Sir.—It is possible that I missed something in the article by Tsuru and associates1 in the January issue of AJDC.
The authors gave the so-called Z scores of linear length before and after treatment of patients with hypophosphatemic rickets. This indicates that the patients were 2.2 SDs below the mean at the age of 2 years and 2.7 SDs below the mean at 12 years. In other words, over the span of observations, their short stature has not changed. This is precisely what I have seen over the years with various forms of treatment in this disease. Growth velocity data do not indicate what the eventual height of these children will be. My colleagues Drs Howard, Huse, and Hayles and I2 presented in an abstract our experience treating 16 children for periods from one to seven years with buffered phosphate, ergocalciferol (vitamin D2), or dihydrotachysterol. The
STICKLER GB. Growth Velocity Data and Hypophosphatemic Rickets. Am J Dis Child. 1988;142(1):14. doi:10.1001/archpedi.1988.02150010020009