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PKU in adolescents and adults

PKU in adolescents and adults. Andrew Morris Royal Manchester Children’s Hospital. Manchester PKU patients. 60. 50. children (n=115). adults (n=211). 40. Number. 30. 20. 10. 0. 0-5. 6-. 11-. 16-. 21-. 26-. 31-. 36-. 41-. 46-. 51-. 56-. 61-. 10. 15. 20. 25. 30. 35.

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PKU in adolescents and adults

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  1. PKU in adolescents and adults Andrew Morris Royal Manchester Children’s Hospital

  2. Manchester PKU patients 60 50 children (n=115) adults (n=211) 40 Number 30 20 10 0 0-5 6- 11- 16- 21- 26- 31- 36- 41- 46- 51- 56- 61- 10 15 20 25 30 35 40 45 50 55 60 65 Age (yrs)

  3. High phenylalanine levels are harmful to the developing brain • Phenylalanine must be strictly controlled in infancy, childhood and in pregnancy • Stopping the PKU diet after childhood does not have a major effect on IQ

  4. Adult PKU management Prevention of • Damage to children of PKU mothers • Nutritional problems • Late neurological problems (?)

  5. PKU & Pregnancy • Low risk of child having PKU (1:100) • High risk of child being damaged by mother’s high phenylalanine levels

  6. Untreated Maternal PKU Adverse effects on infant • Mental retardation (92%) • Abnormally small head (73%) • Low birth weight (40%) • Congenital heart disease (12%) • Abnormal facial appearance Lenke & Levy, 1980

  7. Congenital heart disease International study Diet pre- 0/23 conception (0%) Diet after 10 34/235 weeks gestation (14%)

  8. Maternal PKU: when to start strict diet International study recommended levels down by 10 weeks gestation BUT - takes time to get levels down - vomiting in early pregnancy • Pre-conception • If unplanned as soon as possible • If very late consider termination

  9. Maternal PKU: Problems • Diet is difficult • Cost • Waiting to conceive whilst on diet • refer to reproductive medicine after 6 months • Vomiting • Learning difficulties in some patients • Poor support from some doctors

  10. Adult PKU management Prevention of • Damage to children of PKU mothers • Nutritional problems • Late neurological problems (?)

  11. Nutrition in PKU Adults On PKU diet • Supplements often taken erratically Off PKU diet • Diet often low in red meat & dairy foods • low in vitamin B12 iron calcium

  12. Vitamin B12 levels in PKUs on & off diet Diet : strict relaxed normal 600 n=30 n=29 n=25 Normal Range 500 B12 level in blood (ng/l) 400 300 200 100 0 Pts with low B12 1 3 6

  13. Adult PKU management Prevention of • Damage to children of PKU mothers • Nutritional problems • Late neurological problems (?)

  14. Adults with PKU High phenylalanine levels cause • Minor symptoms in some patients • Poor concentration • Lethargy • Irritability

  15. Adults with PKU High phenylalanine levels cause • Minor symptoms in some patients • Abnormalities on brain scans • White matter • Reversible if phenylalanine lowered

  16. White matter changes Probably due to increased water content Normal

  17. Adults with PKU High phenylalanine levels cause • Minor symptoms in some patients • Abnormalities on brain scans • Neurological problems (very rare)

  18. Neurological problems after stopping PKU diet Stiffness Poor balance Epilepsy Poor short term memory • Very rare • Most patients had poor early control • Often reversible on restarting diet

  19. Adults with PKU High phenylalanine levels cause • Minor symptoms in some patients • Abnormalities on brain scans • Neurological problems (very rare) • Unknown effects in very long term • No early treated patients have yet reached 50 yrs

  20. Adolescents with PKU • Poor dietary control may lead to disappointing exam results • No good studies • families with good dietary compliance also likely to encourage studying • randomised controlled trials not possible

  21. Adolescents: recommendations • Dietary treatment • Phenylalanine levels 120-700 mcmol/l Not worth pursuing if leads to • Family breakdown • Serious nutritional problems

  22. What are we achieving? 90 % phe samples outside target range 80 70 60 50 40 30 20 10 0 Age 4 6 8 0 2 10 12 14 18 20 16 Target range 120-360 120-480 120-700

  23. Management of adults with PKU PKU clinics provide information Patients choose whether to stay on diet Everyone needs regular review to • Support patients on diet • Prevent nutritional problems • Monitor for neurological problems • Ensure strict diet during pregnancy

  24. Treatment of PKU • Phenylalanine restricted diet • Amino acid supplements • Low protein products • Vitamins & Minerals • Monitoring of phenylalanine levels

  25. Adult PKU: neurological abnormalities Brisk reflexes Tremor • Asymptomatic • Common • On or off diet

  26. Scan abnormalities and phenylalanine level Phe 2000 1500 1000 500 0 5 10 15 20 25 Severity of abnormality on scan

  27. Phenylketonuria PA Hydroxylase Phenylalanine Tyrosine BH4 BH2 DHPR Phenylketones

  28. UK (1993) pre-school: 120-360 µmol/l (2-6 mg/dl) school age: 120-480 µmol/l (2-8 mg/dl) adolescence: 120-700 µmol/l (2-11.7 mg/dl) German (1999) <10 y 40-240 µmol/l (0.7-4 mg/dl) 10-15 y 40-900 µmo/l(0.7-15 mg/dl) >15 y 40-1200µmol/l (0.7-20 mg/dl) Published guidelines

  29. Management of PKU adults in UK UCH is the largest centre with 270 adult patients

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