Growth of patients with congenital adrenal hyperplasia due to 21-hydroxylase in infancy, glucocorticoid requirement and the role of mineralocorticoid therapy.

Background The dose of hydrocortisone therapy required to maintain normal growth in infants with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency is lower than in later childhood. This reflects the presence of excess non-aromatisable rather than aromatisable androgen but there has been relatively little focus on the role of mineralocorticoid therapy. Methods Growth data of infants with CAH due to 21-hydroxylase deficiency (2008-2016) were reviewed and information regarding hydrocortisone and fludrocortisone regimen was collected. Change in height standard deviation (SD) and height velocity standard deviation score (SDS) were analysed during the first year of life. Results Growth data from 13 children (8 M) were analysed. Height (length) declined from a median of -0.69 SD at 3 months to -1.23 SD at 12 months with a reduction in height velocity SDS from 0.02 between 3 and 6 months to -2.22 between 9 and 12 months (p=0.017) despite a hydrocortisone dose at the lower end of the range as recommended in consensus guidelines. The glucocorticoid activity of hydrocortisone and fludrocortisone was negatively associated with growth velocity (r=-0.55; p=0.049) although renin activity was not suppressed. Conclusions Infants with 21-hydroxylase deficiency can be managed with replacement hydrocortisone. The reasons for this paradigm are now understood although our data confirm that the glucocorticoid activity of fludrocortisone needs to be taken into consideration as well.