Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: TUESDAY, July 25, 1995 TAG: 9507250043
SECTION: EXTRA PAGE: 1 EDITION: METRO
SOURCE: BY JANE BRODY
DATELINE: LENGTH: Long
Until so-called recombinant human growth hormone was developed, so little of the natural hormone was available that only children with severe hormone deficiency could be treated.
It still costs $10,000 to $30,000 a year to treat a child, but with recombinant human growth hormone researchers have been able to explore the hormone's effects in children with a full range of growth problems.
Based on their findings, clinical researchers said at a recent meeting of the Endocrine Society in Washington that they now spend most of their time talking parents out of using growth hormone.
Of every 100 children referred to specialists because they are thought to be abnormally short, only five or six meet the criteria for growth hormone treatment.
Dr. Ron G. Rosenfeld, chairman of the department of pediatrics at Oregon Health Sciences University in Portland, said that selecting the right children for treatment was the hardest part of growth hormone therapy and that properly done, the selection process could take six months or more.
This is largely because hormone levels fluctuate widely and no single test accurately reveals the need for treatment.
Growth hormone is produced by the pituitary gland and released in bursts in response to a hormone-like trigger substance from the hypothalamus in the brain.
In about 80 percent of hormone-deficient children, the real problem is an inadequate signal from the brain. The greatest amounts of growth hormone are produced during deep sleep. So unless hormone levels are consistently abnormally low, it can be hard to base a treatment decision on a measurement of growth hormone alone.
Also, it is not growth hormone itself, but rather several growth substances released by the liver and other tissues throughout the body that ultimately stimulate growth.
These substances, called insulin-like growth factors, are being measured more and more to evaluate the need for hormone therapy.
A child deficient in growth hormone will not come close to achieving his or her full genetic potential for height, but administering the hormone daily during the growth years will stimulate skeletal growth.
The child is most likely to reach full potential height if the treatment is begun before school age and continued into or through adolescence.
However, a child who is short but not hormone-deficient and whose biological parents are also short is not going to be turned into a draft pick for the New York Knicks by growth hormone.
Although such a child might grow faster during the first year or so of treatment, the child's final height might not be much affected, if indeed it was affected at all.
Still, there are many conditions for which administration of growth hormone can make a major difference in a child's physical, sexual, social and emotional development.
From 10,000 to 15,000 American children are short because of a growth hormone deficiency, but one in four under treatment is not hormone deficient. These include 5,000 to 7,000 girls with a chromosomal abnormality called Turner's syndrome.
Although their pituitary glands secrete normal amounts of growth hormone, their final height averages only 4 feet 8 inches, and giving them additional hormone - a still-experimental therapy - can stimulate growth to a more normal height.
Others who can benefit from hormone therapy are children with chronic kidney failure, most of whom are abnormally short unless given growth hormone.
Children with other chronic illnesses, such as diseases of the heart, lungs and intestines, may benefit if treatment of their underlying condition does not adequately stimulate growth.
In fact, the first step in assessing an abnormally short child is to determine if growth is inhibited by a correctable underlying physical condition.
Some boys are just late bloomers. They have no apparent disorder other than a delay in their adolescent growth spurt, and most will shoot up near the end of their teen-age years.
But for those whose sexual development is also delayed and who are experiencing psychosocial problems as a result, testosterone therapy, which triggers the release of growth hormone, can be used to accelerate growth and maturation.
Many factors are considered in deciding who should be treated. In addition to the findings of various biochemical tests, factors include being at the bottom of the normal growth curve (the lowest 3 percent for height), showing signs of delayed skeletal development and maturation, and being seriously psychologically or socially impaired because of being short.
A child thought to be abnormally short and perhaps developmentally delayed should be evaluated by a pediatric endocrinologist.
Crucial to the treatment decision is assessing how fast the child is growing. Is the speed of growth consistent and within a normal range? Is the child's growth rate slowing down when it should be steady or increasing?
Learning the answers can take months of accurate height readings done by a doctor using a tape measure, not by parents, whose measurements may be inconsistent.
Another useful measurement compares the child's arm span with body length. In normal growth, the distance from finger tip to finger tip when the arms are straight out from the sides should be within two inches of the child's height.
However, children who are short because their parents are short are not considered appropriate candidates for growth hormone therapy, said Dr. Alan Rogol of the University of Virginia in Charlottesville. Such children should be given growth hormone only as part of a clinical study, he said.
by CNB