Risk factors for developing mineral bone disease in phenylketonuric patients.
There is a compromised bone mass in phenylketonuria patients compared with normal population, but the mechanisms responsible are still a matter of investigation. In addition, tetrahydrobiopterin therapy is a new option for a significant proportion of these patients and the prevalence of mineral bone disease (MBD) in these patients is unknown. We conducted a cross-sectional observational study including 43 phenylketonuric patients. Bone densitometry, nutritional assessment, physical activity questionnaire, biochemical parameters, and molecular study were performed in all patients. Patients were stratified by phenotype, age and type of treatment. The MBD prevalence in phenylketonuria was 14%. Osteopenic and osteoporotic (n=6 patients) had an average daily natural protein intake significantly lower than the remaining (n=37) patients with PKU (14.33 ± 8.95 g vs 21.25 ± 20.85 g). Besides, a lower body mass index was found. There were no statistical differences in physical activity level, calcium, phosphorus and fat intake, and in phenylalanine, vitamin D, paratohormone, docosahexaenoic and eicosapentaenoic acid blood levels. Mutational spectrum was found in up to 30 different PAH genotypes and no relationship was established among genotype and development of MBD. None of the twelve phenylketonuric patients treated with tetrahydrobiopterin (27.9%), for an average of 7.1 years, developed MBD. Natural protein intake and blood levels of eicosapentaenoic acid were significantly higher while calcium intake was lower in these patients. This study shows that the decrease in natural protein intake can play an important role in MBD development in phenylketonuric patients. Therapy with tetrahydrobiopterin allows a more relaxed protein diet, which is associated with better bone mass.
Unit of Diagnosis and Treatment of Congenital Metabolic Diseases, Department of Pediatrics, Hospital Clinico Universitario de Santiago, Travesía da Choupana s/n, 15706 Santiago de Compostela, A Coruña, Spain. amirvei@hotmail.com
Alicia
A
Mirás
M Dolores
MD
Bóveda
María R
MR
Leis
Antonio
A
Mera
Luís
L
Aldámiz-Echevarría
José R
JR
Fernández-Lorenzo
José M
JM
Fraga
María L
ML
Couce
D000293:Adolescent; D000328:Adult; D001708:Biopterins / Q000031:analogs & derivatives / Q000494:pharmacology / Q000627:therapeutic use; D015992:Body Mass Index; D018488:Bone Demineralization, Pathologic / Q000150:complications / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D015519:Bone Density / Q000187:drug effects; D001851:Bone Diseases, Metabolic / Q000150:complications / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D002118:Calcium / Q000378:metabolism; D002648:Child; D003430:Cross-Sectional Studies; D004044:Dietary Proteins / Q000008:administration & dosage*; D015118:Eicosapentaenoic Acid / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008903:Minerals / Q000008:administration & dosage*; D009043:Motor Activity; D009154:Mutation; D010024:Osteoporosis / Q000150:complications / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D010651:Phenylalanine Hydroxylase / Q000235:genetics / Q000378:metabolism; D010661:Phenylketonurias / Q000150:complications / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D012307:Risk Factors; D011795:Surveys and Questionnaires
D004044:Dietary Proteins; D008903:Minerals; D001708:Biopterins; D015118:Eicosapentaenoic Acid; D010651:Phenylalanine Hydroxylase; C003402:sapropterin; D002118:Calcium