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[Efficacy of letrozole in treatment of children with congenital adrenal hyperplasia due to steroid 21-hydroxylase deficiency].

OBJECTIVE
To assess the efficacy of letrozole in treatment of children with congenital adrenal hyperplasia (CAH) due to steroid 21-hydroxylase deficiency (21-OHD).


METHODS
Twenty eight children, including 19 boys and 9 girls aged 4-10y, with CAH due to 21-OHD were enrolled in the study. At the first six months of study, all children received conventional treatment with hydrocortisone or fludrocortisone, then letrozole was added to original regimen. The height velocity (HV), difference between bone age and chronological age (BA-CA), height standard diviation score based on bone age (HtSDS BA), predicted adult height (PAH), Tanner phase, sex hormone, and possible adverse reaction were evaluated and compared between those before and after letrozole treatment.


RESULTS
After 6 months of letrozole treatment, there was significant deceleration of HV, but it would recover soon. There was significant increase of HtSDS BA after 12 months of letrozole treatment ( P < 0.05 or P < 0.01), and significant changes in BA-CA after 18 months of letrozole treatment ( P < 0.05). PAH of female children was significantly increased during letrozole treatment ( P < 0.05), whereas PAH of male children was significantly increased 18 months after letrozole treatment ( P < 0.05). Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels were significantly increased, but did not meet the diagnostic criteria of central precocious puberty. Estradiol was significantly decreased ( P < 0.01), but no changes in testosterone level was observed. During 24 months letrozole treatment, no hirsutism, severe acne, headache, bone pain, obesity, hypertension, rash and other adverse reactions were observed.


CONCLUSIONS
Letrozole can delay bone maturation and improve PAH, which can be used with conventional treatment for children with CAH due to 21-OHD, especially for those with high BA and low PAH.