Vitamin B6 status and interferon-γ-mediated immune activation in primary hyperparathyroidism

• Published in: Journal of internal medicine 2012-12, Vol.272 (6), p.583-591
• Main Authors: Christensen, M. H. E., Pedersen, E. K. R., Nordbø, Y., Varhaug, J. E., Midttun, Ø., Ueland, P. M., Nygård, O. K., Mellgren, G., Lien, E. A.
• Format: Article
• Language: English
• Subjects: Aged; anthranilic acid; Biological and medical sciences; Biomarkers; Blood donors; Cardiovascular diseases; Cardiovascular Diseases - etiology; Cardiovascular Diseases - metabolism; Cardiovascular Diseases - prevention & control; Endocrinopathies; Female; gamma -Interferon; General aspects; Humans; Hyperparathyroidism; Hyperparathyroidism, Primary - complications; Hyperparathyroidism, Primary - metabolism; Hyperparathyroidism, Primary - surgery; Immune response; Immunity, Cellular; Immunologic Factors; Inflammation; Inflammation - metabolism; Interferon-gamma - metabolism; Kynurenine - metabolism; kynurenine-to-tryptophan ratio; Longitudinal Studies; Male; Medical sciences; Metabolites; Middle Aged; Monitoring, Immunologic - methods; neopterin; Neopterin - metabolism; Non tumoral diseases. Target tissue resistance. Benign neoplasms; ortho-Aminobenzoates - metabolism; Parathyroidectomy; Parathyroidectomy - methods; Parathyroids. Parafollicular cells. Cholecalciferol. Phosphocalcic homeostasis (diseases); Postoperative Care - methods; primary hyperparathyroidism; Pyridoxal phosphate; Risk Factors; Surgery; Tryptophan; Tryptophan - metabolism; Vitamin B 6 - blood; Vitamin B 6 - metabolism; Vitamin B6
• ISSN: 0954-6820; 1365-2796
• DOI: 10.1111/j.1365-2796.2012.02570.x

Objectives 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. Design/subjects 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. Results 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