Long term follow-up of a 46,XY phenotypic girl with 17alpha-hydroxylase deficiency treated with alternate-day dexamethasone.

We report an 18-year-old 46,XY phenotypic girl who has been on alternate-day dexamethasone therapy for 10 years. The patient was seen at our hospital for right-sided inguinal hernia at the age of 4 years. Biopsy of the herniated gonad showed testicular tissue, and the karyotype of the peripheral lymphocytes was 46,XY. The diagnosis of 17alpha-hydroxylase deficiency was established by the evaluation of adrenal steroidogenesis at the age of 6.1 years when hypertension was clearly recognized, and was confirmed later by the gene analysis of CYP17 which disclosed a compound heterozygote. The growth rate was suppressed during the initial treatment with daily administration of 0.25-0.5 mg dexamethasone. Switching to alternate-day regimen of dexamethasone 0.5 mg/dose improved height velocity. Subsequent addition of low-dose estrogen therapy induced pubertal growth spurt. The blood pressure and adrenal hormone levels remained almost within the normal range throughout the course. Adrenal function was evaluated at the age of 15 years. Plasma ACTH and corticosterone levels were high only just before the next administration, when the plasma dexamethasone concentration should be at the nadir. Since corticosterone possesses glucocorticoid activity and can work as a glucocorticoid reserve, it is assumed that this mode of dexamethasone administration can be a safe treatment for this disorder. We conclude that the patient with childhood 17alpha-hydroxylase deficiency can be safely and effectively treated with alternate-day dexamethasone without interfering with linear growth.