CHILDRENS AND GROWTH PROBLEMS

In-Depth

How is “normal” growth defined?

Measured in height, “normal” growth is described as growth of:

• 0 to 12 months - about 10 inches. Growth during this phase is primarily a function of nutrition.
• 1 to 2 years - about 5 inches. From the age of 1, hormonal factors play an increasingly important role in your child’s growth.
• 2 to 3 years - about 3 1/2 inches a year
• 3 years to puberty - about 2 inches a year. There is minimal difference in growth seen in boys and girls until puberty, which results in an average height difference of 4 to 5 inches between the sexes.

What causes growth problems?

Growth problems can be caused by a number of factors, including genetics, hormonal disorders, systemic illnesses and poor absorption of food. Causes of growth problems usually fall into the following categories:

• Familial short stature, a tendency to follow the family's inherited short stature (shortness).
• Constitutional growth delay, also known as delayed puberty. A child with this condition enters puberty later than average, but is growing at a normal rate. Most of these children tend to eventually grow to about the same height as their parents.
• Illnesses that affect the whole body, also called systemic or chronic illnesses, or illnesses that affect the digestive tract, kidneys, heart or lungs.
• Malnutrition. Constant malnutrition prevents a child from growing as tall as she could; a well-balanced diet generally prevents or corrects this. Malnutrition is the most common cause of growth failure around the world.
• Severe stress
• Endocrine (hormone) diseases, such as diabetes or a lack of thyroid hormones, which are necessary for normal bone growth.
• Syndromes (genetic disorders). Growth problems may be a feature of syndromes such as Cushing's syndrome, Turner syndrome, Down syndrome, Noonan syndrome, Russell-Silver syndrome and Prader-Willi syndrome.
• Growth hormone deficiency. A child with this growth disorder has a problem with the pituitary gland (small gland at the base of the brain) that secretes several hormones, including growth hormone.
• Congenital (present at birth) problems in the tissues where growth occurs.
• Intrauterine growth restriction (IUGR). This condition results from a fetus’s slow growth within the uterus. The baby is born smaller in weight and length than normal, in proportion to his short stature.
• Chromosome abnormalities. Having too many or too few chromosomes can result in health problems, including problems with growth.
• Skeletal abnormalities. There are more than 50 bone diseases that affect height and growth, many of which are genetic. The most common is achondroplasia, a type of dwarfism in which the child's arms and legs are short in proportion to his/her body length. The head is often large and the trunk is normal-sized.
• Precocious puberty. This growth disorder is characterized by an early onset of adolescence in which a child is tall for his age initially, but due to rapid bone maturity, growth stops at an early age and the child may be short as an adult.
• Genetic conditions. There are a few genetic conditions that result in tall stature, where other health problems are also present.
• Idiopathic. There are several growth disorders that are idiopathic, meaning that there is no known cause for the growth problem.

What are the symptoms of a growth problem?

The primary symptom that may indicate a growth problem is when a child grows less than two inches a year after his second birthday. Other symptoms may include:

• slow development of physical skills, such as rolling over, sitting up, standing and walking
• delayed social and mental skills
• delayed development of secondary sexual characteristics in adolescence

GROWTH DISORDER

About Growing

Children grow. It’s part of being a child, and we all expect that as they grow older, children will "grow up" - getting taller as the years go by. What happens when your child doesn't grow as you'd expect?

As a parent you may have these questions:

• Why isn't my child growing taller?
• When is the "growth spurt" going to happen?
• What should I do if I have concerns? Whom should I contact?
• Can anything be done?

In this section, we hope to answer the questions above as well as discuss:

• What is normal growth?
• What can affect a child's growth
• Evaluating growth

What is normal growth?

There is a wide variation in what is considered normal growth in childhood. For example, at two years of age, the normal range is from 33 to 37 inches for boys and 32 to 37 inches for girls; at five years, from 40 to 47 inches for both boys and girls; at 10 years, from 51 to 59 inches for boys and 50 to 59 inches for girls, and at 15 years, from 60 to 72 inches for boys and 59 to 68 inches for girls.

How is growth measured?

Regular, accurate measurements of weight and height are an important part of a child's health care. In infancy, length and weight are regularly checked at visits to the doctor. During early childhood, measurements are usually taken about twice each year, and more frequently if there is anything unusual about a child's growth.

Throughout the child's school years, it is helpful to obtain accurate measurements at least once a year. A variety of devices and equipment can be used to measure height and weight. Doctors and nurses generally use an instrument called a stadiometer, to obtain accurate height.

To determine whether your child is growing normally, your doctor will compare your child's growth to that of other children of the same age and sex. Growth charts showing the averages and normal ranges for height, weight, weight-to-height ratio, and head circumference of children at different ages are used to evaluate your child's growth over time.

Height is shown on the vertical edges of the growth chart, and age is shown along the bottom of the chart. The curved lines are called percentiles. These percentile lines represent the data collected from a large group of children in a national survey, expressed in percentages, so they represent the average growth for children across the nation at different ages

As an example of how to understand these charts, let's say a child's height is at the third percentile - this means that out of 100 children of the same age and gender, 97 are taller and only two are shorter. Children typically grow along a certain percentile line from the toddler years on. If a child begins to move downward away from his or her percentile on the growth chart, this could be cause for concern and requires investigation, no matter how tall he or she is.

Overall, the normal range for height is generally considered to be between about the third and the 97th percentiles. This means that about 94 percent of people (children and adults) are in the normal height range, 3 percent are taller and 3 percent are shorter. It should be noted that the normal height range differs from one country to another. For example, people in the Netherlands tend to be much taller than people in Japan.

A different type of chart, called a height velocity chart, is used to record and evaluate a child's growth rate or how fast a child is growing. The speed of growth is very fast in the first three years of life. But from around three years of age, until about nine or 10 years of age, the speed of growth slows down a little more each year.

Then, at puberty, there is a rapid increase in growth rate - the pubertal growth spurt -during which the speed of growth usually doubles. By regularly measuring height, weight and speed of growth, your child's doctor will be able to determine if your child's growth is following a normal pattern.

What affects growth?

Many factors influence growth

Growth varies with age. Many factors influence how much and how rapidly a child grows, and how tall he or she will be as an adult. Some of these factors can be controlled and others cannot.

• Heredity
• Hormones
• Alterations in Growth
• Other causes

Heredity

Heredity (the genes we inherit from our parents - our genetic potential) is one of the most important factors influencing a child's growth. Height varies among different ethnic groups, among different families within the same ethnic group, and even among members of the same family. There is a relationship between the height of a child and the height of the child's parents. In general, if a child has a tall parent, he or she is likely to be taller than average as an adult. If one parent is shorter than average, the child may be shorter than average as an adult. The genetic influence on height is usually well established by the time a child is two years old.

The expected approximate adult height of a child can be estimated based on the height of the parents. By averaging the mother's height and the father's height (adjusted for the sex of the child), one can come up with a "target height" (also known as mid-parental height) for the child - the average height he or she would be expected to reach as an adult.

Target height for a girl

• Convert the height of each parent into inches (for example, 5 feet, 10 inches = 70 inches).
• Subtract 5 inches from the father's height - this is the father's "adjusted height."
• Add the father's adjusted height to the mother's actual height.
• Divide the total number of inches by 2.

The result represents the daughter's target height.

Example

• Father's height is 70 inches and mother's height is 63 inches.
• 70 inches - 5 inches = 65 inches (father's adjusted height).
• 65 inches 63 inches = 128 inches.
• 128 inches divided by 2 = 64 inches.

The target height for this couple's daughter is 64 inches, or 5 feet, 4 inches.

Target height for a boy

• Convert the height of each parent into inches (for example, 5 feet, 3 inches = 63 inches).
• Add 5 inches to the mother's height - this is the mother's "adjusted height."
• Add the mother's adjusted height to the father's actual height.
• Divide the total number of inches by 2.

The result represents the son's target height.

Example

• Father's height is 70 inches and mother's height is 63 inches.
• 63 inches 5 inches = 68 inches (mother's adjusted height).
• 68 inches 70 inches = 138 inches.
• 138 inches divided by 2 = 69 inches.

The target height for this couple's son is 69 inches, or 5 feet, 9 inches.

This formula is helpful in estimating your child's adult target height. But it is also important to realize that it is possible for a normal individual's height to vary by up to 4 inches either above or below the target height once growth is complete.

Nutrition

A child's growth, both in height and weight, is also influenced by diet. A well-balanced, age-appropriate diet that includes carbohydrates, protein, fats, vitamins and minerals can have a positive affect on how well a child grows. Children who receive an inadequate amount of calories or nutrients may grow poorly; improving the diet of these children may improve growth.

However, there really is no "average" diet that is best for all children. A child's specific dietary requirements vary with age, physical activity level, and other factors. If you have questions about your child's diet, discuss them with your child's doctor.

Additional measurements of your child's head circumference, arm and leg lengths or other body parts, may also be obtained. A careful examination will be performed to check for any signs of congenital conditions (conditions present at birth), chronic illness or hormone deficiencies.

Hormones

Hormones are the chemical messengers of the body. They are released from glands and circulate in the blood, affecting everything from growth and metabolism to blood pressure and mood. Almost all hormones affect growth to some extent, but some have particularly important roles in your child's growth.

Growth hormone is essential for growth. It is made by the pituitary gland (located at the base of the brain), then released into the bloodstream, where it travels to the body's tissues. Here it stimulates production of another hormone important for growth, known as insulin-like growth factor I, or IGF-1. Growth hormone works to stimulate growth in large part due to its effect in producing IGF-1.

Thyroxine (thyroid hormone) is produced in the thyroid gland, located at the base of the neck. It plays an important role in brain development and growth during childhood, and affects metabolism at all ages. Babies who are deficient in this hormone must be treated with thyroid hormone replacement from the newborn period to ensure normal growth and brain development.

Androgens are male-type sex hormones. "Weak" androgens are produced by the small triangular adrenal glands located above the kidneys, and "strong" androgens are made by the testes (male sex glands) in boys. In girls, androgens are also produced in smaller amounts by the adrenal glands and ovaries (female sex glands). Androgens trigger the development of hair in the armpits and genital regions of both boys and girls at puberty. Testosterone, made by the testes, is the most important androgen for boys; it is responsible for the sexual development and maturation that occurs during puberty.

Estrogens are female-type sex hormones, produced mainly by the ovaries. Estrogens trigger breast development and the sexual maturation process that results in menstrual periods. Boys also produce low levels of estrogens in their testes.

Together, androgens and estrogens interact with growth hormone to cause the characteristic "growth spurt" seen at puberty.

Cortisol is another important hormone produced by the adrenal glands. It helps maintain normal blood pressure and blood glucose. Cortisol is released into the bloodstream at higher levels in response to physical stresses such as infection, fever, injury, surgery and severe emotional stress.

Insulin, which is produced in the pancreas, helps the body use carbohydrates (sugars and starches) for energy. When insulin levels are insufficient, diabetes may develop.

Hormone Deficiency or Excess

Thyroid hormone deficiency

The thyroid gland, located at the base of the neck, produces thyroid hormones that have a direct effect on growth and metabolism.

Hypothyroidism, or insufficient secretion of thyroid hormones, may result in slowing of growth.

Hypothyroidism that develops during childhood usually develops slowly, often making diagnosis difficult. A decrease in the speed of growth may be one of the earliest signs of the condition. Some other symptoms of hypothyroidism include dry skin and hair, fatigue, constipation and weight gain. Blood tests can confirm a diagnosis of hypothyroidism. Treatment consists of providing thyroid hormone in the form of tablets given daily.

Excessive cortisol

The adrenal glands, located above the kidneys, produce a number of hormones, including an important hormone called cortisol. Cortisol affects many processes in the body, such as glucose production, fat storage and helping the body cope with stress. When above-normal amounts of cortisol are released by the adrenal glands, many processes and organs in the body are affected. In childhood, one consequence of excessive cortisol may be inhibition of growth. Other symptoms may include fatigue, muscle weakness, weight gain, easy bruising and thinning of the skin.

Detailed testing is required to diagnose excessive cortisol production, and treatment varies according to the cause of the excess cortisol production.

High doses of cortisol-like medications are sometimes required to treat severe conditions such as asthma or arthritis. This can also cause a slowing of growth.

Growth hormone deficiency

The pituitary gland normally produces growth hormone and releases it into the bloodstream. Growth hormone deficiency is a condition in which the pituitary gland produces less than the normal amount of growth hormone, which may result in slow growth, growth disorder, and disturbances of metabolism.

There are a number of possible reasons for poor growth hormone production in childhood. For example, there may have been improper formation of the hypothalamus (the region of the brain that controls the pituitary gland) or pituitary gland itself before birth.

Head injuries, brain tumors, and brain damage due to disease, infection or radiation can also cause poor functioning of the pituitary gland. In many cases, detailed testing will be needed to find the cause of the subnormal growth hormone production.

Alterations in growth

Normal variations

Changing patterns of growth during infancy

For a variety of reasons, a child may be born smaller or larger than would be expected based on the physical size of the parents and other family members (the family's genetic potential). When this happens, the child may show a growth pattern called "catch-up" or "catch-down," depending on the difference between size at birth and expected size. This means that the child's length or height may cross over one or two percentile lines upward or downward, then stabilize once it reaches the percentile appropriate for the genetic potential. This is generally a normal pattern during the first two years or so of life.

Constitutional growth delay

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Constitutional growth delay (also known as constitutional delay of growth and puberty, or constitutional delay of growth and adolescence) refers to a fairly com on variation of the growth process in which growth occurs more slowly than average.

Such children are often the smallest in their class at school. The physical changes of puberty and the pubertal growth spurt occur later in children with constitutional growth delay, around ages 13 to 14 for girls and 15 to 16 for boys. These children are often referred to as "late bloomers." There may be a history of a similar growth pattern in one or more family members. This delayed growth and development may cause some emotional stress for the child; if so, medical or psychological therapy may be helpful.

Other causes of growth disturbance

Turner syndrome

Turner syndrome, a genetic alteration due to a partial or complete absence of one X chromosome in girls, is one of the most common causes of extreme growth disorder in girls. Affected girls usually fail to enter puberty and may have a number of other medical conditions, such as heart or kidney problems. Any condition that is present at birth, such as Turner syndrome, is called a congenital condition. Other examples of congenital conditions include heart defects, skeletal (bone) abnormalities and alterations of chromosomes.

Idiopathic growth disorder

The term "idiopathic" growth disorder is used to describe growth disorder for which there is no known, identifiable cause. However, children with idiopathic growth disorder likely have another cause for their poor growth for which there is currently no known medical explanation. General health in these children is usually good. However, they tend to have lower than average blood levels of IGF-1.

Evaluating growth

Medical history (child and family)

A detailed medical history, including information about the pregnancy and birth, growth during infancy, illnesses, appetite, diet, medications and home environment, may provide the doctor with clues about the reasons for your child's growth disorder or slow growth.

As discussed previously, a child's height is influenced by the heights of the parents. Overall, children from small families tend to be shorter than average as adults. Because heredity (genetic potential) plays a significant role in determining height, the medical history will include information about family members. The heights of the child's parents and the growth patterns of siblings are valuable pieces of information.

It may be helpful to get information from the child's grandparents about anything unusual in the parents' growth patterns, especially the ages at which the parents went through puberty.

Your child's doctor will perform additional evaluations, since other factors - such as treatable medical conditions - also influence growth.

Growth charts

As discussed earlier, the growth chart is an important tool used to determine if a child has a growth problem. By plotting a child's measurements on a growth chart over time, a doctor can determine if a child is growing normally or not. If a child's height falls downward across the percentile lines, he or she fails to grow over a period of time, is much shorter than other children of the same age or is much shorter than would be expected based on the parents' heights, tests may be required to determine the cause.

Physical examination

During a detailed growth evaluation, measurements of your child's weight and height will be obtained. These are plotted on the appropriate growth charts for comparison with normal ranges. It is also helpful if you are able to provide the doctor with any other measurements taken during your child's life - for example, your child's "baby book" or the measurements from the back of the bedroom door!

Bone Age Evaluation

Your doctor may obtain an x-ray of your child's left hand and wrist - called a bone age x-ray - to evaluate the maturity of his or her bones.

The x-ray is compared with a series of standard x-rays of children at different ages to determine your child's bone maturity. Using this x-ray, a child's growth potential can also be determined - that is, how much remaining growth he or she has left. As with all growth measurements, there is a wide range of normal development. Having a bone age that is somewhat younger or older than a child's chronological age (or "calendar age" - the actual age since birth) is not unusual. However, if the bone age is extremely advanced or delayed, this may suggest an underlying growth problem. The bone-age evaluation is generally used along with the physical examination and growth charts to obtain a comprehensive picture of a child's growth and maturity.

Laboratory tests

Blood samples may be taken to look for evidence of any medical problems that can cause growth disorder or slow growth. These tests help your child's doctor determine if chronic illness, poor nutrition, bowel disorders or hormone deficiencies are affecting growth.

Blood Tests for Growth Hormone Deficiency

• Binding protein levels (IGF-I and IGFBP-3) blood tests to show whether the growth problem is caused by the pituitary gland
• Blood tests to measure the amount of growth hormone levels in the blood
• Blood tests to measure other levels of hormones the pituitary gland produces
• GHRH-arginine test
• Growth hormone stimulation test
• Insulin tolerance test

Other Exams and Tests to Diagnose Growth Hormone Deficiency

In addition to blood tests, your doctor may perform some additional exams and tests to help diagnose growth hormone deficiency.

• A dual-energy x-ray absorptiometry (DXA) scan measures your bone density.
• An MRI of the brain may be taken so your doctor can see the pituitary gland and hypothalamus.
• Hand x-rays (typically of the left hand) can also help show your doctor your bones: Shape and size of bones change as a healthy person grows. Your doctor can see bone abnormalities with this x-ray.
• X-rays of the head can show any problems with the bone growth of your skull.