Diagnosis of Growth Disorders

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Diagnosis

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1. Height and Weight

When a child visits the outpatient clinic for the first time, height and weight are measured, the mid-parental height is calculated, and the target range is determined and recorded on the growth curve. Mid-parental height refers to the average of the parents' heights plus 6.5 cm for boys, or minus 6.5 cm for girls, and the target range is ±8.5 cm for girls and ±10 cm for boys based on this value. If a child's height falls outside this target range, a growth-related disorder may be suspected.

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To evaluate the dynamic aspect of growth, it is necessary not only to measure height and weight once, but also to observe growth velocity, so follow-up observation for at least 6 to 12 months is essential. Bringing annual height and weight measurements recorded in the school health record can help evaluate growth velocity.

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If height is below the 3rd percentile for children of the same age, blood tests and urine tests are performed, and an X-ray of the wrist is taken to measure bone age. If bone age is delayed and there are symptoms and signs that may suggest growth hormone deficiency (such as reduced growth velocity, a history of hypoglycemia and jaundice in the newborn and infant period, etc.), the child is hospitalized for a growth hormone stimulation test.

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2. Bone Age

Bone age is determined by taking a plain X-ray of the left wrist after the neonatal period and comparing it with normal standards. Many factors affect the progression of bone age, and measuring bone age is an important test for classifying the cause of growth disorders and predicting future growth potential to estimate final adult height.

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If bone age is younger than the actual age, there is still room for growth; once age increases and the growth plates close, no further growth occurs. Normally, bone age may be measured as about 1 year younger or older than actual age, so measurement error must be taken into account.

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3. Blood Tests

For children with short stature below the 3rd percentile, basic tests include thyroid function, IGF-I as a screening test to assess growth hormone secretory capacity, and blood tests to evaluate nutritional status. If precocious puberty is suspected, gonadotropin and sex hormone tests are also performed. In short girls, Turner syndrome is possible, so chromosome testing is performed as well.

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4. Growth Hormone Stimulation Test

If growth hormone deficiency is suspected, a growth hormone stimulation test is recommended. Growth hormone stimulation testing must be performed during hospitalization. Findings that suggest growth hormone deficiency include short stature below the 3rd percentile accompanied by reduced growth velocity (4 cm or less per year), delayed bone age, a round face, abdominal obesity, underdevelopment of the jaw, a history of hypoglycemia, and a history of brain injury or brain tumor. These patients should receive growth hormone early.

The growth hormone stimulation test is performed by administering two or more of the drugs that stimulate growth hormone secretion. After vascular access is secured, blood is drawn for about 2 hours at 15- to 30-minute intervals before and after taking the drug that stimulates growth hormone secretion.

Because blood glucose can suddenly drop sharply during the test, it requires special attention from medical staff and guardians. If the growth hormone concentration secreted during either of the two growth hormone stimulation tests is 10 ng/mL or higher even once, it is normal. If the highest growth hormone concentration among the repeated measurements never exceeds 10 ng/mL, it is considered growth hormone deficiency. Growth hormone deficiency is confirmed when both growth hormone stimulation tests show results consistent with deficiency.

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5. Imaging Tests

If the growth hormone stimulation test strongly suggests growth hormone deficiency, or if an organic lesion of the hypothalamus or pituitary gland (tumor, congenital malformation) is suspected, brain magnetic resonance imaging (MRI) may be performed.

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So far, I have explained the diagnosis of growth disorders.

In the next part, we will look at the treatment of growth disorders.

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Source: Korea Disease Control and Prevention Agency National Health Information Portal

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