Vitamin B6 status and interferon-γ-mediated immune activation in primary hyperparathyroidism
Article first published online: 5 AUG 2012
© 2012 The Association for the Publication of the Journal of Internal Medicine
Journal of Internal Medicine
Volume 272, Issue 6, pages 583–591, December 2012
How to Cite
Vitamin B6 status and interferon-γ-mediated immune activation in primary hyperparathyroidism J Intern Med 2012; 00: 000–000, , , , , , , , (Institute of Medicine, University of Bergen, Bergen; Hormone Laboratory, Haukeland University Hospital, Bergen; Department of Heart Disease, Haukeland University Hospital, Bergen; Department of Surgery, Haukeland University Hospital, Bergen; Institute of Surgical Science, University of Bergen, Bergen; Bevital A/S, Bergen; Laboratory of Clinical Biochemistry, Haukeland University Hospital, Bergen, Norway
- Issue published online: 20 NOV 2012
- Article first published online: 5 AUG 2012
- Accepted manuscript online: 3 JUL 2012 08:18AM EST
- kynurenine-to-tryptophan ratio;
- primary hyperparathyroidism;
- vitamin B6
Primary hyperparathyroidism (PHPT) has been associated with low-grade inflammation and elevated risk of cardiovascular disease (CVD). In inflammatory conditions, interferon-γ (IFN-γ) activity is enhanced and a decreased circulating concentration of vitamin B6 is often observed. Such changes in IFN-γ activity or vitamin B6 levels have been associated with increased incidence of CVD. The aim of the study was to investigate systemic markers of IFN-γ-mediated immune activation, such as neopterin, the kynurenine-to-tryptophan ratio (KTR) and kynurenine pathway metabolites, as well as B6 vitamers in patients with PHPT.
A total of 57 patients with PHPT and a control group of 20 healthy blood donors were included in this study. PHPT patients who responded positively to parathyroidectomy were followed for 6 months. Forty-three patients participated in the longitudinal study in which blood samples were taken at inclusion and 1, 3 and 6 months after surgery.
Plasma concentrations of the B6 vitamers pyridoxal 5′-phosphate (PLP) (P = 0.007) and pyridoxal (P = 0.013) were significantly lower in the patient group compared to healthy control subjects. An increase in the KTR indicated that the kynurenine pathway of tryptophan metabolism was altered in PHPT patients (P = 0.015). During the initial 6 months after surgery, levels of PLP (P < 0.001) and anthranilic acid (P < 0.001) increased significantly, whereas neopterin decreased (P = 0.018).
The results of this study demonstrate altered levels of vitamin B6 and the KTR in PHPT patients, both of which may reflect cellular immune activation. These abnormalities should be considered in relation to the increased risk of CVD previously observed in patients with PHPT.