[Concentration of osteoprotegerin, bone formation and resorption markers in patients with phenylketonuria].
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.


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.
Department of Newborn Screening, Institute of Mother and Child, Warsaw, Poland. bioklin@imid.med.pl
Jadwiga
J
Ambroszkiewicz
Joanna
J
Gajewska
Magdalena
M
Chełchowska
Mariusz
M
Ołtarzewski
Teresa
T
Laskowska-Klita
Maria
M
Nowacka
Andrzej
A
Milanowski
D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D001851:Bone Diseases, Metabolic / Q000209:etiology; D001862:Bone Resorption / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D024042:Collagen Type I / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D015675:Osteocalcin / Q000097:blood; D010012:Osteogenesis; D010024:Osteoporosis / Q000209:etiology; D053244:Osteoprotegerin / Q000097:blood*; D010455:Peptides / Q000097:blood; D010661:Phenylketonurias / Q000150:complications / Q000378:metabolism*
D015415:Biomarkers; D024042:Collagen Type I; D053244:Osteoprotegerin; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D015675:Osteocalcin
Stezenie osteoprotegeryny oraz markerów kościotworzenia i resorpcji kości u chorych na fenyloketonurie.