Treatment of achondroplasia with growth hormone: Six years of experience

We describe die effects of recombinant hGH (r-hGH) therapy for up to 6 y on stature and body proportions of 35 children with achondroplasia (Ach). Con secutive height (Ht) measurements were plotted on disease-specific Ach grow th curves, but age and sex SD scores (SDS) of Ht, sitting Ht, subischial le g length, and Ht velocity were made with respect to Tanner normal standards . r-hGH was administered by daily subcutaneous injections at a median (rang e) close of 30 (15.8-40) U/m(2) per week [0.06 (0.04-0.08) mg . kg(-1). 24 h(-1)]. Patients were treated for 3 (1-6) y from age 2.25 (1.2-9.3) y. Befo re treatment, Ht SDS was -4.6 (-6.5 to -3.24). Treatment caused a significa nt increase in Ht SDS year to year until y 4 (ANOVA F = 46.94; p < 0.01) th at was subsequently sustained with no significant further change (y 5 and 6 versus y 4, p > 0.05). When the response to r-hGH was also expressed as a change in Ht velocity, there was a significant increase in the first year o f therapy that was maintained over subsequent treatment years (ANOVA = 4.28 , p = 0.001). Age was the most important variable accounting for the first- year response in Ht SDS (r(2) = 0.41, p < 0.001), and dose of r-hGH did not influence this. Increments in sitting Ht SDS were greater than subischial leg length SDS (F = 26.25, p < 0.001; F = 9.04, p < 0.001, respectively). r -hGH treatment improved the Ht position of Ach children relative to their n ormal and Ach peers without obvious side effects. A young age at initiation of therapy prevented the characteristic Ht deficit from accumulating. The greater increase in spinal Ht accentuated the existing disproportion. The a ddition of later surgical leg lengthening could offer the possibility of pr oportionate adult stature just within the normal range.