UNLABELLED: Non-invasive biochemical markers which show global skeletal activity have lately been developed and validated for the assessment of bone formation and bone resorption processes. Among them, osteocalcin (OC) and collagen type I cross-linked C-telopeptide (CTX) are considered to be clinically useful. Recently the novel cytokine osteoprotegerin (OPG), belonging to the tumour necrosis factor receptor family, has been established as an endogenous inhibitor of osteoclastogenesis and resorption processes. Some authors have observed decreased bone mineral density and osteopenia in patients suffering from phenylketonuria (PKU). The aim of the study was to assess osteoprotegerin and some bone formation and resorption markers concentrations in phenylketonuric patients. MATERIAL AND METHODS: We measured OPG, OC and CTX in 112 patients with PKU treated at the Department of Pediatrics of the Institute of Mother and Child in Warsaw. Healthy subjects in the same age range sent to our laboratory for routine analytical control were the reference group. Serum bone metabolism markers were determined by an immunoenzymatic assays. RESULTS: Mean serum level of OPG was significantly lower in PKU patients than in controls: in prepubertal and postpubertal subjects by about 15% and in adolescents by 35% respectively. Serum OC and CTX in prepubertal children with PKU compared to the control group was lower by 20-25%. In adolescents both markers were slightly lower (by about 10%) and in postpubertal subjects OC was lower by 25% and CTX by 15% compared to the age-matched controls. CONCLUSIONS: Our results indicate that in phenylketonuric patients an imbalance between bone formation and degradation processes occurred and they are at risk for osteopenia and osteoporosis in later life.
UNLABELLED: Non-invasive biochemical markers which show global skeletal activity have lately been developed and validated for the assessment of bone formation and bone resorption processes. Among them, osteocalcin (OC) and collagen type I cross-linked C-telopeptide (CTX) are considered to be clinically useful. Recently the novel cytokine osteoprotegerin (OPG), belonging to the tumour necrosis factor receptor family, has been established as an endogenous inhibitor of osteoclastogenesis and resorption processes. Some authors have observed decreased bone mineral density and osteopenia in patients suffering from phenylketonuria (PKU). The aim of the study was to assess osteoprotegerin and some bone formation and resorption markers concentrations in phenylketonuricpatients. MATERIAL AND METHODS: We measured OPG, OC and CTX in 112 patients with PKU treated at the Department of Pediatrics of the Institute of Mother and Child in Warsaw. Healthy subjects in the same age range sent to our laboratory for routine analytical control were the reference group. Serum bone metabolism markers were determined by an immunoenzymatic assays. RESULTS: Mean serum level of OPG was significantly lower in PKUpatients than in controls: in prepubertal and postpubertal subjects by about 15% and in adolescents by 35% respectively. Serum OC and CTX in prepubertal children with PKU compared to the control group was lower by 20-25%. In adolescents both markers were slightly lower (by about 10%) and in postpubertal subjects OC was lower by 25% and CTX by 15% compared to the age-matched controls. CONCLUSIONS: Our results indicate that in phenylketonuricpatients an imbalance between bone formation and degradation processes occurred and they are at risk for osteopenia and osteoporosis in later life.