less prominent in cases of limited disease and often within the same range as in patients with nonendocrine gastrointestinal or pancreatic diseases. Thus, mere CgA analysis cannot be recommended as a single marker for pancreatic tumor involvement in young MEN 1 patients. However, middle-aged MEN 1 patients harboring a substantial tumor burden frequently display high CgA levels. Finally, as the spontaneous day to day variation is not negligible, we emphasize that slight elevations of CgA should be interpreted with caution, and repeated measurements should be considered.
Received August 27, 1998.
Revised April 6, 1999.
Accepted May 14, 1999.
| References |
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-subunit, and chromogranin-A and their response to
thyrotropin-releasing hormone in clinically nonfunctioning,
-subunit-secreting, and gonadotroph pituitary adenomas. J Clin
Endocrinol Metab. 77:784789.[Abstract]
subunit
of glycoprotein hormones. J Clin Endocrinol Metab. 82:26222628.This article has been cited by other articles:
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L. Taupenot, K. L. Harper, and D. T. O'Connor The Chromogranin-Secretogranin Family N. Engl. J. Med., March 20, 2003; 348(12): 1134 - 1149. [Full Text] [PDF] |
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M. L. Brandi, R. F. Gagel, A. Angeli, J. P. Bilezikian, P. Beck-Peccoz, C. Bordi, B. Conte-Devolx, A. Falchetti, R. G. Gheri, A. Libroia, et al. CONSENSUS: Guidelines for Diagnosis and Therapy of MEN Type 1 and Type 2 J. Clin. Endocrinol. Metab., December 1, 2001; 86(12): 5658 - 5671. [Abstract] [Full Text] [PDF] |
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M. d'Herbomez, V. Gouze, D. Huglo, M. Nocaudie, F. Pattou, C. Proye, J.-L. Wemeau, and X. Marchandise Chromogranin A Assay and 131I-MIBG Scintigraphy for Diagnosis and Follow-Up of Pheochromocytoma J. Nucl. Med., July 1, 2001; 42(7): 993 - 997. [Abstract] [Full Text] [PDF] |
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