Bone Abstracts

Objectives: To evaluate bone health and its possible correlations to body composition parameters in young patients with galactose metabolic disorders, aiming to suggest appropriate lifestyle interventions.

Methods: We studied 22 patients, aged 5–16 years with galactose metabolic disorders, detected by neonatal screening. Fourteen suffered from classic galactosemia and eight from other galactose metabolic disorders (i.e. epimerase or galactokinase deficiency or homozygosity in Duarte type 2). All subjects had normal growth and were under strict dietary control, using a non-soya product, which is a casein-based, lactose-free feed, enriched with vitamins and minerals. They were followed-up closely (every 6 months). Bone mineral density and body composition were assessed with dual X-ray absorptiometry and the results were compared to the reference population of the pediatric software of the apparatus. We evaluated areal bone mineral density of the lumbar spine and total body, lean tissue mass, body fat percentage, fat mass index and bone strength (bone mineral content/lean tissue mass ratio).

Results: In both groups, bone strength and median bone mineral density Z-scores were within normal limits at both sites. However, classic galactosemia patients appeared sarcopenic (median lean tissue mass Z-score =−1.93, P<0.05), whereas subjects with other enzymatic defects had low-normal muscle mass. Also, nearly half of all patients were either overweight or obese. In classic galactosemia, spine and total body bone mineral density were strongly correlated to muscle mass (r=0.81 and r=0.9 respectively, P<0.05). In patients with other galactose metabolic disorders, bone mineral density of total body was positively correlated to BMI (r=0.78, P<0.05). Finally, an almost linear relationship was found between body fat percentage and fat mass index.

Conclusion: Adequate dietary control and close follow-up favour our patients’ bone health. However, it appears that there is an imbalance between muscle and fat mass, especially in patients with classic galactosemia. Given the observed strong correlation between bone and muscle mass, counseling on exercise is needed, in order to prevent sarcopenia, combat fatness and preserve bone quality.