Truths and myths about growth

A short stature is not uncommon. In Thailand, between one and five per cent of children are of short stature. Many parents are concerned when their child is relatively short or growing slowly compared to others of the same age. They also worry about their child being bullied or being at a disadvantage in his/her later profession as an adult.
Many factors impact a child’s growth and final adult height. These include:

•  Genetics: A child’s growth is directly influenced and predicted by parental height. The majority of tall parents usually have a tall child. However, genetics is very complicated as some particular traits (extreme height) can skip and/or be expressed in a later generation.
•  Hormones: Several hormones, the growth and thyroid hormones for example, regulate the child’s growth. Children with growth hormone deficiency are small and grow slowly. Sex hormones work in concert with the growth hormone, the thyroid hormone and nutrients resulting in rapid growth during adolescence. The sex hormones also play an important role in the fusion of the growth plates. All children will stop growing after they have finished puberty. Children who enter or complete puberty too early or too late may often experience aberrant growth.
•  Nutrition: Adequate nutrients including energy, protein, as well as vitamins and minerals such as vitamin D, phosphorus, calcium and zinc are essential for a child’s growth. These various nutrients work together to promote growth and help a child to reach his/her genetic height potential. Nutritional deficiencies significantly retard physical growth.
•  Exercise: Exercise in childhood influences growth. Regular exercise or physical activity can promote a child’s growth and stimulate growth hormone secretion. However, excessive strenuous or prolonged exercise can stunt a child’s growth.
•  Absence of chronic illness: Chronic diseases can impair a child’s growth

Regular assessment of your child's growth is the best way to detect short stature and tackle the problem at early stages. Accurately measure your child’s weight, height and compare to the standard growth chart. From birth to the age of five years, the World Health Organisation growth chart is recommended and for the ages over 5 years, the Thai Public Health Ministry’s growth chart.
Parents should be concerned if a child is growing less than the normal growth rate for that age or falling off a normal growth curve.
The normal growth rates are

•  in the first year of life, 25 cm/year
•  in the second year of life, 12 cm/year
•  in the third year of life, 8 cm/year
•  from the age of 3 years to pre-adolescence, 4-7 cm/year
•  during puberty for girls, 7-9 cm/year
•  during puberty for boys, 8-10 cm/year

After a child has completed puberty, the growth plates entirely fuse. At this point, growth has ended and a child reaches his/her adult height.
There are several myths about growth. Some people believe that rope jumping and basketball can make children taller than other kinds of sports. Some believe that children continue growing until the age of 25 years. So far, there is no scientific proof to confirm such beliefs. Social media also spread untrue advertising such as: oral growth hormones, nasal growth hormone sprays, vitamins/nutrients, and massage to accelerate height. Several individuals have become victims of these unrealistic claims. 
The truth is that optimal nutrients, hormones and physical activity (neither too little nor too excessive) maximise final height. There is NO scientific support that oral or nasal growth hormone sprays are effective. The only growth hormone, approved by Thai-FDA for treatment of growth hormone deficiency, comes in injection form and needs to be prescribed by a paediatric endocrinologist. This growth hormone injection helps the growth hormone-deficient child to achieve his or her normal adult height.
The paediatrician, especially the paediatric endocrinologist, can evaluate whether a child is growing normally. If the growth is abnormal or not compatible with genetic potential, blood tests or bone X-ray can be obtained to identify the cause of short stature. More than 40 hospitals across Thailand, public and private, can give advice and provide investigation and treatment for all families.

ASST PROF PRAPAI DEJKHAMRON is attached to the Department of Paediatrics at Chiang Mai University’s Faculty of Medicine.