Inhaled corticosteroid therapy for asthma in preschool children: growth issues.

Although inhaled corticosteroids (ICS) have emerged as the preventive treatment of choice for persistent asthma, few studies have been conducted in infants and very young children that assess the benefits and risks of ICS therapy, particularly with regard to growth. Oral glucocorticoids inhibit growth at multiple levels by blunting pulsatile growth hormone (GH) secretion, decreasing insulin-like growth factor-1 bioactivity, and directly inhibiting new collagen synthesis. Normal childhood growth can be divided conceptually into 3 phases according to primary growth-supporting factors: nutrition-dependent growth of infancy, GH-dependent childhood growth, and sex steroid/GH stimulation of pubertal growth. Susceptibility to glucocorticoid-induced growth suppression appears to increase during periods of transition from one phase to another, particularly in the immediate prepubertal years. Studies using ICS at varying dosages demonstrate the possibility of short-term growth suppression, but long-term studies suggest a negligible effect, if any, on final adult height or bone mineral density. Although certain speculations regarding the safety of ICS use in infants and very young children can be made based on these data, age-specific studies are needed to account for effects of differences in oral versus airway deposition and growth axis resiliency, which may occur in these patients.