Unsuppressed parathyroid hormone in patients with autoimmune/inflammatory rheumatic diseases: implications for vitamin D supplementation

Objectives. To verify if autoimmune/inflammatory rheumatic disease (ARD) patients were more refractory to PTH suppression by 25(OH) vitamin D (VITD). Methods. Data from 105 consecutive ARD patients (including RA, PMR, spondyloarthritis and other CTDs) attending a tertiary-level immuno-rheumatology clinic and 1542 subjects tested at our central laboratory from 2008 to 2010 (controls) were collected. After exclusion of patients with renal failure, primary hyperparathyroidism and hypercalcaemia (n=522), plasma VITD, PTH, calcium and phosphate concentrations were compared between these two groups. Results. Plasma VITD concentrations were