Premature thelarche is the onset of female breast development prior to the age of 8 yrs.
4,6) Regardless of cause, sonography shows hypoechoic breast tissue in the subareolar area, similar to that seen in early stages of normal breast development in female adolescents and in premature thelarche (Figure 1B and Figure
The patients whose bone age/chronological age ratio was >1 and in whom pubertal response was obtained to gonodotropin releasing hormone stimulation test were considered central precocious puberty and the patients who did not meet these criteria were considered premature thelarche
Hypothyroidism or premature thelarche
were detected in 2 children.
One case-control investigation of an apparent rise in premature thelarche
in Puerto Rico seen in the late 1970s suggested that soy formula was associated (Am.
Consumption of chicken raised on such hormones was no higher in families with girls experiencing premature thelarche
than in those where girls developed normally.
Polybrominated biphenyls (PBBs) were found to be associated with premature thelarche
in girls who were breast-fed by mothers with high serum PBB levels ([greater than or equal to] 7 [micro]g/L) resulting from exposure to milk from cows given contaminated feed (Blanck et al.
However, when they compared the blood of 41 girls with premature thelarche
with that of 35 who are developing normally, "we did not find pesticides or their metabolites at higher levels," notes University of Puerto Rico chemist Osvaldo Rosario.
2000), the blood samples were taken from children after referral to pediatric clinics, that is, after premature thelarche
had been observed.
Human studies are scarce, but a recently published case-control study examined the association between premature thelarche
(premature breast development) and phthalate exposure among girls 6 months to 8 years of age (Colon et al.
in Puerto Rico: a search for environmental estrogenic contamination.
Puerto Rico has the highest known incidence of premature thelarche