PTH and neurofibromatosis type 1: This is in accordance to a recent metanalysis showing that bone involvement in NF1 patients seems to be due to a dysregulated bone cellular activity independently from vitamin D. Namely, PTH and bone resorption markers (CTX) resulted elevated, whereas vitamin D, calcium, phosphorous, ALP and osteocalcin levels were not significantly altered in the NF1 patients compared with healthy subjects [39].