PHENYLKETONURIA (PKU) Case Study Presentation Cassidy Baerg NUTR 426

OBJECTIVES 1. To recognize signs and symptoms associated with a PKU diagnosis. 2. To gain an elementary understanding of what causes this disease state. 3. To outline a basic intervention plan for a patient with PKU.

WHAT IS PKU?  PKU is an inherited amino acid disorder in which the essential amino acid phenylalanine is unable to be converted into tyrosine due to a an absence of Phenylalanine reductase or dihydropteridine reductase.

TWO TYPES 1. Classic PKU 2. Non-variant PKU

EPIDEMIOLOGY  According to the National Institute of Health PKU occurs in about 1 in 10,000-15,000 newborns in the United States.  PKU occurs more often in Caucasian and Native American populations than in African American or Hispanic populations.

DIAGNOSIS:  In the United States newborns are screened for PKU approximately 48 hrs after birth.  A Guthrie or heel prick test is used to test for PKU.  Classic PKU occurs when plasma phenylalanine levels exceed 20 mg/dL (1200 µmol/L) without intervention. 

PATIENT D.O.  Caucasian female.  Born at 38 weeks gestation.  Birth weight = 5 pounds 7 oz.  Length = 18 in.  Head Circumference 12.6 in.  Apgar: 5 and 6 at 1 min. and 5 min. respectively.  Guthrie test came back positive for PKU.  plasma phenylalanine concentration was 8.5 mg/ dL or 508 mol/ L (Normal = 0.5 mg/dL-1.7 mg/dL )  Second Guthrie test on day 6, 22.0 mg/ dL or 1321 mol phenylalanine/ L plasma.

ASSESSMENT  Small For Gestational Age (Preterm)  No Asymmetrical Growth Retardation  Below Normal Apgar  Difficult Birth  High Phe concentrations  Positive Guthrie Test For PKU

NUTRITION RX:  Started on PKU diet at 7 Days Old.  Estimated Needs (initial):  Phe = 70mg/kg = 2.82 kg (5 # 4 oz at 6 days old) = mg  Pro = 3.5 g/kg = 2.82 kg x 3.5 = 9.87 g  Energy = 120 kcals/kg =  Fluid = mL/kg = 148mLx 2.82 = mL

DIAGNOSIS: SAMPLE PES:  Excessive bioactive substances intake (too much Phe RT excessive intake of foods high in Phe amino acids AEB a Phe blood plasma concentration of 26.4 mg/dL at 6 days old.  Excessive bioactive substances intake (too much Phenylalanine) RT nutrition-related knowledge deficit AEB increased levels of Phe and a Guthrie test positive for PKU.

INTERVENTION  Control Phe blood plasma concentrations by getting the mother’s breast milk tested for Phe levels.  Augment diet with an infant formula low in Phe such as Periflex  Educate parents about PKU and a diet low in Phe amino acids.  Discuss possible nutrient deficiencies with a low Phe diet such as Kcals, iron, calcium, B12 and Vit D.  Emphasize the importance of regular visits with the RD.

MONITORING AND EVALUATION  Monitor lab values for Phe/Tyr.  Monitor albumin/prealbumin.  Do a 24 hr diet recall and typical diet recall in order to assess Ca, Vit D, and B12 status.  Evaluate the effectiveness of the nutrition education component

FOLLOW-UP  D.O. breastfeed for 11 mo.  Phe levels within acceptable range.  Family adjusting well to low Phe diet.  Food introduction similar to normal children.  At 13 mo. Phe increased…

IN CLASS ACTIVITY  Question?  Why did D.O.’s Phe suddenly increase?

ANSWERS: PER 100G EDIBLE PORTION LowHigh  Apple  Marshmallows  Sugar  Tomato  Carrot  Peaches  Grapefruit  Head Lettuce  White Rice  Egg White  Tofu  Beef  Seaweed  Peanuts  Dry active yeast  Gelatin  Yellow cheese  Aspartame  Salmon  Buttermilk Pumpkin seeds  Pork nine/confectioneries/low/

CONCLUSIONS:  PKU is a chronic disease that requires life-long treatment with a Phe controlled diet.  According to the Nelms text, a study comparing Phe concentrations to IQs demonstrated that for every 100umol/L increase in Phe above the target range IQ was decreased points.  Proper nutrition is vital for people with this disease.

REFERENCES  Nelms M, Sucher K, Lacey K, Roth SL. Nutrition Therapy and Pathophysiology 2/e. United States: Wadsworth Cengage Learning; 2011,  Phenylketonuria [Internet]: Federal Government Website; c2012. Available from:  Birth to 36 months: Head circumference for age and Weight for length percentiles [internet]: National Center for Health Statistics; c2001. Available from:  > Nutrients > Phenylalanine > Confectioneries Low in Phenylalanine: WholeFoodCatalog; c2011. Available from: