Phenylketonuria a case study

Classical type of phenyleketonuria (PKU) is characterized by complete or near complete deficiency of phenylalanine hydroxylase. Classical PKU is associated with less than 2% activity of normal phenylalanine hydroxylase. The infants are normal at birth, if the disease is unrecognized and untreated, mental retardation may develop gradually and may not be evident for few months.

A 16 years old female child was detected to have a phenylketonuria classical type at the age of one year and seven months. A child was born of consanguineous marriage of Punjabi community and was referred for mild delay in her milestones. Child was preterm delivery born at 8 months with 2.1 kg of birth weight. Hyperbilirubinemia was noticed on fourth day of life. Child was only on breast feed for first four months of life. Light colored hair was noticed at the age of 4 months. Color of the hair was golden brown and urine with "musty odor". Her milestones at the time of first visit were as follows.

Head control 2 months
Trunk control sitting 7 months
Standing When made to stand - stands with support on her own at 18 months of age.
Sitting 1 year on her own
Walking Support with one hand - 1 year few steps now.
Fine motor Approach to a toy - 6 months.
Adaptive Release of an object - 15 months.
Pincer grasp - 15 months.
Social smile - 1 month
fear of stranger - 14 to 15 months.
Feeding - feeds her self -one year.

Bladder control - indicates occasionally.
Indicates water and food when she wants.
Language Speaks 4 words ,with meanings - 14 to 15 months.

On Examination :

Height - 85 CMS (50-75%)

Weight - 10 kg. (50%)

Head Circumference - 46.5 CMS.

Skin, Hair - Color of the skin - fair

Color of the hair - listic -golden

Iris color - light brown

Hyperpigmentation - Nil Others - Nil

After the diet advised, IQ assessment was done. The report for the IQ is as follows ;

Age 2 years and 6 months.
Sex female child.
Test used 1) Dr. Shukla's Intelligence Test.
2) Vineland Social Maturity Scale.(V.S.M.Scale)

Test results - Mental assessment - 2 years 8 months - IQ 107.

- Social assessment - 3 years and 8 months- IQ - 146.

Test Behavior -

She found to be active, demanding, curious, happy alert child. She was persistent in doing her task. Her grasping power was good.


1) Dr. Shukla's test : She passed all the items at 2 years level and failed at 5 years level. Her immediate memory for digits was up to 4 years level, while she was unable to say 14 words at the same year level. Her picture vocabulary, observation power, and Knowledge of every day things, in terms of use were good. She could identify body parts correctly. Her form perception was also good. Hand eye co-ordination was rather weak. She showed ability to master it with a little practice.

2) V.S.M. Scale : The levels development indifferent areas of social competency are as under :

  3.2. 85 3.4.84
Self help eating 5 Yr. 1 Yr. 6 months appx.
Self help dressing 3 Yr. 4 months below one year
Self help general 3 Yr. 8 Months 1 Yr. 5 Months.
Communication 2 Yrs. 6 Months. 11 months
Locomotion 5 Yrs. 3 months 1 Yr. 6 Months.
Occupation 5 Yrs 2 Yrs
Socialization 4 Yrs. 3 Months. 1 Yr. 6 Months.


While prescribing the diet the foodstuffs which are low in phenylalanine and high in calories should be selected. This diet should provide all nutrients in required quantities and should also provide satiety. Very low phenylalanine contained foods can be used in liberal amount. It is difficult to maintain serum phenylalanine levels in accepted range purely on natural diet. Majority of them contains 3 to 5% of protein as phenylalanine. Foods of animal origin, cereals, dry legumes nuts, potatoes, sweet potato, and fresh vegetables that are immature seeds such as sweet corn, cow peas, peas, and other fresh shelled beans contains 5% of protein as phenylalanine. Dark green leaves contains4 % protein as phenylalanine. Other fruits and vegetable contains 3% of protein as phenylalanine. When we dives the diet we come across many difficulties as most of the foodstuffs contains phenylalanine in larger or smaller quanity. Hence some times we have to take the help of the special chemically define formulas which are available in United States. In India it is not available hence we have to import it which is very costly. Breast milk supplies 65 kcals 1.1 gm of protein and 50 mg of phenylalanine and same amount of tyrosine. Where as buffalo's milk contains 117 kcals, 4.3 gm of protein, 186 mg of phenylalanine per 100 ml and cow's milk contains 67 Kcals 3.2 gm of protein and 157 mg of phenylalanine per 100 ml.

Patientís original diet was

Rice one wati

Wheat flour chapati once a day

Nestrum with banana two times a day.

Initially she had been given a diet of 435 mg of phenylalanine per day and later on was changed frequently as per her blood phenylalanine levels as shown in table.

Different plasma Phenylalanine levels

Test performed on Diet (mg) PA levels
6.2.84(newly)   40 mg%
10.2 84 diet advised 35 mg%
14.2.84 435 24 mg%
20.2.84 200 18 mg%
28.2.84 200 7 mg%
12.3.84 350 10.4 mg%
10.4.84 375 9 mg%
May 84 albumaid was started    
21.12.84 Addition of bread 14.6 mg%
Feb. 85 325 -350 12 -15 mg%
July 85 250 - 300 6 mg%
June 86 275 6 mg%

P K Aid Started (20 gm)  
Nov. 87 10 mg%

Now after these values her phenylalanine levels are between 4 to 8 mg%.

The menu of 435 mg of phenylalanine, 13 g of protein and 983 kcals includes

Cow's milk 90 ml
Rice 60 g
Potato 100 g
Banana 50 g
Rice flakes 30 g
Sugar and/or jaggary 50 g
Oil, ghee, butter etc.
25 g Vegetable 50 g.

Now she is taking full diet except few restrictions. Her latest blood phenylalanine level is 9 mg%.

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