After 6 months of treatment , both groups had a significantly increased bone age , but the letrozole group had a significantly slowed increase in bone age compared with the control group ( 13.82 0.23 years vs 14.47 0.30 years ; P < 0.05 ) ; compared with the control group , the letrozole group had a significantly increased predicted adult height SD score ( -1.69 0.26 vs -1.91 0.35 ; P < 0.05 ) and a significantly increased T level ( 4.9 0.9 nmol/L vs 4.4 0.8 nmol/L ; P < 0.05 ) .