Growth and childhood asthma.

Correspondence Growth and childhood asthma Sir, We read the recent article by Dr Balfour-Lynn with interest.1 In this study the prepubertal height centile from a 'distance' chart of each individual child was extrapolated to the adult centile as an assessment of final height prognosis. It is the degree of epiphysial maturation, however, that determines the proportion of growth that has occurred and hence the height potential remaining; only 40% of the children in this study had an assessment of bone age. A further assumption was the use of development of pubic hair as a sign of the onset of puberty. Pubic hair, which is predominantly associated with adrenal androgen secretion, is not necessarily a sign of the onset of puberty. Luxurious development of pubic hair is common in children with absent puberty secondary to hypogonado-trophic hypogonadism or gonadal dysgenesis. Figure 1 of this article depicted the timing of the growth spurt of a boy with asthma coincident with the onset of puberty. One of the characteristics of puberty in boys is that the onset of the spontaneous growth acceleration occurs late in puberty, between genitalia stage 3 and 42 or more accurately at the attainment of a 10 ml testicular volume. Clearly, in Figure 1 the growth spurt was either unrelated to the spontaneous growth acceleration of puberty and perhaps due to 'catch up' growth secondary to effective treatment or the assessment of the onset of pubertal maturation was incorrect. If the former was correct then the growth pattern was not due to delayed puberty; the latter would put the accuracy of the entire study into doubt. The data presented showed a loss of the harmony of normal growth and puberty. and this usually points to an endocrine abnormality.3 Such a longitudinal study should be an important contribution to our understanding of the growth of children with asthma, many of whom have delayed growth and puberty. The data presented and the errors in methodology, however, do not permit the conclusions that Dr Balfour-Lynn has made. Dr Balfour-Lynn comments: It is intriguing to learn from the department made famous by Professor Tanner that children who faithfully follow one of the centile lines on his growth and development charts throughout the whole of their growing life cannot be considered to have grown normally. In this study all 66 children were directly observed to do this up to at least 10 years of …