Idiopathic Short Stature

What is idiopathic short stature?

Children whose growth problem cannot currently be diagnosed are said to have idiopathic short stature, which means short stature with no known cause. Despite the great amount of understanding that pediatric endocrinologists have gained about causes of slow growth and short stature, there are still many factors that affect growth that are not yet fully understood. While tests can determine the cause of the growth problem in some children, for many children no clear cause for the growth problem can be found using the techniques available today. Scientists are working to better understand the growth process and the problems that can occur, and in time, they may learn the cause of the poor growth in many more children with idiopathic short stature.

Understanding Idiopathic Short Stature

How is idiopathic short stature diagnosed?

Usually, either you or your child's family doctor or pediatrician have raised a concern about your child's growth. As a result, your child was referred to a pediatric endocrinologist, a doctor who is trained to evaluate hormone problems in childhood. Some of the most common problems that these specialists see in their offices and clinics are related to growth and physical development – too slow, too fast, too much, too little – these doctors are experts in evaluating such problems. The diagram below demonstrates one method that a doctor may use to diagnose idiopathic short stature.

How do I know Humatrope will work for my child's idiopathic short stature?

If you have made the decision to start Humatrope treatment for your child's idiopathic short stature, of course, you want to know what to expect.

Between 1988 and 2001, Lilly ran two studies of Humatrope treatment in approximately 300 children with idiopathic short stature. One study showed that children who received Humatrope injections were on average 1.5 inches taller when they had finished growing than children who did not receive therapy. The other study showed that children grew significantly faster while receiving Humatrope than before they started taking the medication. For the patients in this study whose adult height could be measured, Humatrope-treatment patients were on average 2 to 3 inches taller than they were predicted to be without Humatrope, and most were in the normal adult height range.

Important Information for Patients with Idiopathic Short Stature – In the placebo-controlled study, the adverse events associated with Humatrope therapy were similar to those observed in other pediatric populations treated with Humatrope. Mean serum glucose level did not change during Humatrope treatment. Mean fasting serum insulin levels increased 10% in the Humatrope treatment group at the end of treatment relative to baseline values but remained within the normal reference range. For the same duration of treatment the mean fasting serum insulin levels decreased by 2% in the placebo group. The incidence of above-range values for glucose, insulin, and HbA1c were similar in the growth hormone and placebo-treated groups. No patient developed diabetes mellitus. Consistent with the known mechanism of growth hormone action, Humatrope-treated patients had greater mean increases, relative to baseline, in serum insulin-like growth factor-I (IGF-I) than placebo-treated patients at each study observation. However, there was no significant difference between the Humatrope and placebo treatment groups in the proportion of patients who had at least one serum IGF-I concentration more than 2.0 SD above the age- and gender-appropriate mean (Humatrope: 9 of 35 patients [26%]; placebo: 7 of 28 patients [25%]).

The adverse events observed in the dose-response study (239 patients treated for 2 years) did not indicate a pattern suggestive of a growth hormone dose effect. Among Humatrope dose groups, mean fasting blood glucose, mean glycosylated hemoglobin, and the incidence of elevated fasting blood glucose concentrations were similar. One patient developed abnormalities of carbohydrate metabolism (glucose intolerance and high serum HbA1c) on treatment.

Treatment of idiopathic short stature

Humatrope is indicated for the long-term treatment of idiopathic short stature, also called non-growth-hormone-deficient short stature, in pediatric patients whose epiphyses (the growth plates at the ends of the long bones) are not closed.

Where can I find more information about idiopathic short stature and the help available to me?

• Your health care professional – He or she can answer specific questions.
• The Human Growth Foundation – The Human Growth Foundation helps children and adults with disorders related to growth or growth hormone through education, research, support and advocacy. This non-profit organization functions as a conduit for individuals with questions about their child's development, or adults with inquiries regarding adult growth hormone deficiency. The Human Growth Foundation has more than 20 publications to help educate the public on growth problems and sources of diagnosis and treatments. On its website, the foundation provides a list of groups for parents, teens and adults.
  Toll free number: 800-451-6434
  Internet: www.hgfound.org
  Email: hgf1@hgfound.org
• The MAGIC Foundation – The MAGIC Foundation for Children's Growth offers services to families of children with growth problems, including idiopathic short stature. These services include parent-to-parent networking opportunities, kids' clubs, medical literature in easy-to-understand terms, and more.
  Toll free number: 800-362-4423
  Internet: www.magicfoundation.org
  Email: mary@magicfoundation.org