Endocrine Abstracts

Background and aim: Achondroplasia (ACH) is one of the commonest skeletal dysplasias affecting 1:15 000–1:40 000 live births. The average attained adult height is 131±5.6 cm for men and 124±5.9 cm for women. Previous studies have shown that the use of rhGH may result in transient increase in the growth rate, but there have been no long-term data regarding adult height. We aimed to study a cohort of patients with ACH and other skeletal dysplasias who have been treated with rhGH and evaluate their response and attainment of adult height.

Methods: We studied 42 patients with skeletal dysplasia who have been treated with rhGH (mean dose 30 U/m² week) over the last 15 years: ACH (n=24), hypochondroplasia (n=3), short limb dysplasias (n=6), SED (n=5) and unclassified dysplasias (n=4).

Results: Patients with ACH (71% male, 29% female) started treatment at a mean age of 3.4±2.5 years (1.2–9.0), with a HtSDS of −1.14±1.5 (−3.30 to 1.86). Mean duration of treatment was 10.2±3.2 years (4–15) for ACH and 9.5±3.8 years (2–14) for other skeletal dysplasias. Growth velocity (GV) during the 1st year (7.8±1.2 cm/year) was significantly higher than the GV observed in the 2nd and 3rd years (5.5±1.5 cm/year and 4.8±0.9 cm/year respectively, P<0.05). 80% of ACH patients have reached final height and 30% had a limb lengthening procedure. Taking into account the height gained by limb lengthening, children with ACH had variable height gain in puberty (8.8±5.5 cm, range 0.2–21.8 cm). At end of growth, they had a change in Ht SDS from −0.89±1.36 to 1.55±0.84 (P<0.05).This difference became non significant once limb lengthening procedures were considered (−0.89±1.36–1.07±0.78, P>0.05).

Conclusions: Patients with ACH treated with rhGH have a more pronounced increase in GV during the 1st year. Final Ht SDS is not significantly different from pre-treatment Ht SDS. The evaluation of patients with other forms of dysplasias is difficult due to small numbers and the lack of disease specific charts.