Endocrine Abstracts

Growth hormone deficiency leads to profoundly decreased growth velocity and, when untreated, to pituitary dwarfism. We evaluated growth evolution for one to four years under rGH therapy (0.07 IU/kg/day, subcutaneously) at seventeen idiopathic pituitary dwarves with isolated GH deficiency, 13 boys and 4 girls, with a wide span of age at therapy onset (between 4 and 24 years old). Diagnosis was set subsequent to at least two negative GH stimulation tests. All patients were pre-pubertal, with a bone age below 13 years (Grunlich and Pyle Atlas) but had normal thyroid and adrenal function. Patients were divided into two subgroups: early-diagnosed patients (12 patients younger than 14 at therapy onset) and late-diagnosed patients (5 patients, diagnosed at a chronological age of over 16 years). Growth velocity was significantly increased in the entire group, from 0.33+/−0.07 cm/month before therapy onset to 0.8+/−0.05 cm/month for the whole follow-up period (P<0.0005). Catch-up growth was maximal during the first year of therapy, with a velocity of 1.04+/−0.16 cm/month, which decreased subsequently. Both mean growth velocities for the whole follow-up period (0.99+/−0.08 vs 0.5+/−0.06 cm/month) and for the first year of therapy (1.33+/−0.13 vs 0.61+/−0.09 cm/month) were significantly higher at the early-diagnosed patients (P<0.01), despite present radiographic growth potential. Early therapy onset in isolated GH deficiency is therefore important not only because patients have a smaller height handicap to recuperate in order to enter the normal growth channel, but also – as our data suggest - because growth cartilage seems to loose with age its reaction potential to GH administration in pre-pubertal patients. Our data show, nevertheless, that high-dose rGH therapy is still beneficial in older pre-pubertal GH deficient patients by significantly accelerating growth speed. GH dosage should be diminished to adult substitutive levels and puberty should be triggered therapeutically once growth ceases.