# Design and Modelling a Graduated Dispenser for Metabolic Diseases--Phenylketonuria
###### Abstract  
In metabolic diseases such as phenylketonuria (a rare disease), a very important way to keep the patient healthy is the administration of amino acid substitutes. This dispenser was designed because in other places (except home) for patients, it is very difficult to take the substitute powder due to the custom weight, which depends on the body weight. We designed and made on a 3D printer a graduated dosing device (12 g) which can be used very easily and has all the elements to be transported. In this way, the necessary dose of amino acid substitutes can be administered to patients with phenylketonuria, including infants aged 6 months-1 year, at the kindergarten or any other places with the absence of a food scale. This dispenser is very easy to carry and very useful to patients. graduated dispenser; design; modelling; 3D printing; metabolic disorder +
Footnote †: journal: Medical Imaging  
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Footnote 1: email: _Applied_  
Footnote †: journal: Medical Imaging  
To maintain the value within the safe range (120-480 umol/L or 2-6 mg/dL), it is necessary to observe the diet, the consumption of low medical foods with reduced phenylalanine content and the administration of the amino acid formula. Dosage of the amino acid formula does not depend on individual tolerance, but on the protein requirements of the PKU subject. To ensure the absorption of these amino acids from the formula, it is recommended that the protein requirement be increased by 40% compared to the recommendations for healthy people. The amino acid formula has been fortified with tyrosine, but it does not always cover the requirements for this amino acid, especially in adolescents and adults. Because the diet is restrictive, vitamins, minerals and carbohydrates are also found in these amino acid formulas [3]. In addition to monitoring the level of plasma phenylalanine, other nutritional indices must be evaluated annually, such as: plasma amino acids, plasma homocysteine or methylmalonic acid (indicators of vitamin B12 deficiency), hemoglobin and ferritin. The dosing of vitamins and minerals is also recommended, the most important being Ca, Zn, Se and the hormonal blood dosage. Growth parameters are also monitored, following the child's evolution, and neurological and neuropsychiatric tests are recommended if there are suspicions of neurological damage [4; 5]. Low protein foods with reduced phenylalanine content ensure an intake of 85% of the protein requirement, the difference of 15% being provided by natural proteins (fruits and vegetables). These medical foods are indispensable for PKU patients because they prevent protein deficiency, ensure energy requirements, metabolic control, and normal growth, and prevent zinc, iron, carnitine, selenium and vitamin B12 deficiency [6; 7]. Low protein foods are: flour, bread, pasta, cereals, pizza, rice, egg substitutes, meat substitutes, puree substitutes, and mixes for pastries, pancakes, muffins and other assortments. The worst neurological manifestations of this metabolic disease are prevented by early diagnosis, establishing and following the specific therapeutic diet. Even if there is adequate control of plasma phenylalanine, some behavioral, physical and neuropsychological problems may occur. Recent studies have shown that working memory alterations occur in PKU with a neonatal diagnosis since it has been associated with low adherence to treatment. The care of people with PKU requires a multidisciplinary effort (specialist doctor, dietitian, psychologist) and support is needed throughout life to maintain a good result, which consists in a normal development. Even if phenylalanine levels are within the safe range, changes in body composition may occur. Several studies in the field have shown that the studied patients with phenylketonuria show an increase in the percentage of energy due to carbohydrates compared to the percentage of energy from fats and proteins.