From the Guidelines
Vitamin D should be given in hypophosphatasia, specifically in the form of active vitamin D (calcitriol or alfacalcidol), in combination with oral phosphorus (phosphate salts), as soon as diagnosis is established in children, and in symptomatic adults to reduce osteomalacia and its consequences and to improve oral health. This recommendation is based on the clinical practice guidelines for the diagnosis and management of X-linked hypophosphataemia, which suggest treating children with overt X-linked hypophosphataemia phenotype with a combination of oral phosphorus and active vitamin D 1. The initial dose of calcitriol is recommended to be 20–30ng/kg body weight daily or alfacalcidol of 30–50ng/kg body weight daily, and the dose should be adjusted according to the improvement of rickets, growth, alkaline phosphatase, and parathyroid hormone levels 1.
In adults, treatment with active vitamin D and phosphate is recommended in symptomatic patients, with a dose range of 0.50–0.75 μg daily for calcitriol and 0.75–1.5 μg daily for alfacalcidol, and 750–1,600mg daily for phosphate (based on elemental phosphorus) 1. The treatment should be individualized, and the dose of active vitamin D and phosphate should be reduced in patients with long-term immobilization to prevent hypercalciuria and hypercalcaemia 1.
Some key points to consider when treating hypophosphatasia with vitamin D include:
- Monitoring of parathyroid hormone levels to avoid secondary hyperparathyroidism
- Regular assessment of renal function to prevent nephrocalcinosis
- Ensuring adequate calcium intake to support bone health
- Adjusting the dose of active vitamin D and phosphate according to clinical and biochemical responses
Overall, the use of vitamin D in hypophosphatasia should be guided by the clinical practice recommendations and individualized to each patient's needs, with careful monitoring of potential adverse effects and adjustment of treatment as necessary 1.
From the Research
Vitamin D in Hypophosphatasia
- Vitamin D is given in hypophosphatasia, as evidenced by a study where a patient with hypophosphatasia was treated with calcium, vitamin D, and risedronate for 2.5 years 2.
- Another study found that vitamin D deficiency occurs in hypophosphatasia patients with a similar frequency as in the general population, and supplementation according to general guidelines can raise serum vitamin D levels without exacerbating the disease burden 3.
- Vitamin D is also used in the treatment of hypophosphatemia, which can be associated with hypophosphatasia, as it helps to improve bone mineralization and prevent deficiency symptoms 4, 5.
- Additionally, vitamin D deficiency or resistance can lead to hypophosphatemia, which is a common feature of hypophosphatasia, and improvement in hypophosphatemia is one of the earliest markers of response to vitamin D supplementation 6.
Key Findings
- Vitamin D supplementation can be effective in raising serum vitamin D levels in hypophosphatasia patients 3.
- Vitamin D therapy can help to correct secondary hyperparathyroidism and improve bone mineral density in hypophosphatasia patients 5.
- Vitamin D deficiency or resistance can lead to hypophosphatemia and impaired bone mineralization, which are common features of hypophosphatasia 6.