Osteoporosis-Calcium/Vitamin D — SCE Endocrinology MCQ

Correct answer: B — Total calcium intake ~1200 mg/day and vitamin D 800-1000 IU/day

A total calcium intake of around 1200 mg/day (diet plus supplement if dietary intake is inadequate) with vitamin D 800 to 1000 IU/day is the standard adjunct to bone-protective therapy in osteoporosis, ensuring adequate substrate for bone mineralisation and correcting the vitamin D deficiency that is common in this age group. This dosing reflects UK guidance from the National Osteoporosis Guideline Group and NICE CKS, which advise assessing dietary calcium intake first and supplementing only the shortfall, alongside colecalciferol to maintain adequate 25-hydroxyvitamin D status. Bisphosphonates and other antiresorptive agents require adequate calcium and vitamin D to work safely and effectively; giving them without correcting deficiency risks hypocalcaemia and reduces fracture-prevention efficacy. This combination is therefore recommended as baseline supportive therapy for essentially all patients started on treatment for osteoporosis unless dietary intake is already sufficient. Why the other options are wrong: A. Calcium 500 mg and vitamin D 200 IU: both doses are substantially subtherapeutic, well below the levels shown to support bone mineralisation and vitamin D sufficiency, and would not correct common deficiency in older postmenopausal women. C. No supplements with bisphosphonate: bisphosphonates depend on adequate calcium and vitamin D to be effective and safe; omitting these risks hypocalcaemia and blunts the antifracture benefit, so co-supplementation is standard unless dietary intake alone is confirmed adequate. D. Calcium 2000 mg and vitamin D 4000 IU routinely: these are excessive doses associated with risks of hypercalcaemia, nephrolithiasis, and a possible increase in cardiovascular events with high-dose calcium, and are not the recommended routine regimen. E. Vitamin D only without calcium: vitamin D alone does not provide adequate substrate for mineralisation and has not been shown to reduce fracture risk without adequate concurrent calcium intake. Key point: Osteoporosis treatment requires ensuring total calcium intake of about 1200 mg/day and vitamin D 800 to 1000 IU/day as the supportive baseline alongside, not instead of, bone-protective drug therapy.

Reference: NICE Clinical Knowledge Summaries, Osteoporosis - prevention of fragility fractures, Management: calcium and vitamin D supplementation, https://cks.nice.org.uk/topics/osteoporosis-prevention-of-fragility-fractures/