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Even though only 2.5% of the population fit the diagnostic criteria for short stature, it is one of the most common reasons for referral to a pediatric endocrinologist. Parents and children alike are worried about the social implications of reduced adult height. Sports activities, stress level, and partner choices are all affected by height.
Boys are more likely than girls to be referred to the endocrinologist for short stature; however, just because a child is considered “short” does not mean that he/she is outside of average, but how does a pediatrician determine the average to which the child is compared?
Types of growth charts
Growth charts are the standard way to measure growth. While older growth charts were controversial, the cornucopia of replacements has firmly established the growth chart as an integral tool in the pediatrician’s toolbox. Each pediatric visit should include weight, height, and head circumference measurements that are tracked on a standardized growth chart.
Growth charts are accumulated data from thousands of healthy children. These charts are separated by gender, ethnicity, and feeding type (breastfed versus formula-fed). Certain countries have formed their own charts. Separate charts have even been constructed for children with certain conditions (small for gestational age, Turner syndrome, Down syndrome, etc.).
There are two kinds of charts: standard and reference. Standard charts refer to the ideal growth for that child’s demographic, in the absence of over-nutrition, malnutrition, and other stressors.
Reference charts are population-based charts. For example, an American reference chart would have higher values for weight and BMI than less-developed countries. Picking the correct growth chart for your patient is important in order to assess how the child compares to his or her peers.
Growth velocity (growth rate)
These growth charts not only show how the child’s height, weight, and head circumference compares to their peers, but serial measurements show the child’s growth velocity. Normal velocity by percentage is showed on the chart by the S-shaped curves.
When a child crosses those percentage lines, this indicates a change in velocity. Normal variations in change in growth velocity are catch-up growth, catch-down growth, and constitutional delay of growth and puberty.
Catch-up growth refers to a smaller infant who “catches up” to his or her peers in height and weight. Similarly, catch-down growth is when a larger infant’s growth slows to match his or her peers. A child with a constitutional delay of growth and puberty would display slower growth throughout childhood. This child would start puberty later and then reach a normal adult height.
Checking for constitutional growth delay
The human hand develops with puberty, not with age. If a hand X-ray is normal for a younger child, they may just have delayed puberty.
Other labs you might get:
- CBC: Check for anemia, evidence for chronic illness
- ESR: IBD, other chronic illness
- Thyroid studies: TSH, if high then free T4
- Chem 7: Renal diseases
- TTG/IgA: Celiac disease
- IGF1 and IGFBP3: Growth hormone deficiency
Definition of Short Stature
With an understanding of growth chart percentiles and growth velocity, the definition of short stature is simple: two standard deviations below average, which is the 3rd percentile on a growth chart, with normal growth velocity.
Even though growth hormone deficiency is rare, this hormone is often used therapeutically for short stature.
If the eventual total height is likely to be under 5 feet and the child is growth hormone-deficient, consider growth hormone replacement.
- Standard of care in diseases like Turner’s
- Daily shots
- Extremely expensive
- Controversial “!”
- Very little benefit if not growth hormone deficiency
Function and deficiency of growth hormone
The easiest way to remember the functions of the growth hormone (GH) is to remember the symptoms of GH deficiency. GH is important in childhood growth. An infant with GH deficiency will be born a normal size, but then be very short in childhood.
In fact, the only symptoms of GH deficiency that would be evident at birth would be hypoglycemia, as GH raises blood sugar levels by interfering with insulin, and micropenis.
Since GH increases protein production and use of fat stores, a child with GH deficiency will become overweight if not treated. Moreover, GH promotes the growth of bone and cartilage. Children with a GH deficiency have immature bones. This bone growth delay leads to a small maxilla and prominent forehead. Clinically, the look of a GH-deficient patient – short, overweight, small jaw, prominent forehead – is described as having a “cherub appearance”.
|Growth hormone function||Symptom of growth hormone deficiency|
|Raises blood sugar levels
Interferes with insulin
|Bone and cartilage maturation||Immature bone and cartilage
|Fat utilization and protein production||Increased subcutaneous fat|
|Increases IGF-1||Low IGF-1 (used for diagnosis)|
Regulation of growth hormone
GH is secreted by the anterior pituitary gland in response to the secretion of the growth hormone-releasing hormone (GHR). The secretion of GH is also stimulated by ghrelin and enhanced by adrenergic stimulation, hypoglycemia, starvation, exercise, early stages of sleep, and stress.
Thyroid hormone is also required for the secretion of GH, so children with hypothyroidism also have short stature. GH secretion is inhibited by somatostatin and somatotropin-releasing inhibiting factor and decreased by hyperglycemia and beta-adrenergic stimulation.
GH peaks in the middle of the night, which makes it difficult to measure. GH stimulates the production of IGF-1, which is used to measure GH levels. IGF-1 is associated with postnatal growth and is altered by several disease states, including malnutrition, chronic renal and liver disease, hypothyroidism, and obesity.
Etiologies of Short Stature
In the Utah Growth Study, it was found that, out of 555 children with short stature, only 5% had a true endocrine disorder; therefore, it is important to be familiar with the vast number of etiologies of short stature. The most common cause for short stature is variants of normal growth patterns, such as constitutional delay or genetic (short parents).
- Constitutional delay of growth and puberty
- Genetic (familial short stature)
- Genetic (e.g. isolated GH deficiency)
- Hypothalamic or pituitary issues (e.g. pituitary agenesis, trauma)
- Neoplasm (e.g. Langerhans cell histiocytosis, pituitary or hypothalamic tumors)
- Acquired (e.g. CNS infection, head trauma, CVA, hydrocephalus, autoimmune diseases, amphetamine treatment for hyperactivity)
Other endocrine causes
- Glucocorticoid excess
- Poorly controlled diabetes mellitus
- Untreated diabetes insipidus
- Congenital adrenal hyperplasia
- Laron dwarfism
Syndromes of short stature
- Turner syndrome
- Noonan syndrome
- Trisomy 21
- Trisomy 18
- Bardet-Biedl syndrome
- Prader-Willi syndrome
- Osteogenesis imperfecta
- Lysosomal storage disease
- Fetal alcohol syndrome
- Left-to-right shunt
- Heart failure
- Cystic fibrosis
- Disorders of swallowing
- Hepatic disorders
- Sickle cell anemia
- Renal tubular acidosis
- Chronic uremia
- Connective tissue diseases
- Juvenile idiopathic arthritis
- Chronic infections
- Hereditary fructose intolerance
- Poor nutrition
- Iron deficiency
- Zinc deficiency
- Cerebral palsy
- Psychosocial dwarfism
Approach to Short Stature
History taking for short stature
Maternal history and perinatal history should be taken at length to determine if any infections or toxic exposures occurred. Questions about prenatal genetic testing and genetic conditions in the family should also be asked.
Next, examine the child’s growth pattern before 3 years old, as there could be signs of catch-up or catch-down growth. After three years old, children normally do not cross percentile lines. If a chronic disease is suspected, this could give the physician a clue as to when the disease may have begun.
As nutrition is the most common cause for short stature worldwide, history should be taken on the child’s nutritional status and living situation. The patient should report all the food they have eaten in the past 24 hours. This will give the clinician a sample of the child’s eating habits.
A detailed review of systems should be taken to search for any chronic diseases. Take a family history about growth. (e.g. “Was the child’s father shorter than his peers in childhood but reached a normal adult height?”).
Finally, social history is important to evaluate the child’s stress level. Severe stress may cause psychosocial dwarfism. A thorough review of systems should be taken to rule out chronic disease.
- Identify any evidence of growth hormone deficiency or hypopituitarism
- Ask about abnormal development
- Ask about diet
Height and weight measurements
The height and weight should be assessed to determine if they are in the same percentile; changes in height velocity should also be noted. If the height is greater than weight, then the child has a failure to thrive, and the child should have a thorough physical exam with a focus on finding a chronic disease and undergo a full laboratory workup for thyroid, kidney and bowel function before doing a hand X-ray.
If weight is greater than height, then the child has a failure to grow, and the child needs a hand X-ray along with the basic labs. The mid-parental height is an important tool to predict the child’s projected adult height. Calculate the mid-parental height using the following equations:
Mid-parental height (female) = ((father’s height + mother’s height)/2) – 2.5 in (6.5 cm)
Mid-parental height (male) = ((father’s height + mother’s height)/2) + 2.5 in (6.5 cm)
Once the mid-parental height has been calculated, track the child’s percentile on the growth chart and see if their adult percentile height projection matches the calculated mid-parental height. Disparity between those two heights raises suspicion for non-familial causes of short stature.
Physical examination for short stature
After completing the history, a thorough physical exam should include the following:
- Current height and weight.
- Ratio of upper to lower body, which may help diagnose bone dysplasia or Turner syndrome.
- Characteristics of genetic conditions (e.g. single palmar crease for Down syndrome).
- Thyroid size and signs of hypothyroidism.
- Signs of chronic disease in each system (e.g. clubbing for cystic fibrosis).
Symptoms of Turner syndrome:
- Webbed neck
- High arched palate
- Short 4th metacarpal
- Shield chest/wide-spaced nipples
Initial workup of short stature:
- Complete blood count with differential to rule out hematologic disorders and infection.
- Basic metabolic panel to rule out renal pathologies, metabolic disorders and diabetes insipidus.
- Liver function test to rule out liver disease.
- Celiac panel (if suspected).
- Folate and carotene levels to assess nutritional status.
- Urinalysis and urine pH to rule out renal infections and renal tubular acidosis.
- ESR to check for a chronic inflammatory state.
- TSH (if hypothyroidism is suspected).
Bone age as a diagnostic tool
Bones grow under the influence of a variety of factors, such as growth hormone. Similarly to growth charts, bone growth has been tracked and recorded in many children in order to be able to assign specific radiographic findings to a child’s age. In other words, the bone age tells the physician how far along the child is in his growth.
The radiologist specifically examines the epiphyseal growth centers to determine the age. All children with a failure to grow should have a hand X-ray. If the child presents with failure to thrive, and had normal or non-specific values, the child should also receive a hand X-ray.
Interpreting bone age results
If the child has normal or near-normal growth velocity and a bone age that matches the child’s chronological age, suspect genetic causes (e.g. familial short stature or Down’s syndrome) or congenital disorders.
If the child has normal growth velocity, but a delayed bone age, suspect constitutional delay of growth and puberty, mild chronic disease, or resolved chronic disease.
If the child has reduced growth velocity and delayed bone age, suspect endocrine disorders, severe chronic diseases, medications, or pathologic delay of puberty. If, after a thorough workup, no specific pathology is found, the child should be diagnosed with idiopathic short stature.
Therapy of Short Stature
Observation and reassurance
Children with familial short stature or constitutional delay of growth and puberty may be treated with observation and reassurance, since growth hormone is expensive and only provides minor gains. Children with this condition usually reach to the lower end of the normal height range.
Counseling is recommended for these children. Some studies show that adults with below-average height experience greater psychological stress, and children may already have psychosocial stressors as a result of their height deficiency.
Growth hormone therapy
Recombinant human growth hormone (r-hGH) is only FDA approved for children below the 1st percentile of height and diagnosed with idiopathic short stature; however, many families who are wealthy request this treatment, and, subsequently, their children are treated.
Children who use r-hGH only have modest gains (1.2 to 2.8 inches above predicted height). Moreover, when compared to the untreated group, children with GH treatment do not have superior psychological health.
The adverse effects of growth hormone include intracranial hypertension, glucose intolerance, and slipped capital femoral epiphysis. While one study found that growth hormone use is associated with bone cancer, this is very controversial. Other studies suggest that this treatment increases the child’s risk of obesity and diabetes mellitus. Growth hormone replacement is quite expensive. Depending on the protocol, the total regiment cost could range from $76,000 to over $250,000.