Narrowband ultraviolet B irradiation increases the serum level of vitamin D 3 in patients with neurofibromatosis 1

The serum vitamin D 3 levels in patients with neurofibromatosis 1 has been reported to be significantly lower than that in control subjects, and the level of vitamin D 3 reversely correlates with the severity of neurofibroma formation. We found that narrowband ultraviolet B ( NB‐UVB ) irradiation increased the serum level of 1,25( OH ) 2 vitamin D 3 in patients with neurofibromatosis 1. The difference in the 1,25( OH ) 2 vitamin D 3 levels between patients who had received irradiation for more than 18 months and those who had no irradiation was highly significant. Time‐course analyses of the serum vitamin D 3 levels in the patients who were enrolled after informed consent revealed that the levels became higher significantly after 6 months of irradiation. It is suggested that NB‐UVB irradiation is effective for increasing the serum level of vitamin D 3 in patients with neurofibromatosis 1, which may be of benefit for skin symptoms such as pigmented macules or neurofibromas.