Yearly stepwise increments of the growth hormone dose results in a better growth response after four years in girls with Turner syndrome. Dutch Working Group on Growth Hormone.

Abstract

To optimize the growth promoting effect of growth hormone (GH), 65 previously untreated girls with Turner syndrome (TS), chronological age (CA) 2-11 yr, were randomized into 3 dosage regimen groups: A, B, and C, with a daily recombinant-human GH dose during 4 study years of 4-4-4-4, 4-6-6-6, and 4-6-8-8 IU/m2 b.s. The first GH dosage increase in groups B and C resulted in a significantly higher mean height velocity (HV) compared with constant dose group A. During the third year, when the dose was raised again only in group C, mean HV was significantly higher in groups B and C than in group A, and in group C compared with group B. In year 4 only group C mean HV remained significantly higher than group A. The pattern of change in HSDSCA (Dutch-Swedish-Danish Turner references) was identical; however, in year 4 mean delta HSDSCA in group B also remained significantly higher than group A. After 4 yr GH treatment, the following was determined. 1) The mean delta HSDSCA was significantly higher for groups B and C compared with group A, but not significantly different between groups B and C. 2) Although significantly higher compared with estimated values for untreated Dutch girls with TS, bone maturation of the GH treated girls was not significantly different between groups. 3) It was positively related with the degree of bone age (BA) retardation at start of study and negatively with baseline CA. 4) Both the modified Index of Potential Height (mIPHRUS) and a recently developed Turner-specific final height (FH) prediction method (PTSRUS), based on regression coefficients for H, CA, and bone age, showed significant increases in mean FH prediction, without significant differences between groups. PTSRUS values were markedly higher than the mIPHRUS values. Dose dependency could be shown for the area under the curve (AUC) for GH, but delta HSDSCA was not linearly related with AUC. Baseline GH binding protein (BP) levels were in 84% of the cases within the normal age range; the decrease in mean levels after 6 months GH was not significant. Mean insulin-like growth factor I (IGF-I) and IGFBP-3 plasma levels increased significantly, without significant differences between groups. delta HSDSCA during GH was dependent on IGF-I plasma levels at baseline and during the study period, beta-0.002 and beta-0.0004. Thus, a stepwise GH-dosing approach reduced the "waning" effect of the growth response after 4 yr treatment without undue bone maturation. FH prediction was not significantly different between treatment groups. Irrespective of the GH dose used, initiation of GH treatment at a younger age was beneficial after 4 yr GH when expressed as actual cm gained or as gain in FH prediction, but was not statistically significant when expressed as delta HSDSCA over the study period.

Early treatment with GH alone in Turner syndrome: prepubertal catch-up growth and waning effect

“…The choice of the most appropriate GH doses to be employed at the start of treatment and during the subsequent years is a greatly debated issue (2,5,11,15). According to our results, an initial dose of 1.0 IU/kg per week seems to be sufficient to induce a striking acceleration of HV, at least in young girls and throughout the first year of treatment.…”

“…Although girls with TS are not growth hormone (GH) deficient, GH administration is known to accelerate growth in a dose-dependent way (2). In most girls with TS, puberty has to be induced by estrogen therapy.…”

Normalization of Height in Girls with Turner Syndrome after Long-Term Growth Hormone Treatment: Results of a Randomized Dose-Response Trial

“…Fouryear results were described earlier (5). We now report 7-yr results to compare the long-term growth-promoting effect of GH in childhood between the three dosage groups.…”

“…The median adult height of North European girls with TS is 146.9 cm, being, on average, approximately 20 cm less than their healthy peers (1,2). Although these girls are not GH deficient (3), GH administration accelerates growth in a dose-dependent way (4,5). In many countries, TS is an accepted indication for GH treatment, although the effect of GH on adult height is inconsistent (6 -11).…”

Turner syndrome

“…Two recent studies (10,11) have convincingly demonstrated the importance of higher doses as well as of dose adjustment.…”