Effects of growth hormone treatment on adult height in severely short children with X-linked hypophosphatemic rickets

Background We recently showed that a 3-year growth hormone (GH) treatment improves linear growth in severely short children with X-linked hypophosphatemic rickets (XLH). It is unknown if GH therapy increases adult height in XLH patients. Methods We carried out a follow-up analysis of a randomized controlled open-label GH study in short prepubertal children with XLH on phosphate and active vitamin D treatment. The changes in SD scores (SDS) of height, sitting height, leg and arm length, and sitting height index (i.e., the ratio between sitting height and height) were analyzed in 11 out of 16 patients followed-up until adult height. Results At baseline, XLH patients showed disproportionately short stature with reduced standardized height (−3.2 ± 0.6), sitting height (−1.7 ± 0.6), leg (−3.7 ± 0.7) and arm (−2.5 ± 0.8) length, and markedly elevated sitting height index (3.3 ± 0.6; each p