Vitamin D levels in patients with primary hyperparathyroidism; a follow-up study after parathyroidectomy

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 199-237-Disorders of Parathyroid Hormone & Calcium Homeostasis
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-199
Monika Christensen*1, Yngve Nordbø2, Jan Erik Varhaug1, Gunnar Mellgren3 and Ernst Asbjorn Lien4
1University of Bergen, Bergen, Norway, 2Haukeland University Hospital, Bergen, Norway, 3Institute of Medicine, Bergen, Norway, 4Haukeland Univ Hosp, Bergen, Norway
Primary hyperparathyroidism (PHPT) is caused by an autonomic production of parathyroid hormone (PTH) from the parathyroid glands. Treatment of PHTP is surgery removing the glands overproducing PTH. PTH influences the metabolism of vitamin D, and may change the metabolic ratio between 1,25-dihydroxyvitamin D (1,25(OH)2D) and 25-hydroxyvitamin D (25(OH)D). The aim of the study was to investigate serum levels of 25(OH)D and 1,25(OH)2D in patients with PHPT as well as changes in the vitamin D metabolites after parathyroidectomy. The study included 61 patients with PHPT operated at Haukeland University Hospital, Bergen, Norway. 40 patients were followed longitudinally and blood samples were drawn at one, three and six months after parathyroidectomy. Exclusion criteria for participating in the longitudinal study were persistence of elevated PTH-levels. At inclusion median level of 25(OH)D was 57.0 nmol/L, rising to 87.0 nmol/L six months after surgery. Levels of 25(OH)D increased significantly one month after surgery compared to baseline (p<0.001) and between one and three months after surgery (p=0.002). There was no further change in 25(OH)D-levels between three and six months follow-up. Levels of 25(OH)D at inclusion were significantly correlated with levels of 25(OH)D at one, three and six months after parathyroidectomy. Median level of 1,25(OH)2D was 146 pmol/L at inclusion, falling to 107 pmol/L at six months post-operative. A significant fall in 1,25(OH)2D was observed between baseline and one month (p<0.001) and additionally between three and six months after surgery (p=0.021). PTH-levels also decreased between inclusion and one month (p<0.001) and between three and six months of follow-up (p=0.038). The same was observed for the metabolic ratio between 1,25(OH)2D and 25(OH)D, decreasing between inclusion and one month (p<0.001) and between three and six months after surgery (p=0.028). At inclusion positive correlations between 1,25(OH)2D and PTH (p=0.015) and between 1,25(OH)2D and 25(OH)D (p=0.041) were observed. These correlations were not observed six months after parathyroidectomy. In conclusion, we report a change in the metabolic ratio between 1,25(OH)2D and 25(OH)D after parathyroidectomy, decreasing even at six months follow-up. Serum concentrations of 25(OH)D seem to reach stable levels earlier than 1,25(OH)2D and PTH, and initial levels of 25(OH)D were decisive for levels of 25(OH)D one, three, and six months after parathyroidectomy.

Nothing to Disclose: MC, YN, JEV, GM, EAL

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