What is precocious puberty?
Precocious Puberty means having signs of puberty (pubic hair or breast/testicular enlargement) at an earlier age than usual. There is a wide range of ages at which children normally start puberty. Girls usually develop breasts and then pubic hair between the ages of 8 and 13 years, with menstrual periods starting between 12 to 13; therefore, signs of puberty prior to age 8 in girls are considered early. Boys normally develop testicular enlargement and then pubic hair between the ages of 9 and 14 years. Deepening of the voice and body hair (underarm and facial) typically occurs between the ages of 13 and 16 years. In boys, signs of puberty prior to age 9 are considered early.
Evaluation for the possible development of precocious puberty is important in children known to have a hypothalamic hamartoma. Be on the lookout for signs of sexual development younger than age 8 in girls or age 9 in boys. It is also important for your child’s pediatrician to monitor how quickly they are growing and progressing through puberty, because rapid rates of height gain and skeletal maturation (measured by a left hand x-ray called a “bone age”) may suggest precocious puberty. If precocious puberty is suspected, your child’s doctor may need to do further evaluation by measuring blood levels of different hormones, including estrogen, testosterone, lutenizing hormone (LH) and follicle stimulating hormone (FSH).
What causes precocious puberty in children with hypothalamic hamartomas?
The hypothalamus and pituitary glands in the brain are considered the “master glands” that control many of the body’s functions, including the initiation of puberty. The hypothalamus releases gonadotropin-releasing hormone (GnRH). This hormone stimulates the pituitary gland to release two other hormones, LH and FSH, that stimulate the gonads to produce sex steroids (estrogen in girls and testosterone in boys) leading to the physical changes of puberty. Hypothalamic hamartomas are a well-recognized cause of central precocious puberty; in fact, hamartomas are the most frequent type of central nervous system tumors to cause precocious puberty in very young children. Hypothalamic hamartomas may present with central precocious puberty as the first sign of the disorder, alerting the parents and pediatrician of the possibility of the diagnosis before neuroimaging confirms the presence of a hamartoma. The type of hypothalamic hamartoma lesion that is most commonly associated with precocious puberty is the parahypothalamic type, in which the hamartoma is attached to or suspended from the floor of the third ventricle (1). It is thought that certain types of hypothalamic hamartomas may lead to secretion of GnRH (2) thereby “escaping” the body’s mechanism to inhibit puberty prior to the normal start time. Precocious puberty associated with hypothalamic hamartomas usually presents before 4 years of age and is associated with accelerated linear growth for age, advanced bone age, and pubertal levels of FSH, LH, and estradiol (in girls) and testosterone (in boys).
Treatment and monitoring
If your child has central precocious puberty related to the presence of a hypothalamic hamartoma, the treatment of choice is GnRH agonist therapy, which is both safe and effective (3). The decision of whether to treat central precocious puberty depends on the child’s age, the rate of pubertal progression, their growth rate, and their estimated adult height as determined from the bone age x-ray. In addition, many children are too young to deal with the psychological aspects of early puberty, and by stopping further advances, your child may feel more like his or her friends.
The goal of treatment for precocious puberty in HH is suppression of pubertal maturation and improvement of final height. There are a number of different formulations and dosing regimens for GnRH analog therapy. GnRH analogs may be given by injection monthly, or every three months, or as an implant placed just under the skin of your child’s inner arm every 12 months. During the first 6 weeks of treatment, your child may experience a temporary, slight increase in the symptoms of puberty before the suppression kicks in. For instance, girls may have mood changes, acne, an increase in breast size, and menses, while boys may have an increase in pubic hair and testicular development as well as acne. Other potential side effects include redness and pain at the injection site, and rarely, a sterile abscess. While on treatment with GnRH analog therapy, your child’s endocrinologist will monitor the physical signs of puberty (which would be expected to regress), the hormonal levels (which would be expected to suppress), and growth as well as bone age x-ray. The majority of children with precocious puberty due to hypothalamic hamartomas can be successfully treated with GnRH analog therapy, and both attain a height close to their genetic potential and delay puberty to parallel the development of their peers.
1. Maixner W 2006 Hypothalamic hamartomas–clinical, neuropathological and surgical aspects. Childs Nerv Syst 22:867-873
2. Mahachoklertwattana P, Kaplan SL, Grumbach MM 1993 The luteinizing hormone-releasing hormone-secreting hypothalamic hamartoma is a congenital malformation: natural history. J Clin Endocrinol Metab 77:118-124
3. de Brito VN, Latronico AC, Arnhold IJ, Lo LS, Domenice S, Albano MC, Fragoso MC, Mendonca BB 1999 Treatment of gonadotropin dependent precocious puberty due to hypothalamic hamartoma with gonadotropin releasing hormone agonist depot. Arch Dis Child 80:231-234
Maya Lodish, MD Pediatric Endocrinologist
National Institute of Child Health and Human Development
National Institutes of Health
Building 10-CRC, Room 1-3330
10 Center Drive, MSC 1103
Bethesda, MD 20892