A Third of Youngsters with XLH are Overweight or Obese, Study Finds
Approximately one third of children and young adults with X‐linked hypophosphatemia (XLH) are overweight or obese, a study has found.
Lack of family history of XLH and longer treatment with phosphorus supplements were identified as risk factors for excessive weight gain in these patients.
The study, “Prevalence of overweight and obesity in children with X-linked hypophosphatemia,” was published recently in the journal Endocrine Connections.
XLH is caused by a mutation in the PHEX gene that leads to the excessive production of a hormone called fibroblast growth factor 23 (FGF23). This hormone prevents kidneys from reabsorbing phosphate, leading to chronic hypophosphatemia (low blood levels of phosphate), a hallmark of XLH.
Studies have linked low phosphorus intake with the progression of weight gain and metabolic syndrome. Moreover, low blood phosphate levels have been tied to higher body mass index (BMI).
A research team from France and Italy assessed whether such a link is evident in young patients with XLH.
The study included data from 172 children and young adults with XLH (113 girls and 59 boys), who had been monitored for at least three years after being diagnosed with the disorder.
Study participants were divided into four age groups: 126 children were placed in group 1 (ages 5–7); 88 in group 2 (ages 7–10); 91 in group 3 (ages 10–15); and 49 adolescents and young adults in group 4 (ages 15–20).
Weight, height and BMI data were collected at birth, and during follow-up when participants reached an average age of 5 (group 1), 8 (group 2), 11 (group 3) and 16 (group 4).
Patients in each group were classified as overweight (BMI of 25–30 kg/m2) or obese (BMI higher than 30 kg/m2).
Results revealed that almost a third of the patients were overweight or obese in all four age groups (29.4% in group 1; 28.7% in group 2; 27.5% in group 3; and 36.7% in group 4).
Older girls showed a significant increase in the percentage with excess wight or obesity compared to those in the younger group. No such age-related association was seen in boys.
Researchers found that children and adolescents who had a family history of XLH had lower BMI values compared to those without such history.
They also discovered that longer treatment with phosphorus supplements was associated with higher BMI. Average BMI was 23.3 kg/m2 in those treated for less than five years, 23.8 kg/m2 in patients on treatment for 5–10 years, and 25.2 kg/m2 in participants taking phosphorus supplements for more than a decade.
The proportion of overweight/obese was higher in the group on phosphate supplements for more than 10 years (42.9%), compared to participants treated for less than five years.
Statistical analyses confirmed a link between treatment duration, lack of family history of XLH, and higher BMI values.
“The results of our study have an important impact for health-care providers. In clinical routine practice, careful evaluation and consistent monitoring of BMI is required for children affected by XLH. It may be of utmost importance for adulthood, given the risk for rheumatologic complications in adults with XLH,” the investigators wrote.
“Finally, the lack of XLH-family history and longer duration of phosphate supplementation could help to individuate those patients for whom a particular attention should be given in controlling the weight gain,” they added.
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