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2nd Dietitians’ Workshop

2nd Dietitians’ Workshop
  • Endocrinology and metabolism
  • Phenylketonuria (PKU)

Resource type


2nd dietitians workshop

Dietitians, nutritionists and physicians from across the world met in Rome (Italy) on March 22nd 2012 to discuss the latest research and developments in the dietary management of PKU. Final programme and abstracts of the workshop.

A packed agenda for the day provided delegates with the opportunity to hear presentations detailing the latest research in PKU management. Delegates had the opportunity to discuss issues raised by the main presentations, compare and contrast local practices and share best practice by participating in roundtable discussions and workshop sessions. Themes explored included:

  • micronutrient status in PKU
  • the assessment of nutritional status of PKU patients
  • issues arising from combining diet with sapropterin (tetrahydrobiopterin BH4) treatment
  • working effectively with, educating and motivating patients
  • the management of maternal PKU
  • considerations of quality of life for patients on strictly controlled diets.


Micronutrient issues in PKU

The workshop opened with presentations from Prof François Feillet1 and Prof Anita MacDonald2 focusing on the challenges of ensuring patients on PKU diets have correct levels of essential micronutrients. Both speakers expressed concerns that lack of monitoring of the nutritional status of PKU patients – principally due to considerations of practicality and cost – could be exposing patients to risk of poor health in the long term. Prof MacDonald highlighted the difficulties of assessing vitamin and mineral status such as blood sample quality, sample storage, inter-laboratory variation and lack of age specific reference ranges. Even if these sources of variation could be minimised, results could still be affected by diurnal variation, fasting status, acute infections and inflammatory stress.

Prof Feillet reminded the audience that while vitamins are present in high levels in many supplements to counter deficiency, they are not necessarily in a form that is readily bioavailable. With reference to key vitamins such as B12, linked to neurological symptoms in PKU patients, Prof Feillet stressed the importance of monitoring vitamin levels and supplementation when necessary.

Prof MacDonald discussed the current research into mineral levels in PKU patients, pointing out that ‘we provide copious quantities of nutrients within our special protein substitutes, but it is the quality of that nutrient source that counts.’ Prof MacDonald concentrated on selenium, iron and zinc, reviewing the importance of these minerals to metabolism and discussing the results of studies showing reduced levels of selenium and zinc in patients following a restricted diet.

In the discussion that followed, Dr Júlio César Rocha3 stressed the importance of testing for vitamin D3 levels, which can result in reduced bone mineral density over time.

Watch Prof Anita MacDonald’s lecture.


Introducing sapropterin

A series of case studies were presented at the meeting. The presentations were followed by a panel discussion.


Dosage of sapropterin in overweight patients, Dr Katharina Dokoupil4

2nd dietitians workshop 1

Dr Dokoupil discussed how obese patients present two problems for the clinician:

  • the correct dose needs to be determined – this can take time
  • the cost of maintaining an effective dose can outweigh the benefits of treatment.

Dr Dokoupil detailed the case of an obese patient who was initially given a dose of 4.7 mg/kg but required an eventual dose of 7 mg/kg to give a 50% reduction in blood Phe levels.


Managing illness with diet and sapropterin, Dr Hulya Gokmen-Ozel5

pku newsletter 01

Increased blood Phe levels in patients with infections and inflammation can create a dilemma for the physician said Dr Gokmen-Ozel. Although on one hand it is important to lower blood Phe levels, introducing too restricted a diet can reduce the patient’s ability to cope with infection. With reference to two cases, Dr Gokmen-Ozel recommended that sapropterin dose should be increased along with a reduction in animal protein and the provision of additional protein supplements.


Managing pregnancy with sapropterin, Friedrich K Trefz6

2nd dietitians workshop 06

Prof Trefz reported success in treating maternal mild PKU in a BH4-responsive pregnant woman who was intolerant of a Phe-restricted diet and had poor metabolic control. Adequate control was achieved with sapropterin and a low Phe diet. There were no health problems with the fetus. The mother experienced no side effects either during gestation or after delivery. There were no health problems with the baby.


Managing a second diagnosis with sapropterin, Ms. Kirsten Ahring7

2nd dietitians workshop 07

Mrs Ahring described how PKU with insulin-dependent diabetes mellitus (type 1 diabetes) presented particular problems for diet with reference to the case of a girl with mild PKU (BH4-responsive) who was diagnosed with type 1 Diabetes aged 3  years. Because the patient had mild PKU she could have been expected, were it not for the diabetes, to achieve good control of blood Phe with a free diet plus 5 mg BH4/kg of sapropterin. However, the required diets to give best control of PKU and diabetes conflict. It was necessary to provide higher doses of BH4 (up to 20 mg/kg) in order to give adequate control of both blood sugar and BH4. Observations that there was a stabilisation and lowering of blood sugar while taking the highest dose of BH4 prompted further investigation into whether BH4 was affecting blood-sugar level and the consumption of insulin. However, closer attention to diet brought better control of the diabetes and the final conclusion was that the BH4 had not been responsible for the observed effects.


Quality in the balance

pku newsletter 02

For PKU patients, happiness comes at a price, said Prof Anita MacDonald2 in her closing presentation to the workshop. Supporting patients, particularly adolescents, to make decisions about their diet must take their feelings about quality of life into account.

Adherence to a strict PKU diet is not easy and can be especially hard for adolescents. Maintaining blood Phe levels in the advised ranges puts huge pressure on patients and their families. For this reason, successfully treated patients often report a reduction in their health-related quality of life (HRQoL). Because HRQoL is a subjective measure of an individual’s satisfaction with parts of their life that affect their health, or are affected by it, the happiest adolescents tend to be those with the highest blood Phe levels and the least inconvenience from a restricted diet. These tests do not, however, properly take account of the negative effects of having PKU with poor dietary control.

2nd dietitians workshop 09

Relaxing dietary control may well improve the quality of a patient’s life, but at what cost? In children, relaxing control has a detrimental effect on the cognitive ability of the patient and should not be considered. In adults, ceasing dietary control does not cause a major decrease in IQ, however, high blood Phe is still associated with deficits in executive function (neuropsychological performance) and poor mood.

Therefore, dietary freedom and the associated lack of control of blood Phe does come at a price. Patients need to be educated that the potential advantages of going off diet have to be balanced against the negative effect on mood and executive function (loss of attention, etc). For many, a Phe-restricted ‘Diet for Life’ will still be the best option, Prof MacDonald concluded.



Dietitians’ Workshop Oral Presentation Highlights

Sapropterin effective at managing Phe levels in toddlers, Ms. Nicole Pallone8

Mrs Pallone discussed the case of patient RP, her daughter Rosie. RP is currently participating in a clinical study into the efficacy and safety of sapropterin in treating infants under 4 years (PKU 015 study). Despite close adherence to diet, RP had blood Phe levels that were occasionally above the recommended range (120–360 µmol/l). With sapropterin, RP’s blood Phe is consistently in the range 120–240 µmol/l while at the same time her Phe tolerance has doubled.


TXT 4 PKU, Ms. Sarah Boocock9

2nd dietitians workshop 11

In an era of ‘Individualised Medicine’ are clinicians taking advantage of the opportunities offered by technology to individualise their patient communications? Reminding patients to send in their monthly blood samples by sending a text message to their mobile phone is a valuable tool to aid compliance according to Miss Boocock. In an oral presentation, Miss Boocock presented the results of a year-long study involving 25 adult patients (aged 16+ years). Sending the patients monthly text message reminders when their samples were due increased the total number of blood spots returned by 65% (p=0.03). Additionally, 44% of patients increased the amount of blood spots sent in by 2 or more. The more adherent patients in the group benefited most from the reminders and were the most improved. The messages did little to improve adherence in the unmotivated patients.


Low plasma zinc and selenium widespread, Ms. Sarah Boocock9

Miss Boocock provided further information from recent work in Birmingham (UK) revealing, in an oral presentation, results suggesting that low plasma zinc and selenium concentrations are common in patients, whether or not they have adequate metabolic control of blood Phe through use of dietary supplements.


Education about PKU must go beyond the family, Dr Natalia Usurelu10

Dr Usurelu is both a physician and a parent of a PKU child. Her son was also her first PKU patient. Dr Usurelu reminded the delegates that a diagnosis of PKU means significant changes in the lifestyle not only of patients and their parents but also of their relatives, friends, teachers, caregivers, etc. Dr Usurelu discussed how education about PKU must not be directed only at patients and their families, but to society as a whole. This is vital if PKU patients and their families are to be properly supported by the institutions with which they have to deal on a day-to-day basis, such as schools.


Dietitians’ Workshop Session Highlights

A range of workshops enabled delegates to discuss local practices and share best practice.

Prof Laurie Bernstein11, leading the workshop on the education and motivation of patients, reviewed a range of tools. Key points in the discussion included:

  • psychological support is a valuable tool that can help counteract children’s embarrassment and frustration.
  • improving the way children and young people feel about their PKU can, in turn, improve family cohesion and diet adherence.
  • age-appropriate educational programmes and group activities are valuable as they build the ‘people skills’ of children and young people and increase the level of responsibility they take for their PKU.

The management of maternal PKU (MPKU) was discussed in the workshop led by Mrs Eleanor Weetch12 and Ms Kristina Motzfeldt13. Key points in the discussion included:

  • the best time to start controlling diet to benefit the baby is before it is conceived
  • risks to the developing child can be minimised by ensuring the mother keeps her weight and blood Phe levels under control (100–300 µmol/l) through an adequate diet that includes folic acid and essential fatty acids (200 mg DHA/day) which are not part of the normal PKU diet. Care needs to be taken with fish oil because of its vitamin A content
  • regular nutritional and biochemical assessment is essential throughout pregnancy
  • it is vital to provide information to both parents to increase adherence to diet.
  • breastfeeding is encouraged.

Delegates further discussed the assessment of nutritional status in a workshop led by Dr Júlio César Rocha14 and Dr Hulya Gokmen-Ozel15. The restricted diet of PKU children can lead to deficiencies of vitamins, minerals and omega 3 fatty acids. This leads to growth retardation. Obesity is a risk due to low physical activity coupled with excessive caloric intake. Only a supplemented and balanced diet can minimise these problems.

The ‘introducing sapropterin with diet’ workshop was led by Dr Margreet van Rijn16 and Dr Amaya Bélanger-Quintana17 who reviewed a number of case studies and led discussion on the best methods for introducing sapropterin with diet in mild PKU BH4-responsive patients. In these patients, sapropterin allows patients to reduce the level of protein restriction but they still require some amino acid supplementation. It is important to monitor the patient and adjust dosing according to metabolic control, age-targeted guidelines for blood Phe levels and under special circumstances (e.g. during infection or inflammation).


1  Prof François Feillet (Centre de Réferénce des Maladies Héréditaires du Métabolisme, Hôpital d’Enfants, CHU Brabois Vandoeuvre les Nancy, France)

2  Prof Anita MacDonald (Dietetic Department, The Children’s Hospital, Birmingham, UK)

3  Dr Júlio César Rocha (Centro de Genética Médica, Jacinto de Magalhães, Instituto Nacional de Saúde, Porto, Portugal)

4  Ms Katharina Dokoupil (Department of Metabolism and Nutrition, Dr von Hauner Children's Hospital, University of Munich, Munich, Germany)

5  Dr Hulya Gokmen-Ozel (Faculty of Health Sciences, Department of Nutrition and Dietetics, Hacettepe University, Ankara, Turkey)

6 Prof Friedrich K Trefz (Medical Centre Gammertingen, Kreiskliniken Reutlingen GmbH, Gammertingen, Germany)

7 Mrs Kirsten Ahring (PKU Department, The Kennedy Center, Bagsværd, Denmark)

8 Mrs Nicole Pallone (vice president of Canadian PKU and Allied Disorders, Ottawa, Canada)

9  Miss Sarah Boocock (Nutrition and Dietetics Department, Queen Elizabeth Hospital, Birmingham, UK)

10 Dr Natalia Usurelu (The National Center of Reproductive Health and Medical Genetics, Chisinau, Republic of Moldova)

11 Prof Laurie E Bernstein (Department of Pediatrics, University of Colorado School of Medicine, Denver, Colorado, USA)

12 Mrs Eleanor Weetch (Nutrition and Dietetics, National Society for Phenylketonuria, UK & Adult Metabolic Dietitian, Northern General Hospital, Sheffield, UK)

13 Ms Kristina Motzfeldt (Department of Pediatrics, Women and Children’s Division, Section for Specialized Medicine and Unit for Newborn Screening, Oslo University Hospital, Norway)

14 Dr Júlio César Rocha (Centro de Genética Médica, Jacinto de Magalhães, Instituto Nacional de Saúde, Porto, Portugal)

15 Dr Hulya Gokmen-Ozel (Faculty of Health Sciences, Department of Nutrition and Dietetics, Hacettepe University, Ankara, Turkey)

16 Dr Margreet van Rijn (Section of Metabolic Diseases, Beatrix Children’s Hospital, University Medical Center Groningen, Netherlands)

17 Dr Amaya Bélanger-Quintana (Unidad de Enfermedades Metabólicas, Servicio de Pediatría, Hospital Ramón y Cajal, Madrid, Spain)

Terms of use

This is a copyrighted resource for the sole purpose of education. Resource may be used for classroom training only and must remain as is, including the branding and EXCEMED logo. It is backed by a publishing license, signed by the author.

Rome, Italy
Mar 22, 2012
Target audience
Dietitians, nutritionists, health professional
by Excemed
Endocrinology and metabolism