June 6, 2005

New Method of Growth Hormone Dosing Improves Height

A randomized UCLA study found that a new dosing paradigm can improve height outcomes in the treatment of children who have short stature due to growth hormone deficiency and idiopathic short stature.

The groundbreaking study, presented at The Endocrine Society 2005 meeting in San Diego, Calif., challenges traditional approaches to growth hormone (GH) administration based upon weight.

The authors described a new dosing approach based on the serum levels of insulin-like growth factor-I (IGF-I), the growth hormone GH-dependent hormone that mediates the actions of growth hormone on the growth of children.

In the study, Dr. Pinchas Cohen, lead investigator and professor and chief of pediatric endocrinology at UCLA's Mattel Children's Hospital, along with his UCLA colleagues and collaborators from four institutions, randomized pre-pubertal children with growth hormone deficiency or short stature to one of three treatment arms: a conventional dose of growth hormone according to weight, or to one of two dosing arms where the dose was adjusted to achieve an IGF-I level that was either at the mean for age and gender, or at the upper limit of normal.

Study results showed that the change in height in children whose growth hormone dosage was increased to achieve a higher IGF-I level grew 50 percent better than children receiving fixed doses of growth hormone or whose IGF was maintained at the mean. Furthermore, the higher IGF-I arm resulted in a substantial improvement in the growth of both growth-hormone deficiency patients and patients with idiopathic short stature.

"We feel confident that IGF-based growth hormone dosing could become a novel paradigm in treating growth hormone deficiency, resulting in improved height increases for these children. The growth hormone dose targeted to achieve the higher IGF-I level produced especially meaningful increases in height compared to conventional weight-based methods of determining doses," Cohen said. "Also, the dramatic range of sensitivity to growth hormone in the study population substantiated the rationale for IGF-based dosing. This approach has important implications for both the safety and efficacy of GH."

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