1. Use of 3- (2,6-dichloro-3,5-dimethoxyphenyl) -1- {6- [4- (4-ethylpiperazin-1-yl) phenylamino] pyrimid-4-yl} -1-methylurea or its a pharmaceutically acceptable salt, N-oxide or solvate for the treatment of X-linked hypophosphatemic rickets (HGH), autosomal dominant hypophosphatemic rickets (ADGR), autosomal recessive hypophosphatemic rickets (ARGR), tumor-induced osteomalacia, hypophosphate transplant syndrome, post-neoplastic syndrome osteoglophonic dysplasia or McCune-Albright syndrome. 2. Use of 3- (2,6-dichloro-3,5-dimethoxyphenyl) -1- {6- [4- (4-ethylpiperazin-1-yl) phenylamino] pyrimid-4-yl} -1-methylurea or its pharmaceutically acceptable salts, N-oxide or MES for the treatment of X-linked hypophosphatemic rickets (HGR), autosomal dominant hypophosphatemic rickets (ADGR) or autosomal recessive hypophosphatemic rickets (ARGR) .3. Use of 3- (2,6-dichloro-3,5-dimethoxyphenyl) -1- {6- [4- (4-ethylpiperazin-1-yl) phenylamino] pyrimide-4-yl} -1-methylurea or its pharmaceutically an acceptable salt, N-oxide or solvate to increase the volume or thickness of the compact substance of the bone when compared with the control or with the volume or thickness of the compact substance of the bone before treatment. 4. Use of 3- (2,6-dichloro-3,5-dimethoxyphenyl) -1- {6- [4- (4-ethylpiperazin-1-yl) phenylamino] pyrimid-4-yl} -1-methylurea or its pharmaceutically acceptable salt, N-oxide or MES to inhibit the expression of FGF23 in the bone or inhibition of the activity of FGF23 in the bone. 5. The use according to any one of paragraphs. 1-4, where 3- (2,6-dichloro-3,5-dimethoxyphenyl) -1- {6- [4- (4-ethylpiperazin-1-yl) phenylamino] pyrimid-4-yl} -1-methylurea is in the form of a monophosphoric acid salt. 6. The use according to any one of paragraphs. 1-4, where 3- (2,6-dichloro-3,5-dimethoxyphenyl) -1- {6- [4- (4-ethylpipe1. Применение 3-(2,6-дихлор-3,5-диметоксифенил)-1-{6-[4-(4-этилпиперазин-1-ил)фениламино]пиримид-4-ил}-1-метилмочевины или ее фармацевтически приемлемой с
