P081 Is it necessary to test vitamin D prior to zoledronate or denosumab treatment?

Abstract

Background/Aims Prior to each treatment of zoledronate (ZA) or denosumab, it is routine clinical practice to test for vitamin D. If vitamin D levels are low, patients must be started on replacement therapy prior to treatment. Other studies suggest that osteoporosis patients not taking vitamin D supplementation are likely to have subtherapeutic vitamin D levels. Awaiting vitamin D levels can delay timely treatment and organising these tests is labour intensive. In this service evaluation, we examined whether patients could have been treated empirically with vitamin D without testing. Methods We included all 542 patients from the New Cross Hospital osteoporosis treatment clinic lists between November 2021 to June 2022. The only patients excluded were those not taking ZA or denosumab. Data collected included demographics, medication history, and vitamin D levels. Vitamin D levels were measured as follows: <15 nmol/L: severe deficiency, 15-30 nmol/L: deficiency, >30-50 nmol/L: insufficiency, >50-250 nmol/L: adequate, >250 nmol/L: potential toxicity. Results 484 patients were included of which 88.6% were female. The mean age was 76.8. 90.0% were either on vitamin D and calcium supplementation, or on vitamin D supplementation alone. Of these patients on supplementation, vitamin D levels were adequate in 79.8%, insufficient in 7.8%, deficient in 0.4%, severely deficient in 0.2% and not available for the remaining patients. Of those not on supplementation, vitamin D levels were adequate in 45.9%, insufficient in 16.2%, deficient in 10.8% and severely deficient in 4%, and not available for the remaining patients. None of the patients had toxic levels of vitamin D. On contacting the 3 patients prescribed vitamin D supplementation but with deficient or severely deficient vitamin D levels, 2 were not taking the supplements and 1 was taking alfacalcidol (which is not measured in the standard trust vitamin D test). Therefore, of those patients taking vitamin D supplementation as prescribed, their vitamin D levels were all above 30 nmol/L. Conclusion This service evaluation therefore supports an approach of not testing vitamin D levels in patients who are due to receive either ZA or denosumab and are taking vitamin D supplementation. A small number of patients taking vitamin D supplementation still had insufficient levels of vitamin D; therefore, it could be recommended to treat all patients on vitamin D supplementation with a short course of high does vitamin D prior to ZA or denosumab treatment. In addition, any patients not taking vitamin D supplementation could also be treated with a course of high dose vitamin D prior to treatment without testing vitamin D levels. This will ensure safe levels of vitamin D and timely treatment of osteoporosis. This will save time and money and reduce waste. Disclosure J. Keasley: None. C. Stevens: None. A. Kumar: None. H. Sapkota: None.