Comparison of Atherogenic Risk Factors and Efficacy of Nutritional Treatment Among Adult Phenylketonuria Patients

Selection and presentation of the problem and formulation of goals Phenylketonuria (PKU) oz. Hyperphenylalaninemia (HPA) is a rare congenital metabolic disease (PPB) due to a lack of phenylalanine hydroxylase (PH) activity, which metabolizes the amino acid phenylalanine (Phe) to tyrosine in the body. The cause is a disease change in the PAH gene that encodes the enzyme PH. A baby is born healthy, but elevated Phe levels without proper treatment cause central nervous system damage and permanent mental retardation in the first months after birth. The disease is the first PPB to be detected by medicine with neonatal screening tests and also successfully treated with dietary treatment that excludes foods with a higher Phe content from the diet. In Slovenia, the screening test was introduced in 1979 and with a calculated incidence of PKU 1/6769 in Slovenia (Šmon et al., 2015), there are approximately 150 patients with PKU in the Slovenian registry, of which more than half are over 18 years of age.

Nutritional treatment is an important part of PKU treatment and should be performed for life according to modern guidelines (Cazzorla et al., 2018).

Dietary treatment of PKU is one of the strictest diets, where almost all foods containing protein are excluded from the food, ie all diets of animal origin (meat, milk and all dairy products, eggs) as well as all cereals, legumes and nuts. Patients consume only limited amounts of fruits and vegetables and special products with a removed protein content. They compensate for the protein deficiency with special Phe-free protein substitutes. Adult patients with PKU often do not reach the recommended levels of Phe in the blood (Green et al., 2019), as the consequences of abandoning the diet in adulthood are not as obvious and disturbing. By abandoning the diet, however, they also abandon follow-up in a specialist PPB clinic, and according to studies, more than 70% of adult patients with PKU (study in America) are no longer managed in metabolic clinics (Berry et al., 2013).

Successful disease management often requires a lifelong diet that provides an appropriately limited daily intake of Phe for growth and body regeneration with a small portion of essential amino acids, vitamins, and natural food elements, and the remaining missing portion of these dietary sources is added in the form of protein-fortified protein. , which does not contain the amino acid Phe (MacLeod et al., 2009). Phe tolerance (mg Phe / kg body weight / day) is the amount of Phe that PKU patients can consume daily while maintaining recommended blood Phe levels. An individual assessment is required due to the very diverse level of Phe hydroxylase enzyme activity still present (MacLeod et al., 2009). The measure of dietary success is an adequate value of serum Phe and the latest European recommendations in adulthood are between 120 - 600 μmol / L (van Spronsen et al., 2017; van Wegberg et al., 2017).

Research in recent years has shown significantly higher morbidity and health risk in adult patients with PKU. Part of the health problems are also more present in patients who continue dietary treatment, and there are even more problems in untreated patients (Burton et al., 2018).