Management
Guidelines
Portal
PKU Nutrition Management Guidelines
First Edition
March 2015, v.1.12
Updated: August 2016
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Nutrition Recommendations
Question
6. For women with PKU, what nutritional therapies are associated with positive outcomes during pregnancy planning, pregnancy, and the post-partum period (including lactation)?
Conclusion Statement
Derived from evidence and consensus based clinical practice

High maternal blood PHE during pregnancy results in microcephaly, low birth weight, congenital heart disease, and intellectual disability in offspring of women with PKU. There is a wealth of evidence to show that this Maternal PKU syndrome (MPKUS) can be prevented if maternal blood PHE is controlled within a treatment range of 120-360 µmol/L before and during pregnancy. However very few studies contain robust dietary intake data. The primary source of nutrient intake data is the Maternal PKU Collaborative Study (MPKUCS), which indicated that protein, energy, fat, and vitamin B12 intakes all impacted blood PHE and/or birth outcomes. The diet for women with PKU who are pregnant must provide adequate protein, energy, fat, vitamins, and minerals to support normal fetal growth and development. This necessitates the use of low or PHE-free medical foods, and often modified low protein foods. The diet is very restrictive and unpalatable and adherence is often suboptimal, especially in women who have severe forms of PKU, less education, and lower IQ and socioeconomic status. However, with close monitoring of blood PHE and biochemical markers of protein, vitamin, and mineral status, normal birth outcomes are possible. Women with PKU are encouraged to maintain dietary therapy after pregnancy and to breastfeed their infants. Pyshosocial support during pregnancy is recommended. Sapropterin use in pregnancy has been limited and does not appear to be teratogenic, and is most likely to be of benefit to women with less severe forms of PKU. Large neutral amino acid therapy alone is not recommended during pregnancy.

Recommendation 6.1

Maintain blood PHE between 120 and 360 μmol/L before, during, and after pregnancy.

 
Strength of Recommendation:
Insufficient EvidenceConsensusWeakFairStrong
Clinical Action:
ConditionalImperative
Recommendation 6.2

Monitor weight gain, dietary intake, and biochemical parameters to ensure nutrient adequacy and metabolic control during pregnancy.

Strength of Recommendation:
Insufficient EvidenceConsensusWeakFairStrong
Clinical Action:
ConditionalImperative
Recommendation 6.3

Prescribe a diet that meets nutritional needs of pregnancy and promotes adequate weight gain.

Strength of Recommendation:
Insufficient EvidenceConsensusWeakFairStrong
Clinical Action:
ConditionalImperative
Recommendation 6.4

Avoid LNAA monotherapy during pregnancy.

Strength of Recommendation:
Insufficient EvidenceConsensusWeakFairStrong
Clinical Action:
ConditionalImperative
Recommendation 6.5

Use of sapropterin should be evaluated during pregnancy on a case-by-case basis, and may be appropriate especially in women with moderate or mild forms of PKU who are not able to maintain blood PHE in the recommended treatment range for pregnancy.

Strength of Recommendation:
Insufficient EvidenceConsensusWeakFairStrong
Clinical Action:
ConditionalImperative
Recommendation 6.6

Facilitate access to psychosocial support as necessary to maintain dietary therapy in pregnancy.

Strength of Recommendation:
Insufficient EvidenceConsensusWeakFairStrong
Clinical Action:
ConditionalImperative
Recommendation 6.7

Encourage women with PKU to maintain dietary therapy after pregnancy and to breast-feed their infants.

Strength of Recommendation:
Insufficient EvidenceConsensusWeakFairStrong
Clinical Action:
ConditionalImperative
Recommendation 6.8

Modify PKU therapy and collaborate with other care-givers to support nutritional and metabolic needs of women with multiple pregnancies, gestational diabetes, and other special circumstances.

Strength of Recommendation:
Insufficient EvidenceConsensusWeakFairStrong
Clinical Action:
ConditionalImperative
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