Medications for Growth Disorders : Part 2

by Food and Drug Administration (FDA)

(Page 2 of 3)

Other children may "pass" growth hormone stimulation tests even though they may have a growth hormone disorder. For example, growth hormone stimulation tests can't detect children who secrete adequate quantities of an abnormal form of growth hormone that is unable to prompt normal growth. Also, some children may secrete normal amounts of growth hormone when stimulated by the tests, but don't make enough of the hormone under normal circumstances. Both types of children may benefit from growth hormone therapy.

It is known that radiation therapy or brain tumors can cause growth hormone deficiency, but in most cases the causes are not known. Decades of experience with growth hormone therapy have shown, however, that it works in nearly all children accurately diagnosed with the condition even if the cause cannot be pinpointed.

Growth hormone therapy is given by injection, either daily or several times per week. Parents are trained to give these injections unless the children feel comfortable doing it themselves. Therapy continues until the end of puberty, when bone growth stops, or sooner, if both family and doctor feel the child has reached an acceptable height.

The sooner before puberty therapy begins, the greater the height that can be achieved. There is no firm evidence tying growth hormone therapy to any significant side effects when it is used properly. Reports that the therapy can boost the likelihood of developing leukemia, or other disorders have not been confirmed, although long-term studies are addressing this.

Giants in the Making

Even less common than growth hormone deficiency is growth hormone excess, which can cause gigantism. One such person with this condition in the 1930s was nicknamed the "Alton Giant," after his Illinois hometown. He reached a height of nearly 9 feet and a 37 shoe size, according to the Life book Growth.

Fewer than 50 such "giants" have been reported in the medical literature. Most owed their amazing growth to pituitary tumors that prompted excessive production of growth hormone. Other symptoms that often accompany pituitary tumors are headaches, dizziness, vomiting, and vision disturbances such as double vision.

Nearly all pituitary tumors can be detected with CT (computerized tomography) scans or magnetic resonance imaging (MRI) scans. Patients with these tumors are treated with surgery, radiation, or an experimental drug that mimics the natural compound somatostatin, which inhibits the release of growth hormone. These treatments can sometimes stem excess growth hormone production and return a child's growth rate to normal.

Excess growth hormone production should be suspected if a child is exceptionally tall and growing unusually fast. The vast majority of such children, however, do not have abnormal growth hormone production, but are merely following in their tall parents' footsteps.

Precocious Puberty

Some children are tall for their age and grow faster than expected because they are undergoing precocious puberty. Although the onset of puberty varies considerably, sexual development before age 8 in girls and age 9 in boys is generally considered precocious puberty. This condition can occur as early as in infancy. About one child of every 10,000 in the United States starts puberty prematurely, according to the National Institute of Child Health and Human Development.

The hormonal changes responsible for early puberty are usually the same ones that trigger normal puberty. The brain secretes pulses of a hormone called luteinizing hormone-releasing hormone (LHRH), which prompts the pituitary gland to release hormones called gonadotropins. These hormones, in turn, stimulate the ovaries and testes to make sex hormones that cause the development of sexual characteristics as well as trigger a growth spurt.

Consequently, children who start puberty prematurely are initially tall for their age. But the sex hormones also cause growth to stop earlier than normal so the children may not achieve their full height potential. Boys may not grow taller than 5 feet 2 inches, and half of the girls do not exceed 5 feet.

The cause of precocious puberty in girls with the condition often is not known. Rarely, early puberty in girls is prompted by tumors, brain disorders, injuries, or infections. Also, in rare cases, girls have hormone-secreting tumors or cysts in the ovaries or adrenal glands that prompt what is known as pseudoprecocious puberty. (Unlike children undergoing true precocious puberty, girls with pseudoprecocious puberty don't ovulate, and boys with the condition don't generate sperm.) Precocious puberty in boys, in contrast, is often caused by brain tumors. The rare boys who undergo pseudoprecocious puberty, in addition, often have tumors in the adrenal glands or the testicles.

Doctors can determine what type of precocious puberty a child has from blood hormone levels and CT or MRI scans of the head, adrenal glands, or sex organs.

Early puberty is inherited in nearly 1 out of 10 boys with the condition. The tendency to start puberty prematurely can be passed directly from father to son, or indirectly from the maternal grandfather through the mother (who does not start puberty early herself) to her son. Premature puberty is inherited in fewer than 1 in 100 girls with the condition.

"Precocious puberty is a problem," points out FDA pediatric endocrinologist Saul Malozowski, M.D., "because a child who experiences it has the sex drive of someone with [adolescent levels] of sex hormones, but lacks the emotional maturity to deal with it."

Because precocious puberty often limits height, and is accompanied by teasing by a child's peers, doctors usually recommend treating the condition. Such treatment aims to halt or even reverse the condition.

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.