Medications for Growth Disorders

by Food and Drug Administration (FDA)

Many homes have pencilled lines on a wall that chart the rapidly rising height of children, and often even the most picky pint-sized eaters will be inspired to chow down if they are told the food will make them "big and strong."

When a child's growth or development goes awry, it often dismays parents and prompts them to seek medical help. Whether or not there is actually a physical abnormality, when a child's growth varies greatly from the average, social and emotional problems may result. A child who is significantly shorter than his or her friends or one who has delayed or precocious (early) puberty, for example, may be shunned or ridiculed by other children.

Several new drugs can set a child's abnormal growth back on track. In the late 1980s, the Food and Drug Administration approved Protropin and Humatrope, two synthetic forms of human growth hormone, to treat children with small stature. These drugs can boost the growth rate of children deficient in the hormone, preventing extremely short adult stature.

(Growth hormone extracted from cadaver pituitaries was used to treat such children before the development of synthetic human growth hormone. But the discovery in April 1985 that some of the natural growth hormone was contaminated by a microbe that causes a fatal brain illness known as Creutzfeldt-Jakob disease prompted officials to stop its use.)

In delayed puberty, it is development of sexual characteristics rather than final height that is impeded. Physicians use sex hormones and their chemical cousins experimentally to boost the growth and development of these "late bloomers." (See accompanying article.)

At the opposite extreme, some children develop adolescent sexual characteristics at a very young age and stop growing much earlier than normal so that they grow up to be short adults. To treat this condition, known as precocious puberty, two synthetic hormones, called histrelin acetate (Supprelin) and nafarelin acetate (Synarel), were approved by FDA in the past two years.

Ethical Dilemmas

Although these treatments may benefit children with extreme cases of short stature, or delayed or precocious puberty, their use in borderline children — those on the short end of the measuring stick, for example, but not rock bottom on the charts — is raising some thorny ethical issues.

Short stature doesn't always stem from a disease, for example, but often is part of the normal variation in height and is inherited from short parents.

Physicians are wary of treating normal short children with growth hormone for merely cosmetic or social reasons, especially since the benefits and adverse effects of the hormone treatments on these children are not fully known. The decision of which children to treat rests with physicians and parents. It cannot wait until the child matures to adulthood and is able to make his or her own decision, since growth hormone is not thought to be effective in full-grown adults.

"Often it isn't the kids who are worried about being short, but their parents," points out pediatric endocrinologist Gilbert August, M.D., of George Washington University. "These parents, who are short themselves, vicariously relive through the child their own failures in high school about not being able to make the team, etc. I've often joked that if you could just do a 'parentectomy' these kids would be fine."

But even without parental pressures, short stature can be costly in our society, which values height. Some scientists cite studies showing success is tied to inches, with taller people making more money or having more prestigious jobs on average than shorter individuals.

Drawing the line between normal growth and development and medical disorder is not always clear-cut. Growth disorders can be difficult to diagnose because of the wide variation in normal growth rates, and researchers are just beginning to tease apart the various hormones and other factors that govern a child's growth and entrance into puberty.

Growth Hormone Deficiency

One of the more challenging growth disorders to diagnose is a growth hormone deficiency. It affects only 15,000 to 20,000 children in this country. Some children with a growth hormone deficiency have normal growth rates the first few years of life. This growth abnormality is suspected if a child is between 3 and 12 years of age and growing less than 2 inches a year for an extended period.

But before diagnosing growth hormone deficiency, physicians first rule out several more common conditions that can temporarily slow growth, including a deficient diet, abnormal digestion, stress, hypothyroidism, diabetes, brain tumor or injury, and chronic illness, such as severe asthma or a kidney disorder.

An inherited tendency to be on the short side of normal, as evidenced by a child's short parents, can also explain a slow growth rate. Children may have delayed puberty, in addition, which can temporarily retard growth. (See accompanying article.)

Once these factors are ruled out, using various blood, cell and urine tests and x-rays, standard growth hormone stimulation tests are usually done. Growth hormone levels are measured in the blood after the child is given certain drugs known to prompt growth hormone secretion.

Low levels of growth hormone in these tests signal a classic growth hormone deficiency. Children's growth hormone levels may hover around the somewhat arbitrary "normal" cutoff point in these tests, however. Whether these children have a true growth hormone deficiency can't be known for certain, especially because growth hormone stimulation tests are not considered precise or sensitive.

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.