Galactosemia compromises bone health
MedWire News: People with galactosemia, especially women, exhibit marked bone loss and an increased risk for fracture, despite adhering to a galactose-restricted diet, a study by Dutch and US researchers indicates.
The etiology of the compromised bone status in these patients is unclear, and the researchers say they hope further work will identify targets for therapeutic intervention.
Galactosemia is an autosomal recessive disorder resulting in a deficiency of the galactose-1-phosphate uridyltransferase enzyme. This results in increased production of the metabolites galactitol and galactonate, both of which may have adverse effects on the ovaries and bone, among other tissues.
In this study, Catherine Gordon (Children's Hospital Boston, Massachusetts, USA) and team assessed skeletal health in 33 adults with classic galactosemia. The patients' mean age was 32.0 years, 16 were women, and the majority were of normal weight.
In both men and women, the average bone mineral density (BMD) Z-score fell below zero at both the hip and lumbar spine, indicating values significantly below those in a healthy age-, gender-, and ethnicity-matched population.
Interestingly, BMD was reduced to a greater extent in galactosemic women than in men with the disease. At the spine, 33% of women had a Z-score below -2.0 compared with 18% of men, while at the hip, 27% of women had a Z-score below -2.0 compared with just 6% of men.
The prevalence of fractures also varied by gender, with 63% of women reporting at least one lifetime fracture compared with 31% of men.
Multivariate analyses revealed that serum calcium level was consistently associated with BMD, such that each 1-mg/dL increment in serum calcium increased BMD by 0.16-0.18 g/cm2 at the lumbar spine and 0.14-0.16 g/cm2 at the hip.
In women only, osteocalcin levels demonstrated an inverse association with BMD, independent of the calcium effect, while the gonadotropins also showed significant inverse associations with BMD at the spine.
Writing in Osteoporosis International, Gordon et al conclude: "Our data suggest that low bone density is a frequent finding in adult patients with classic galactosemia, confirming results from previous studies and highlighting the point that its etiology is multifactorial.
"Ideally, interventions would start during childhood to promote optimal bone accrual and thereby improve lifetime bone health for this high-risk group."
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By Joanna Lyford