Bone remodeling indices and secondary hyperparathyroidism in celiac disease

To determine the prevalence of hypovitaminosis D and secondary hyperparathyroidism (SHPT) and to assess bone turnover by using markers of bone formation and resorption in celiac disease (CD).

Forty-three patients with CD were investigated: group 1, newly diagnosed celiacs (n = 19); group 2, treated celiacs responding histologically to a gluten-free diet (n = 16); group 3, refractory celiacs, unresponsive to a gluten-free diet and immunosuppressive therapy (n = 8). Serum was drawn for intact parathyroid hormone (PTH), 25-hydroxyvitamin D [25(OH)D], ionized calcium (Cai), total alkaline phosphatase (AP), and biochemical markers of bone formation: procollagen I carboxyterminal propeptide (PICP) and osteocalcin (Oc). Urinary indices of bone resorption, deoxypyridinoline (DPD), pyridinoline (PyD), and hydroxyproline (OHP), were measured in a 2-h fasting urine. In 22 patients, computerized tomographic scan for bone mineral density (BMD) was performed.

The prevalence in groups 1, 2, and 3, respectively, of hypovitaminosis D (< 50 nmol/L) was 58%, 25%, and 88%, and the prevalence of SHPT (> 5.4 pmol/L) was 25%, 19%, and 25%. Bone resorption markers were significantly elevated in all groups, and bone formation indices were elevated in the newly diagnosed celiacs compared with a group of healthy adults. Low BMD (T-score greater than -1 SD unit) was found in 68% of patients assessed; 36% of patients had a T-score greater than -2.5 SD units.

Hypovitaminosis D and SHPT are common in newly diagnosed and refractory celiacs but are less common in those who respond to a gluten-free diet. Newly diagnosed patients have a high bone turnover state with elevation of both bone formation and resorption indices. Those with refractory disease demonstrate a remodeling imbalance with high bone resorption.