Adding to the debate around vitamin D's effects on skeletal health, researchers have reported the long-term follow-up of two patients with severe vitamin D receptor mutations, who had normal bone mass acquisition and normalization of calcemia around puberty, suggesting that vitamin D might not be essential for skeletal health in adulthood.

Vitamin D plays a pivotal role in calcium homeostasis, and the consequences of vitamin D insufficiency for skeletal health, as well as the importance of its supplementation, are a matter of great interest.
Individuals bearing homozygous vitamin D receptor ( VDR ) defects present with severe hypocalcemic rickets in early infancy due to vitamin D resistance.

Researchers have reported the follow-up of two patients with hereditary vitamin D-resistant rickets ( HVDRR ), focusing on bone mass acquisition and evolution of calcemia.

Patient 1 is a 30-year-old male bearing a homozygous p.Arg30* nonsense mutation in the VDR DNA-binding domain, who presented at 6 months. From 9 years of age, treatment requirement decreased progressively.
Follow-up with DXA showed normal bone mass acquisition.
In adulthood, patient maintains normocalcemia without calcium supplementation and has no signs of bone fragility.

Patient 2 is a 37-year-old female with milder HVDRR and alopecia due to a homozygous p.Gly319Val mutation in the VDR ligand-binding domain.
Around puberty, hypercalciuria and kidney stones were detected, resulting in suspension of treatment.
Follow-up with DXA revealed normal bone mass, and patient maintained normocalcemia without supplementation during gestation and lactation.

In conclusion, the long-term follow-up of HVDRR provides insights into the role of vitamin D in human calcium homeostasis and bone health.
The normalization of calcemia and normal bone mass acquisition despite a permanently dysfunctional VDR suggest that vitamin D might not be essential for skeletal health in adulthood. ( Xagena )

Damiani FM et al, Osteoporos Int 2015; Epub ahead of print

XagenaMedicine2015