How should I monitor a patient with osteomalacia for treatment efficacy and potential complications?

Monitoring treatment efficacy in osteomalacia involves clinical and biochemical assessment. Initially, assess symptoms such as bone pain, muscle pain, and proximal muscle weakness to evaluate clinical improvement. Biochemically, check adjusted serum calcium levels to detect ongoing deficiency, hypercalcaemia, or unmasked primary hyperparathyroidism after vitamin D treatment initiation. Serum 25-hydroxyvitamin D (25[OH]D) levels may be checked 3–6 months after starting vitamin D therapy in symptomatic patients, those with malabsorption, suspected poor compliance, or those on potent antiresorptive agents. If 25(OH)D levels remain below 50 nmol/L, assess adherence and consider specialist referral for further investigation. If levels are above 50 nmol/L, advise maintenance vitamin D dosing and lifestyle measures such as safe sunlight exposure and diet to maintain adequate vitamin D status.

To identify potential complications, monitor for hypercalcaemia, which can result from vitamin D toxicity and cause soft tissue calcification, bone demineralisation, and renal or cardiovascular toxicity. If hypercalcaemia is detected, stop vitamin D supplements and arrange further investigation. Consider alternative diagnoses if symptoms persist despite adequate treatment.