Total pubertal growth and markers of puberty onset in adolescents with GHD: comparison between mathematical growth analysis and pubertal staging methods.

UNLABELLED: Two methods of determining puberty onset (Preece- Baines model 1 (PB1) and Tanner staging) were used to calculate total pubertal growth (TPG) in adolescents with growth hormone deficiency (GHD). PATIENTS AND METHODS: 34 patients (11 girls) met the following inclusion criteria: isolated GHD, >2 years growth hormone therapy prior to puberty onset, regular weight-adjusted GH dosage, known final height (age >21 years or height velocity <0.5 cm/year), no induction of puberty. PB1 was used to define age and height at onset of the pubertal growth spurt ("take-off"). RESULTS: The results (mean +/- SD) were as follows: in girls, mean age at take-off was 9.8 years; 2.0 +/- 1.1 years before breast stage B2. In boys, mean age at take-off was 11.3 years; 1.4 +/- 0.8 years before testes volume >3 ml. Height at take-off was lower than at Tanner stage 2 by 12.4 +/- 7.6 cm in girls and 7.7 +/- 5.3 cm in boys. TPG was thus markedly greater (p < 0.001) using the PB1 method, as compared with Tanner stage2. Peak height velocity was normal. Final height was -0.5 +/- 0.7 SDS in females and -0.4 +/- 0.9 SDS in males. CONCLUSIONS: The method of measuring TPG from take-off is more objective, and has potentially greater implications for GH therapeutics than the Tanner stage method. In our study, 40% of TPG occurred before "breast stage B2" was attained in GHD girls; whereas 23% of TPG occurred before "testes >3 ml" in GHD boys.

On the independence of adult stature from the timing of the adolescent growth spurt.

Longitudinal studies have shown repeatedly that little or no correlation exists between the timing of the pubertal spurt in stature and adult stature (AS). However, the possibility seems to have been overlooked that such near-zero correlations may, at least theoretically, be an artefact resulting from two opposite tendencies that cancel each other out: a hypothetical "biological" tendency for early maturers to end up as slightly shorter adults and a socially induced tendency, resulting from the existence of social gradients in growth, for accelerated maturation to be accompanied by taller A.S. Data of the Wroclaw Growth Study (355 fitted growth curves) were used to see whether making a sample socially more homogeneous produces any increase in the correlation between age at PHV and AS. No such effects were found. Thus the validity of the view is confirmed that genes controlling the timing of the spurt also affect the shape of the growth curve in such a way that the shorter time available for completion of growth in the early maturers is compensated for by a greater intensity of the spurt itself. © 1994 Wiley-Liss, Inc.

Application of growth models in the analysis of pathological growth data: The case of hypophosphatemic vitamin D-resistant rickets.

Growth in height of 16 patients suffering from hypophosphatemic vitamin D-resistant rickets (HR) was analyzed by means of three nonlinear growth models: the Preece Baines function, the JPPS model, and the triple logistic function. The data were purely longitudinal, covering age ranges from childhood to adulthood, with an average of 3 measurements per year. All three models proved to fit the growth pattern of HR patients with the same degree of accuracy as they do for healthy children, indicating that, despite their small height-for-age and their disproportionately short stature, these patients had a quite normal overall shape of their growth pattern. The JPPS model was particularly appropriate to describe the individual growth pattern of these patients, since the fit of this model was quite robust towards the choice of starting values for the numerical least-squares technique, and the model estimated biological variables in a fairly unbiased way. Analysis of the residuals suggested that in 5 of the 16 patients there was evidence of short-term variations in growth rate (mini-spurts), such as have been described in healthy children. © 1993 Wiley-Liss, Inc.