GROWTH IN CHILDREN WITH X-LINKED HYPOPHOSPHATEMIC RICKETS

Currently, X-linked hypophosphataemic rickets (XLHR) is most commonly treated with a combination of phosphate and vitamin D, but there is co nflicting evidence about the effects of this treatment on linear growt h. In all, 25 patients with XLHR (current age range, 4.1-22.1 years; m edian, 8.2 years) were studied to determine whether there was any impr ovement in height SDS during treatment. The duration of therapy was 2. 9-15.0 years (median, 5.7 years). Measurements before the age of 2 yea rs or after the onset of puberty were excluded to remove the effects o f measurement difficulties in small infants and of variation in pubert al timing. The growth of these patients was compared with a similar gr oup of untreated historical controls. Patients treated with calcitriol and phosphate for at least 2 years before the onset of puberty (n = 2 2) had a significantly better mean height SDS than the historical cont rols (-1.23 compared with -2.05 for the historical controls; p = 0.02) . Among patients treated with calcitriol and phosphate for at least 2 years (n = 21), the change in height SDS had a positive correlation wi th the duration of therapy (r = 0.51; p = 0.02). The growth of childre n with XLHR treated with combination therapy was thus significantly be tter than that of historical controls.