{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,4]],"date-time":"2026-05-04T12:40:47Z","timestamp":1777898447519,"version":"3.51.4"},"reference-count":0,"publisher":"S. Karger AG","license":[{"start":{"date-parts":[[2008,12,5]],"date-time":"2008-12-05T00:00:00Z","timestamp":1228435200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"},{"start":{"date-parts":[[2008,12,5]],"date-time":"2008-12-05T00:00:00Z","timestamp":1228435200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Horm Res"],"abstract":"<jats:p>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 &lt; 0.05) and had higher levels of PTH in all three assays (p &lt; 0.001). Following the oral calcium load, serum-ionized calcium increased by 0.08 \u00b1 0.03 mmol\/l in the patients and by 0.07 \u00b1 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 &lt; 0.05 and p &lt; 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 &lt; 0.05), in spite of the larger degree of hypercalcemia in the latter (1.40 \u00b1 0.06 vs. 1.31 \u00b1 0.02 mmol\/l; p &lt; 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.<\/jats:p>","DOI":"10.1159\/000184315","type":"journal-article","created":{"date-parts":[[2008,12,11]],"date-time":"2008-12-11T09:35:10Z","timestamp":1228988110000},"page":"294-299","source":"Crossref","is-referenced-by-count":1,"title":["Effects of Minor Increase in Serum Calcium on the Immunoheterogeneity of Parathyroid Hormone in Healthy Subjects and in Patients with Primary Hyperparathyroidism"],"prefix":"10.1159","author":[{"given":"Bo","family":"Ahr\u00e9n","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Anders","family":"Bergenfelz","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"127","published-online":{"date-parts":[[2008,12,5]]},"container-title":["Hormone Research"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/karger.com\/article-pdf\/doi\/10.1159\/000184315","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T09:30:52Z","timestamp":1777627852000},"score":1,"resource":{"primary":{"URL":"https:\/\/karger.com\/article\/doi\/10.1159\/000184315"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2008,12,5]]},"references-count":0,"URL":"https:\/\/doi.org\/10.1159\/000184315","archive":["Portico"],"relation":{},"ISSN":["0301-0163","1423-0046"],"issn-type":[{"value":"0301-0163","type":"print"},{"value":"1423-0046","type":"electronic"}],"subject":[],"published":{"date-parts":[[2008,12,5]]}}}