The long and the short of it

By
October 29, 2005 21:38

There are many reasons for people to be far shorter or taller than average.




After checking to make sure they have 10 fingers and 10 toes, new parents don't usually pay much attention to their infants' length. But of the 145,000 babies born in Israel every year, 5% are regarded as "small for gestational age" (SGA) - that is, shorter than 47 cm and less than 2.5 kg. Of these, 85% will reach normal size and weight during their first two years, but the rest - about 110 - will not. Of course, many short people cast long shadows when judged by their accomplishments, witness Napoleon Bonaparte and Yitzhak Shamir, Natan Sharansky, writer David Grossman and performers Tzipi Shavit and Danny Sanderson, to name just a few. A Hebrew-language, one-hour documentary about short people (titled Namuch or "Short") was produced and directed recently by Idan Alterman for TV's Channel 2. Alterman, who recalls he was "the shortest kid in class," made the film because he always felt lonely. "I could only hope that someday, someone would make a documentary about people who are shorter than average, and answer the thousands of questions that have tortured and frustrated me, but maybe also made me what I am." SGA MALES will be shorter than 1.62 and females shorter than 1.50 meters when they reach adulthood. Not only are their sub-standard heights likely to make them feel out of place, but they may be a sign of systemic ailments such as hormonal imbalance, hypertension, cardiovascular disease and type II diabetes. In any case, many can be successfully treated for retarded or excessive growth, so the sooner they are diagnosed the better. The journal Psychiatry reported recently that SGA children were 50% more likely thanchildren of normal height to suffer from anxiety and depression when they mature. Researchers at the University of Bristol in the UK studied the data on 5,572 people born in the 1950s and compared their rates of depression with their birthweights, mental development and behavior as children. Another study, published in The Lancet by researchers in Stockholm, followed up adults born between 1973 and 1980, looking for any connection between SGA and suicide during their teen and young adult years. They found that the risk of suicide among adults who weighed less than two kilos at birth was double that of children born at normal weights; those who were shorter than 47 centimeters at birth were also at higher risk for suicide than those who were at least 50 centimeters long. Children experience growth phases at various points during adolescence. Some begin their growth spurts early, while others are "late bloomers." Many parents may be curious to know how tall their child will be as an adult. A study in The Journal of Pediatrics describes an inexpensive and non-invasive way to predict a child's adult height based on sex and growth factors. Lauren Sherar and colleagues from the University of Saskatchewan in Canada and the Faculty of Kinesiology and Rehabilitation Sciences in Belgium assessed height and weight from previous studies of 224 boys and 120 girls aged 8-16 years. "Early bloomers" tend to grow faster and reach their adult height before "late bloomers," they reported. On average, however, girls tend to reach their peak height at 12 years of age and boys at 14 (not for nothing does Judaism determine "womanhood" and the bat mitzva at 12 but "manhood" and the bar mitzva only at 13). The researchers estimated when a child would reach peak height and made their predictions according to each child's age, sex, weight, growth maturity level, sitting and standing height. By adding the child's present height to how many centimeters the child has to grow, the authors were able to predict the final height of boys within 5.4 cm (6.8 cm for girls). Because children can be insecure about their adolescent height, predicting their adult height can improve their social well-being. Parents can calculate this figure by entering information about their child at www.usask.ca/kinesiology/research-index.php. A new 128-page book in Hebrew on endocrinological problems that cause excessive shortness and height is titled Gedilat Yeladim Nemuchim Ugvohim (Growth of Children: The Short and the Tall), and was published by Prolog and written by Prof. Moshe Philip (chief of the endocrinology and diabetes institute at Schneider Children's Medical Center in Petah Tikva) and Dr. Leora Lazar, a senior physician in the institute. The authors suggest adding together the heights in meters of the parents and dividing them by two. Then add 6.5 centimeters for a boy and subtract 6.5 centimeters for a girl to arrive at their child's genetic height potential. A result of +/- 8 centimeters is considered within the normal range. But this formula is no guarantee, as there are numerous other factors - environmental and hormonal - as well as genetic (Turner's syndrome in girls, for example, causes a variety of disruptions, including stunted growth). And the endocrinologists note that they often ask about heights of grandparents, uncles, aunts and siblings to make more accurate predictions and diagnoses. "Normal" heights also vary from country to country. Germans and Scandinavians, for example, are taller than British, Israelis or Japanese. Thus growth curves published in parenting guidebooks should be suited to the country of origin, but Israeli experts use growth curves for boys and girls produced in the US in 1977, based on a study of 7,000 children of diverse ethnic origins that were adopted by the World Health Organization in 2000. The authors note that these graphs are useful only for checking an individual's growth over time, and much less so for comparing children. THE BIGGEST spurts in growth occur in the fetus, during the first two years after birth and during adolescence, while growth is quite stable during the rest of pre-adult life. In Israel, a nation of immigrants from over 100 countries, "normal" heights are much less clear than in ethnically homogeneous countries. The average height of children in countries located at higher altitudes is shorter than those born at lower altitudes. To monitor growth patterns in children of "irregular" heights, doctors usually refer them for an X-ray of the hand, which shows changes in growth plates over the years and thus the potential for growth (it's also safer to X-ray a child's hand every year or so than his spine, legs or other internal organs). Stunted fetal size can result from many factors besides genetics: They include inadequate blood supply via the placenta, a medical problem in the mother, such as poor nutrition, uncontrolled diabetes or hypertension, or the mother having smoked, drunk alcohol or taken drugs during pregnancy. Pediatric endocrinologists, who are experts in hormones and the glands that produce them, are the specialists who diagnose and treat problems of children's height. Hormones can be proteins, peptides or steroid-like compounds that affect only those tissues and cells that have special receptors keyed in for them. Thus, Philip and Lazar write, the endocrinology system is like a cellular phone network in which calls can be received only by the intended recipients. HUMAN GROWTH hormone is a very important factor in determining a person's height. It is produced by the pituitary gland, located behind an important brain region called the hypothalamus and connected to it by a knot of nerves and blood vessels. Via these vessels it reaches the liver, where it is taken up by receptors. The binding of the hormone to the receptors triggers the release of insulin-like growth factor-1, which reaches the growth plates at the ends of bones and causes cartilage cells to ripen and bones to grow. Thyroxin, produced by the thyroid gland, is also involved, with an inverse relationship between the amount released to the level of hormones released by the pituitary and thalamus glands. Proper nutrition is vital to normal growth, and to help SGA infants catch up with their peers, but the interaction is still not well understood, the authors write. When adolescence begins, the adrenal glands kick into the growth process, as does estrogen in girls and testosterone in boys. When should parents worry about a "short" child? The authors note that if progress is steady, with the child growing a few centimeters a year, parents should not be alarmed. But if there are major differences in growth from year to year, or if a child is eight centimeters shorter (or taller) than the norm, it is worth consulting a pediatrician, who may refer you to an endocrinologist. If sexual maturity begins before eight in girls or nine in boys, consult a doctor. Experts will decide whether short children need growth hormone, which is injected under the skin daily before bedtime (the drug cannot survive the gastric juices in the stomach, and so can't be taken in pill form). It has been approved by the Health Ministry for children aged four and up. Some 100 SGA children currently receive injections of NovoNordisk's Norditropen Simplex - the first approved liquid growth hormone (rather than the powders that had to be mixed with liquid before injection). It is not yet in the basket of health services, however, even though treatment can often result in normal or near-normal height. Children who need it get it either as participants in clinical trials, as donations from voluntary organizations or, if not, at their parents' expense. EXCESSIVE HEIGHT is much less common than excessive shortness, but still exists. When a child is taller than 97% of his or her peers, it is regarded as a clinical condition. Disorders include pituitary giantism (in which the gland produces too much hormone), Marfan syndrome (a genetic condition that Abraham Lincoln reportedly suffered from), cerebral giantism (very rapid growth of the head in the uterus and during the first four years of life, long bones, mental retardation and poor coordination) and aromatase deficiency (lack of an enzyme that turns testosterone into estrogen). Growth rates in such excessively tall children, many of whom would have a significantly shorter life expectancy if left untreated, can sometimes be slowed with the injection of various sex hormones. The authors devote a whole chapter to the psychological aspects of growth disorders. Many such children suffer from teasing, difficulty in sports and lack of social acceptance, especially as teenagers. Some cope by developing skills that give them a positive reputation, such as playing an instrument or excelling at a sport that doesn't require height. Others play up their disability and act as "clowns." But too many withdraw and suffer from loneliness. Parents should always be alert to the first signs of psychological problems in such children and seek help.


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