Lee Chung Horn
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 Pituitary Disorders

 

SHORT STATURE AND DELAYED PUBERTY

Parents are often concerned about their children's growth, especially if they seem to be shorter than other children that are the same age. While there are many medical causes for being short and having poor growth, including growth hormone deficiency, hypothyroidism, Turner syndrome, inflammatory bowel disease, and kidney problems, most children who are short are normal. They may have genetic short stature or a constitutional growth delay.

What normally happens

Children normally grow at a rate of about 23-28 cm/year in early infancy (birth to 12 months) and this then decreases to about 7.5 - 13 cm/year in later infancy (1 - 3 years). Many children between the ages of 6 and 18 months move up or down on their growth percentiles, but by 24 months, most children follow their growth curve and stay on the same percentile or growth channel.

In early childhood (3 years to puberty) they will then continue to grow at a rate of about 4.5 to 7 cm/year, up until the time just before they begin puberty, when their growth will slow to about 4 cm/year. Growth then accelerates again as they hit their peak growth velocity in puberty, to about 8-9 cm/year for girls and 10.3 cm/year for boys. Growth then slows again in girls to about 7 cm/year after menarche (the first menstrual period) until they reach their adult height. Boys and girls usually continue to grow until they are 16-18 years old, but this depends on when they started puberty.

Among the influences on a child's growth is his overall genetic potential for growth, which can be determined from his parents' heights, his nutritional status, and the presence of any chronic medical problems.

Children with short stature are usually below the 3rd or 5th percentile on their growth chart for their height. But just as important as where they are on or below the growth chart is what their growth velocity or rate of growth has been each year.

Tests

Tests commonly performed to evaluate the growth of a child with short stature include determining a bone age, which is the chronological age of your child's bones. This is determined by taking an xray, usually of his left wrist and hand. If your child's bone age is much less than his chronological or real age, then there is probably still room for his bones to grow after the age that you would normally expect him to already stop growing.

Other tests can include blood tests to check for hypothyroidism (Free T4 and TSH), growth hormone levels (usually by checking IGF-1 and IGF BP3 and with an insulin tolerance test), complete blood counts, blood chemistries to check for kidney and liver disease), and sometimes a karyotype to look for chromosomal abnormalities (especially in girls who may have Turner syndrome).

If the above tests are normal, or if your endocrinologist doesn't think that testing was even necessary (which is often the case for many short children), then your child's rate of growth can just be closely followed every 3-6 months, with a further evaluation being performed if he does not continue to have a normal rate of growth.

Another normal condition that can cause short stature is a constitutional delay in growth. These children, although short, have a normal growth velocity or rate of growth and will usually have a delay in starting puberty, and possibly a prolonged slowdown in growth that is usually present in children just before they begin puberty. They will usually also have a bone age that is much less than their chronological age, showing that there is room to grow and that they will continue growing even after other children of the same age have stopped growing. Because of the extra room and time to grow, children with constitutional delay usually have a normal adult height.

Many parents are worried about growth hormone deficiency in their short children. Growth hormone is required for normal growth, and children with growth hormone deficiency are short, often look younger than their chronological age, and they can be chubby with their weight higher than their height. While they will usually have a delay in their bone age, like children with a constitutional delay, children with growth hormone deficiency will have a slow rate of growth and they will have a growth curve that falls away from the the normal growth curves (unlike other normal causes of short stature which have a normal rate of growth and a growth curve that runs parallel to the growth chart).

Treatments for growth hormone deficiency include growth hormone replacement. This is done by giving daily injections. Other conditions for which growth hormone is currently being successfully used include Turner syndrome, chronic renal failure and Prader-Willi syndrome.

Delayed Puberty

Puberty is said to be delayed when symptoms do not appear by age 13 for girls and age 14 for boys. Delayed puberty can be hereditary; the late onset of puberty may run in the families. However, delayed puberty may also be due to chromosomal abnormalities, genetic disorders, chronic illnesses, or tumors that damage the pituitary gland or the hypothalamus, which affect maturation.

What are the symptoms of delayed puberty?

Indications that a child may be experiencing delayed puberty is the noted lack of puberty symptoms. The following are the most common symptoms of delayed puberty. However, each child may experience symptoms differently. Symptoms may include:


Girls:

lack of breast development by age 13

more than five years between breast growth and menstrual period

lack of pubic hair by age 14

failure to menstruate by age 15

Boys:

lack of testicular enlargement by age 14

lack of pubic hair by age 15

more than five years to complete genital enlargement


How is delayed puberty diagnosed? 

In addition to a complete medical history and physical examination, diagnosis of delayed puberty may include:

blood tests (to check for chromosomal abnormalities, measure hormone levels, and test for diabetes, anemia, and other conditions that may delay puberty)

x-ray - a bone x-ray of the hand or wrist may be performed to determine bone maturity.

computed tomography scan (Also called a CT or CAT scan.) - a CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.

magnetic resonance imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.

Treatment for delayed puberty depends on the cause of the problem. Often, when the underlying cause is treated, puberty proceeds normally. If the delayed puberty is due to heredity, no treatment is usually necessary. In some cases, treatment may involve hormone therapy to stimulate the development of secondary sexual characteristics, or surgery to correct an anatomical problem.


 

Copyright of Lee Chung Horn Diabetes & Endocrinology 2009