The breast enlargement may last for 3-5 years and regression begins earlier in girls with the onset prior to 2 years of age. There is no association with delay of menarche and abnormal breast development. Follow-up studies have not demonstrated any reproductive problems. On ultrasound of the ovaries, some studies have shown a small cyst in normal sized ovaries. LHRH and FSH are higher than in normal girls but not as as high as those with true precocious puberty.
Bone age is also normal.
Treatment is reassurance and careful observation to make sure that the thelarche is not the first manifestation of precocious puberty. Premature Adrenarche Adrenarche is the presence of pubic hair before 8 years of age in girls and 9 years of age in boys. It may be associated with the development of axillary hair and adult axillary odor. It is a benign condition that requires no treatment. There is premature production of increased amounts of dehydroepiandosterone in the adrenal.