Idiopathic short stature

Lore & Background

Idiopathic short stature (ISS) refers to extreme short stature that does not have a diagnostic explanation after an ordinary growth evaluation. The term has been in use since at least 1975 without a precise percentile or statistical definition of 'extreme'. In 2003, Eli Lilly and Company offered a more precise definition when the pharmaceutical company submitted clinical trial data to the U.S. Food and Drug Administration requesting approval to advertise their brand of growth hormone for the treatment of ISS. They proposed a definition of a height more than 2.25 standard deviations below mean, roughly equal to the shortest 1.2% of the population. Other researchers have described a cutoff of 2.0 standard deviations.

Reader's Guide

Idiopathic short stature represents a diagnostic category for individuals with extreme short stature for which no underlying cause can be identified. Its significance lies in the ethical and economic debates surrounding treatment. There is some evidence that hormone treatment may not result in a significant improvement in psychosocial functioning. It is estimated that it would cost US$100,000 or more to treat someone, but might only move them from the first percentile to perhaps the 10th. This raises concerns about whether such treatment would merely shift discrimination to the next most affected percentile. Alternative treatments such as insulin-like growth factor 1 or aromatase inhibitors have been proposed. The condition remains a subject of ongoing discussion in medical ethics and health economics.

Did You Know?

• The term 'idiopathic short stature' has been in use since at least 1975.
• Eli Lilly and Company proposed a definition of height more than 2.25 standard deviations below mean in 2003.
• Treatment may cost US$100,000 or more but might only move a person from the first percentile to the 10th.
• Some researchers use a cutoff of 2.0 standard deviations below mean.