Serum markers of bone turnover in children and adolescents with classic galactosemia

Abstract

Classic galactosemia is an inherited metabolic disease resulting from galactose-1-phosphate uridyltransferase (GALT) deficiency. Dietary lactose exclusion reverses many clinical manifestations of acute phase of the disease. Unfortunately most of the patients, despite dietary treatment, develop long-term complications among them disturbances of bone mineralization resulting in decrease of bone mineral density (BMD). The aim of our study was to assess bone formation and resorption processes with bone turnover markers in children and adolescents with galactosemia. We studied 62 galactosemic children (mean age+/-SD 5.9+/-2.7 years) and adolescents (mean age+/-SD 15.6+/-2,4 years). The clinical diagnosis had been confirmed by the absence of GALT activity in erythrocytes. All patients were diagnosed in the neonatal period and had good dietary control. Healthy children (n=70) were the reference group. Serum osteocalcin (OC), bone alkaline phosphatase (BALP), collagen type I crosslinked C-telopeptide (CTX-I), 25(OH)D metabolite of vitamin D were determined by ELISA assays. We observed similar mean values of bone formation markers in children with galactosemia as compared to the age-matched controls. The level of bone resorption marker CTX-I in these patients was lower by about 20% (p<0.001) than in healthy children. On the contrary we obtained slightly higher values of CTX-I in adolescents with galactosemia in comparison to the age-matched controls. In these patients the values of OC and BALP were significantly higher than in healthy adolescents (111.8+/-52.1 microg/L versus 82.3+/-43.0 microg/L, p<0.02; and 95.4+/-45.7 U/L versus 72.6+/-40.6 U/L, p<0.05 respectively). Our results suggest that bone turnover in galactosemic patients elevates from childhood to adolescence, whereas in healthy individuals there is a decline during aging. Further studies on adults with galactosemia are necessary to assess bone status in these patients.