Dwarfism

Definition

Growth hormone deficiency involves abnormally short stature with normal body proportions. Growth hormone deficiency can be categorized as either congenital (present at birth) or acquired.

Alternative Names

Causes

An abnormally short height in childhood may occur if the pituitary gland does not produce enough growth hormone. It can be caused by a variety of genetic mutations (such as Pit-1 gene, Prop-1 gene, growth hormone receptor gene, growth hormone gene), absence of the pituitary gland, or severe brain injury, but in most cases no underlying cause of the deficiency is found.

Growth retardation may become evident in infancy and persist throughout childhood. The child's "growth curve," which is usually plotted on a standardized growth chart by the pediatrician, may range from flat (no growth) to very shallow (minimal growth). Normal puberty may or may not occur, depending on the degree to which the pituitary can produce adequate hormone levels other than growth hormone.

Growth hormone deficiency may be associated with deficiencies of other hormones, including the following:

• Thyrotropins (control production of thyroid hormones)
• Vasopressin (controls water balance in the body)
• Gonadotropins (control production of male and female sex hormones)
• ACTH or adrenocorticotrophic hormone (controls the adrenal gland and its production of cortisol, DHEA, and other hormones)

Physical defects of the face and skull can also be associated with abnormalities of the pituitary or pituitary function. A small percentage of infants with cleft lip and cleft palate have decreased growth hormone levels.

Symptoms

• Slowed or absent increase in height
• Slow growth before age 5
• Short stature -- below 5th percentile on a standardized growth chart, an adult less than 5 feet tall
• Absent or delayed sexual development in an adolescent
• Headaches
• Excessive thirst with excessive urination
• Increased urine volume

Exams and Tests

A physical examination including weight, height, and body proportions will show signs of slowed growth rate and deviation from normal growth curves.

Tests may include the following:

• Hand x-ray can determine bone age.
• DEXA (Dual Energy X-ray Absorptiometry) can also determine bone age.
• Measurement of growth hormone and associated binding protein levels (IGF-I and IGFBP-3) reveals if the growth problem is caused by dysfunction of the pituitary gland.
• Tests to measure other hormone levels (lack of growth hormone may not be an isolated problem).
• X-ray of head may show problems with the skull, such as small, enlarged, or empty sella or a space-occupying lesion.
• MRI of the head can show the hypothalamus and pituitary glands.

Treatment

Synthetic growth hormone can be used for children with growth hormone deficiency. This treatment requires the assistance of a pediatric endocrinologist. Treatment with synthetic (recombinant) human growth hormone is generally considered to be safe, with rare side effects.

If the deficiency is an isolated growth hormone deficiency, synthetic growth hormone is given alone. If the deficiency is not isolated, other hormone replacement preparations will be required as well.

Outlook (Prognosis)

Growth rates are improved in most children treated with growth hormones, although the effectiveness may decrease with prolonged treatment.

Possible Complications

If left untreated, extremely short stature and delayed puberty will result from this condition.

In the past, some patients acquired Creutzfeldt-Jacob disease

Synthetic growth hormone is used instead and carries no risk of infectious disease.

When to Contact a Medical Professional

Call your health care provider if your child seems abnormally short for his or her age.

Prevention

Most cases are not preventable.

Review your child's growth chart with your physician after each check up. If you child's growth rate is dropping or your child's projected adult height is much shorter than an average height of both parents, evaluation by a specialist is recommended.

Adjusted average height of both parents is as follows:

• For boys:
  • Mom's height plus 5 inches + Dad's height. Divide the end number by 2.
• For girls:
  • Dad's height minus 5 inches + Mom's height. Divide the end number by 2.