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- Ahrén, B, et al.
(author)
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Effects of minor increase in serum calcium on the immunoheterogeneity of parathyroid hormone in healthy subjects and in patients with primary hyperparathyroidism
- 1995
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In: Hormone Research. - 0301-0163. ; 43:6, s. 9-294
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Journal article (peer-reviewed)abstract
- To study possible influences of a mild increase in serum-ionized calcium concentration that is seen during daily life on circulating parathyroid hormone (PTH) immunoheterogeneity, we used sequence-specific PTH assays to determine serum intact PTH, C-terminal PTH and N-terminal PTH following oral calcium (1.5 g) in healthy subjects (n = 7). This was also performed in patients with primary hyperparathyroidism (pHPT; n = 10) to see if their regulation of circulating PTH molecular forms is normal. Compared to healthy subjects, the patients were hypercalcemic (p < 0.05) and had higher levels of PTH in all three assays (p < 0.001). Following the oral calcium load, serum-ionized calcium increased by 0.08 +/- 0.03 mmol/l in the patients and by 0.07 +/- 0.03 mmol/l in the healthy subjects after 90 min, whereas serum intact PTH, C-terminal PTH and N-terminal PTH were reduced, both in the healthy subjects and in the patients. Suppression by calcium of both intact PTH and C-terminal PTH were impaired in the patients (p < 0.05 and p < 0.001), whereas suppression of N-terminal PTH was normal. Furthermore, the C/i and N/i ratios were higher at the highest calcium concentration achieved after calcium intake in the healthy subjects than in the basal state in the patients (p < 0.05), in spite of the larger degree of hypercalcemia in the latter (1.40 +/- 0.06 vs. 1.31 +/- 0.02 mmol/l; p < 0.05). Thus, (1) a minor increase in serum-ionized calcium that is seen during daily life alters the relative circulating concentrations of PTH versus its fragments; (2) the impaired sensitivity to calcium in pHPT is not evident for the suppression of N-terminal PTH, and (3) pHPT is accompanied by altered immunoheterogeneity of circulating PTH.
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- Ahren, B, et al.
(author)
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No correlation between insulin and islet amyloid polypeptide after stimulation with glucagon-like peptide-1 in type 2 diabetes
- 1997
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In: European journal of endocrinology. - : Oxford University Press (OUP). - 0804-4643 .- 1479-683X. ; 137:6, s. 643-649
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Journal article (peer-reviewed)abstract
- OBJECTIVES: To examine whether glucagon-like peptide-1 (GLP-1), which has been suggested as a new therapeutic agent in type 2 diabetes, affects circulating islet amyloid polypeptide (IAPP), a B-cell peptide of potential importance for diabetes pathophysiology. DESIGN: GLP-1 was administered in a buccal tablet (400 micrograms) to seven healthy subjects and nine subjects with type 2 diabetes. Serum IAPP and insulin levels were measured before and after GLP-1 administration. RESULTS: In the fasting state, serum IAPP was 4.1 +/- 0.3 pmol/l in the controls vs 9.8 +/- 0.9 pmol/l in the subjects with type 2 diabetes (P < 0.001). IAPP correlated with insulin only in controls (r = 0.74, P = 0.002) but not in type 2 diabetes (r = 0.26, NS). At 15 min after GLP-1, circulating IAPP increased to (6.0 +/- 0.5 pmol/l in controls P = 0.009) and to 13.8 +/- 1.2 pmol/l in type 2 diabetes (P = 0.021). In both groups, serum insulin increased and blood glucose decreased compared with placebo. In controls serum IAPP increased in parallel with insulin (r = 0.79, P = 0.032), whereas in type 2 diabetes the increase in IAPP did not correlate with the increase in insulin. CONCLUSION: Type 2 diabetes is associated with elevated circulating IAPP; GLP-1stimulates IAPP secretion both in healthy human subjects and in type 2 diabetes; IAPP secretion correlates with insulin secretion only in healthy subjects and not in type 2 diabetes.
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- Bergenfelz, A, et al.
(author)
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Immunoheterogeneity of parathyroid hormone pre- and postoperatively in primary hyperparathyroidism
- 1995
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In: Langenbecks Archiv für Chirurgie. - 0023-8236. ; 380:2, s. 24-119
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Journal article (peer-reviewed)abstract
- In primary hyperparathyroidism (pHPT), a preferential release of intact PTH (i-PTH) versus carboxylterminal PTH fragments is known to occur. We studied whether the release of amino-terminal PTH fragments (N-PTH) is also changed. Serum levels of i-PTH and N-PTH were determined under basal conditions and following oral intake of calcium in six patients with pHPT before and immediately after surgery and in seven healthy subjects. In the patients, baseline levels of both i-PTH and N-PTH were increased preoperatively. The increase was larger in i-PTH compared to N-PTH. Therefore, the N/i ratio was reduced compared to healthy subjects (P < 0.05). On the first postoperative day, serum i-PTH decreased to a larger extent than N-PTH, which increased the N/i ratio above that in healthy subjects (P < 0.05). On the 5th postoperative day, the N/i ratio was normalized. Preoperatively, the suppressibility of i-PTH calcium was impaired in the patients (P < 0.05), whereas the suppressibility of N-PTH was normal, resulting in unchanged N/i ratio during the oral calcium load. In contrast, the N/i ratio increased normally during the calcium load at day 5 postoperatively (P < 0.05). We therefore conclude that: (1) in pHPT, circulating PTH immunoheterogeneity is altered with a preferential release of intact PTH compared to N-terminal PTH fragments and this alteration is normalized after surgery, (2) the secretion of intact PTH and N-terminal PTH shows different sensitivity to inhibition by calcium.
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- Bergenfelz, A, et al.
(author)
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Intraoperative secretion of intact parathyroid hormone and amino-terminal parathyroid hormone fragments from normal parathyroid glands associated with solitary parathyroid adenoma
- 1997
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In: World Journal of Surgery. - : Springer Science and Business Media LLC. - 0364-2313 .- 1432-2323. ; 21:1, s. 30-35
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Journal article (peer-reviewed)abstract
- The nonadenomatous parathyroid glands associated with parathyroid adenoma in patients with primary hyperparathyroidism (pHPT) are assumed to exhibit suppressed secretion of parathyroid hormone (PTH). Because the function of these glands is of clinical importance for calcium homeostasis after surgery for pHPT, we studied the decrease of serum levels associated with intact PTH (i-PTH) and amino-terminal PTH (N-PTH) after excision of a parathyroid adenoma. Blood samples were obtained from the cubital vein and the inferior thyroid vein in six patients with pHPT. The results show that the levels of both i-PTH and N-PTH decreased after removal of the parathyroid adenoma (p < 0.05 for both). Because the reduction was more pronounced for i-PTH than for N-PTH, the N/i ratio increased from 0.54 +/- 0.33 to 3.76 +/- 1.62 (p < 0.05). Furthermore, the levels of i-PTH and N-PTH were higher centrally than peripherally both before and after adenoma excision (p < 0.05). The results therefore suggest that the secretion of i-PTH and N-PTH in the remaining normal-size parathyroid glands is not completely suppressed. Furthermore, in these parathyroid glands the secretion of amino-terminal PTH fragments is relatively predominant when compared to the release of the intact PTH. The findings underscore the importance of the N-terminal PTH fragment for maintaining calcium homeostasis during the early postoperative period after surgery for pHPT and may explain the rarity of prolonged hypocalcemia after parathyroidectomy.
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