Bone Abstracts

Introduction: Intravenous bisphosphonates (IB) and subcutaneous denosumab (SD) are potent antiresorptive agents widely used in the treatment of osteoporosis, Paget’s disease and metastatic malignancy. Several case reports have identified the risk of life-threatening hypocalcaemia with these treatments, particularly in the context of vitamin D deficiency and further highlighted by recent UKMHRA advice.

Design: To optimise vitamin D status and decrease hypocalcaemia risk, a two-step approach was taken: i) Clear written instructions provided to GPs to check serum 25(OH) vitamin D (25OHD) levels and start oral supplementation (colecalciferol 100 000 units total over 5 days) if 25OHD<50 nmol/l. ii) Provision of standard administration protocol with clear thresholds for 25OHD (>50 nmol/l), corrected calcium (>2.00 mmol/l) and renal function (eGFR>30 ml/min per 1.73 m² for IB).

Results: Prior to the introduction of this protocol (October-December 2011), four (5%) of 84 patients had 25OHD tested before treatment. However, subsequent testing found 41 (49%) with 25OHD< 50 nmol/l and 21 (25%) had 25OHD< 25 nmol/l. One patient was hypocalcaemic (adjusted calcium 1.77 mmol/l), requiring treatment. Following introduction of the protocol (August–September 2012), 78 patients were reviewed: 66 (85%) had 25OHD checked within guideline recommendations, representing an improvement (95%CI) of 80 (77–93)% (P<0.0001). Within this group, 25 patients (32%) had insufficient vitamin D levels of which only 4 (5%) had levels below 25 nmol/l, representing improvements of 17 (2–32) % (P<0.05) and 20 (10–30)% (P<0.001).

Conclusion: Vitamin D deficiency was significantly reduced in our patient population, which may have been explained, partially, by season. However, we demonstrate a significant improvement in the monitoring of vitamin D levels and appropriate oral vitamin D supplementation in line with current guidance.