Growth hormone therapy helps PWS infants overcome failure to thrive
Study: They gained more lean body mass than those without growth issues
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Five years of growth hormone (GH) treatment allows children with Prader-Willi syndrome (PWS) who are experiencing failure to thrive at the start of treatment to develop similar height-adjusted lean body mass, or non-fat tissue, to those without failure to thrive at GH initiation.
That’s according to a study in The Netherlands, which also showed that children with failure to thrive experience a significantly greater increase in lean body mass in the first year of GH treatment than those without failure to thrive, allowing them to catch up.
“Our findings suggest that GH-treatment has a greater impact on LBM [lean body mass] development in infants with FTT [failure to thrive] than in those without FTT, indicating that the start of GH-treatment should not be delayed until FTT is resolved,” researchers wrote.
The study, “Failure to thrive (FTT) in infants with Prader-Willi syndrome and long-term effects of GH-treatment on FTT,” was published in Hormone Research in Paediatrics.
Long-term effect of growth hormone treatment studied
Infants with PWS, a genetic disease, may experience a wide range of symptoms, including slow growth, low muscle tone, and failure to thrive. Many children with PWS have low levels of GH, which is involved in physical development.
As such, GH therapy, also known as somatropin (sold as Genotropin and Norditropin, with biosimilars available), is commonly used to improve growth and physical strength. However, the long-term effects of GH treatment in infants with PWS who have failure to thrive at treatment initiation are not well understood.
In this study, researchers in The Netherlands evaluated the effects of failure to thrive among infants with PWS before starting GH treatment and examined changes in body composition over five years of treatment.
The study included 166 children (56% boys) younger than 3 years at the start of GH therapy who received the treatment for at least one year. All were followed at the Dutch PWS Reference Centre.
Growth data from birth to 6 months were available for 54 infants. Failure to thrive, defined as weighing substantially less than expected for a child of the same length, was seen in 29% of infants at 1 month, 20% at 3 months, and 16% at 6 months, suggesting that growth difficulties gradually ease during the first months of life.
Infants with failure to thrive had lower lean body mass index
At the start of GH treatment, 20 of the 166 children (12%) had failure to thrive. They started GH treatment at a median age of about 1 year, compared with about 8 months for those without failure to thrive; this difference was not statistically significant.
Infants with failure to thrive had a significantly lower lean body mass index (LBMI), a measure of lean body mass adjusted for height, and a lower percentage of body fat than those without failure to thrive. However, the groups did not significantly differ in birth weight, length, or expected adult height.
Analysis adjusted for age and sex showed that over five years of GH treatment, children who had failure to thrive when treatment began experienced a greater increase in LBMI during the first year compared with those without failure to thrive, despite starting treatment with a lower LBMI.
After five years, LBMI was similar between the groups, while the percentage of body fat remained lower in children who had failure to thrive at treatment initiation.
Among the 20 infants with failure to thrive at the start of treatment, nine began GH during their first year of life and 11 between ages 1 and 3 years.
Those who started treatment earlier were taller but had a lower LBMI, and had similar body fat percentage to those who started at older ages. Still, the LBMI of those starting GH earlier increased significantly more during the first year of treatment than that of those starting GH later in life. After five years, the groups had similar LBMI and percentage of body fat.
Levels of IGF-1 hormone associated with higher LBMI after 5 years
Statistical analyses adjusted for sex, age, genetic subtype, birthweight, and maternal body mass index (a ratio of height and weight) showed that failure to thrive was independently associated with lower LBMI and body fat percentage at the start of GH treatment, but not after five years.
Also, higher blood levels of IGF-1, a hormone that works as key messenger for GH, were significantly associated with a higher LBMI after five years, while higher average GH dose was significantly linked to a lower percentage of body fat after five years.
These findings suggest that infants with PWS who have failure to thrive when starting GH treatment may experience greater gains in lean body mass during the first year of treatment, eventually reaching similar levels to those without failure to thrive.
“Children with FTT at GH-start seem to benefit most from GH-treatment in terms of LBM improvement, resulting in a similar LBM after 5 years of GH-treatment as those without FTT at GH-start,” the team wrote.
They also noted that the results highlight the importance of monitoring body composition alongside weight and length in these children.
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