Asthma, growth and inhaled corticosteroids.

Linear growth can be divided into three phases: during infancy it is influenced mainly by nutrition; thereafter throughout childhood it comes under hormonal control; puberty constitutes the third phase. The pubertal growth spurt, which may account for up to 30 cm of linear growth, results from an increase in growth hormone pulse amplitude that is mediated by sex steroids. The rate of growth in childhood, onset of puberty and final height are determined by the impact of a range of environmental factors on genetic potential. These variables and the effect of asthma itself need to be taken into account when assessing the possible effect of inhaled corticosteroids on growth. Many asthmatic children have a slower growth rate than normal children, and a physiological delay in puberty which does not affect final adult height. Prolonged administration of oral corticosteroids retards growth. The mechanism is not fully understood, but may involve an indirect effect on growth hormone secretion following adrenal suppression. Short-term deceleration of growth has been demonstrated by knemometry in children taking inhaled corticosteroids, but there is no evidence of long-term growth suppression with conventional doses of inhaled corticosteroids. Growth should be monitored in children taking over 0.8 mg day-1 of inhaled corticosteroid, but the priority should be to treat the asthma adequately.