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Medical Conditions

Premature Thelarche

Michael S. Kappy, M.D., Ph.D.
Chief, Pediatric Endocrinology, The Children's Hospital
Denver, Colorado

What is premature thelarche?

Thelarche means "the beginning of breast development." Therefore, if a girl begins to show breast enlargement at an early age (anywhere from birth to six years), it is called "premature thelarche."

Technically, most cases of early breast enlargement are harmless, and do not progress significantly. They are not the beginning of (continued) breast development. They also are not usually associated with the development of the other physical signs of puberty, e.g., acne, pubic hair, periods, or rapid growth. Therefore, a better term for this condition is infantile, or early, "gynecomastia," which only signifies that one or both breasts are enlarged.


What causes premature thelarche?

Studies of girls with early breast enlargement have not shown elevated blood levels of estrogen or any other abnormality. Occasionally, an ovarian cyst (or cysts) may be seen on a pelvic ultrasound, but this condition also may occur in girls without breast enlargement; therefore, it is not clear if the cyst(s) are secreting enough estrogen to cause the breast enlargement. Some physicians believe that the girls are just temporarily more sensitive to their normal blood levels of estrogen.


Who gets premature thelarche?

There is not one identifiable group of girls who develops early breast enlargement. However, it is a concern if a male infant or a young boy shows breast enlargement.


How does premature thelarche cause disease?

Premature thelarche is not a disease; instead, it is a normal finding in some young girls or female infants. If there are other signs of puberty, then a physician should evaluate the child for the causes of early puberty.


What are the common findings?

The common finding is the enlargement of one or both breasts. In simple premature thelarche, there are no other signs of pubertal development, and the child is growing at a normal-not an increased-rate.


How is premature thelarche diagnosed?

Most commonly, premature thelarche is diagnosed in a female infant or a girl up to three years of age. Occasionally, a girl from three to six years of age will show an enlargement of one or both breasts. However, after age six, the beginning of breast development is actually the beginning of puberty; however, it is a very slow form of development. In addition, girls with early breast development usually do not have early periods.

Typically, the girl has no other signs of puberty, and is growing at a normal, pre-pubertal growth rate, i.e., about two inches a year. Laboratory studies are not usually helpful, since they show low (pre-pubertal) concentrations of estrogen or other hormones that stimulate pubertal development. An x-ray of the hand shows a picture that is normal for the girl's age, and not that of an older girl.


How is premature thelarche treated?

Treatment for early breast development is not necessary; however, the physician and the parents may want to monitor any changes in the girl's breast size.


What are the complications?

Usually, there are no complications associated with early breast development. Since there is a very small chance that the girl is actually starting puberty, it is recommended that both the physician and the parents monitor her.


How is premature thelarche prevented?

Premature Thelarche cannot be prevented. Parents should be sensitive to their children's concerns and encourage communication so as to alleviate anxiety or fears.



Kappy MS, Ganong CS. Advances in the treatment of precocious puberty. Adv Pediatr 1994;41:223-61.

About the Author

Dr. Kappy is a professor of pediatrics at the University of Colorado Health Sciences Center and the Chief of the Pediatric Endocrinology Department at The Children's Hospital in Denver, Colorado.

He was a recipient of the Johns Hopkins University Distinguished Alumnus Award in 1996. His research interest include the treatment of precocious puberty and the effects of growth hormone in growth hormone-deficient individuals.

Copyright 2012 Michael S. Kappy, M.D., Ph.D., All Rights Reserved

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