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Osteomalacia — SCE Rheumatology MCQ

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EasyMetabolic Bone DiseaseOsteomalaciaSCE Rheumatology

A 62-year-old woman presents with pelvic bone pain and proximal muscle weakness. Investigations show a serum 25-hydroxyvitamin D concentration of 12 nmol/L, mild asymptomatic hypocalcaemia, raised alkaline phosphatase and raised parathyroid hormone. Renal function is normal and there is no evidence of malabsorption. Pelvic radiographs show Looser zones in the pubic rami. What is the most appropriate treatment?

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Correct answer: E — Oral cholecalciferol loading then maintenance, with calcium replacement

This is vitamin D-deficiency osteomalacia: the very low 25-hydroxyvitamin D, hypocalcaemia, raised alkaline phosphatase, secondary hyperparathyroidism and pubic-ramus Looser zones indicate defective bone mineralisation. Treatment is oral cholecalciferol replacement using a loading course followed by maintenance therapy. Calcium should also be replaced because she is hypocalcaemic, with biochemical monitoring. Calcium alone does not correct the underlying vitamin D deficiency. Bisphosphonates and denosumab are antiresorptive treatments for osteoporosis, not treatments for osteomalacia, and can aggravate hypocalcaemia if mineral deficiency is uncorrected. Teriparatide is likewise not first-line treatment for nutritional osteomalacia. Looser zones are characteristic pseudofractures rather than, strictly, a pathognomonic finding.

Reference: Electronic Medicines Compendium, Fultium-D3 20,000 IU capsules, Summary of Product Characteristics, sections 4.1–4.4, updated 2025. https://www.medicines.org.uk/emc/product/3659/smpc