Search Results (49)

Background/Objectives: Skeletal impairment has been reported as a common finding in Hyperphenylalaninemia (HPA)/Phenylketonuria (PKU) patients regardless of age and method of diagnosis, both in children and adults. Quantitative Ultrasound (QUS) is a radiation-free and low-cost method for assessing bone quality, used in various chronic conditions. Methods: Bone quality was evaluated using a calcaneal QUS device. Auxological parameters, nutritional intakes, and plasma levels of key bone biomarkers were also registered. The population was divided into four groups: PKU patients under diet therapy and HPA patients on a free diet, both divided into receiving or not receiving single vitamin D supplementation. Results: All HPA/PKU patients had median bone quality index (BQI) Z- and T-score values lower than −1, with slightly better values in HPA children and PKU-supplemented adults. Dietary vitamin D intake in PKU patients was significantly higher than in HPA subjects (p < 0.001), due to protein substitute supplementation. However, plasma 25(OH) vitamin D levels, although increased compared to baseline, were still overlapping among groups (p = 0.845) after supplementation. Approximately a quarter of both pediatric and adult non-supplemented PKU patients had Z-score and T-score levels below −2, and this percentage decreased with vitamin D supplementation in all groups. In PKU-supplemented patients, the Broadband Ultrasound Attenuation (BUA) was significantly higher than in the other groups (p = 0.040). Conclusions: The improvement in BUA may represent preliminary evidence of the effect of vitamin D on bone architecture, which could encourage this supplementation to prevent the worsening of bone structure and reduce the risk of fractures. Full article

Background: Phenylketonuria (PKU) is a rare autosomal recessive metabolic disorder caused by mutations in the phenylalanine hydroxylase (PAH) gene, leading to hyperphenylalaninemia (HPA). Untreated, elevated phenylalanine (Phe) levels cause severe neurocognitive, developmental, and psychiatric complications. Management relies on a Phe-restricted diet, which is challenging to maintain, particularly in adolescents and adults. Sapropterin dihydrochloride, a synthetic form of tetrahydrobiopterin (BH4), can enhance residual PAH activity, lowering blood Phe levels and increasing dietary tolerance in responsive patients. However, real-world alignment with best practices remains underexplored. This study aims to report a tertiary referral center’s experience with sapropterin treatment in PKU and assess adherence to international guidelines. Methods: We retrospectively analyzed 23 PKU patients treated with sapropterin from 2007 to 2025. Patients with baseline Phe levels of 360–2000 µmol/L underwent a 10 mg/kg/day loading test over two weeks. Responsiveness was defined as a ≥30% reduction in blood Phe levels. Phe levels were measured pre- and post-test, and dietary tolerance was evaluated. Adherence to best practices was critically reviewed. Results: All patients showed significant Phe reductions (mean 71.43%, p < 0.0001), exceeding responsiveness thresholds. Most achieved substantial increases in dietary Phe tolerance, with three patients partially responsive (800–1200 mg/day). Responsiveness was unrespectful of the patient’s genotype, for those individuals for whom this was known (8/23 patients). Although effective, the test dose and duration differed from guideline recommendations (20 mg/kg/day). Neuropsychological and QoL assessments were not systematically performed, representing a key limitation. Conclusions: Sapropterin dihydrochloride effectively identified responders and improved dietary flexibility even with lower dosing protocols. Greater adherence to international standards, particularly regarding long-term neuropsychological monitoring, is needed to optimize patient care. Full article

Background: The rate at which amino acids (AAs) are absorbed from casein glycomacropeptide (CGMP) when given as a protein substitute in phenylketonuria (PKU) is unknown. This three-way randomised, controlled, crossover study aimed to compare the AA absorption profile of phenylalanine (Phe)-free L-amino acids (L-AAs), low-Phe CGMP (CGMP) and casein in healthy adult subjects. Methods: Area under the curve (AUC) was measured over 240 minutes after ingesting one dose of each protein source on three separate occasions, under the same test conditions. A total of 0.4 g/kg protein equivalent of each test product (L-AA, CGMP and casein) was given. Fasted blood samples were collected from healthy volunteers at 30, 60, 90, 120, 150, 180 and 240 minutes post-test. Insulin, blood urea nitrogen, glucose and total (TAAs), essential (EAAs), large neutral (LNAAs) and branch chain (BCAAs) amino acids were measured at each time point. Results: A total of 20 subjects (11 females), median age 43 y (range 23–49), with a median BMI 24.2 (20–30.5) were recruited. AUC was compared across groups. Statistically significant differences were noted for: AUC for TAAs and BCAAs between CGMP and L-AAs vs. casein [TAAs p = 0.008 and p = 0.03; BCAAs p = <0.001 and p = 0.002]. There were no AUC differences between L-AAs and CGMP. AUC was largest for L-AAs, then CGMP and finally casein. For LNAAs, EAAs, insulin, glucose and urea, there were no statistically significant differences. There was a consistent delivery of AAs for casein demonstrated by a sustained curve, but the absorption curves for L-AAs and CGMP were transient, rising rapidly and falling, with the exception of tyrosine with CGMP which showed a gradual increase over 240 minutes in contrast to L-AAs and casein. Conclusions: Amino acids from CGMP and L-AAs were absorbed more rapidly than casein, inferring CGMP did not mimic casein, a slow-release protein source. The tyrosine concentration curve for CGMP suggests a beneficial effect on the Phe: tyrosine ratio. Kinetic labelled studies will help bring greater understanding on the utilisation of AAs particularly important for protein synthesis. Full article

Pathogenic variants in the phenylalanine hydroxylase gene can result in phenylalanine (Phe) accumulation leading to phenylketonuria (PKU; OMIM #261600), a metabolic disease diagnosed in newborn screening. Early treatment with a Phe-restricted diet prevents severe mental retardation. Next to several other health complaints, patients with PKU present with low bone mineral density (BMD) more often than the general population. The etiology of the phenotype is not yet fully understood, and current research focuses on improving special medical foods and changes in osteoclasts (OC) and osteoblasts. Analysis of osteoclastic and oxidative stress control gene expression next to the simple number of OC developing from peripheral blood mononucleated cells (PBMCs) in association with dietary compliance and BMD was therefore part of our analysis. PBMCs were obtained from 17 adults with PKU and 17 age- and sex-matched controls on the same day. PBMCs were differentiated into osteoclasts (OC, Trap-positive multi-nucleated cells (≥3 nuclei)) for 14 days by adding human macrophage colony-stimulating factor (MCSF) and receptor activator of NF-κB Ligand (RANKL). Subsequently, quantitative real-time PCR was performed on OC function and oxidative stress control. Data on dietary compliance during the previous 12 months and 5 years and BMD were collected. PBMCs from adults with PKU and controls were differentiated into comparable numbers of OC (PKU: 53 [17–87] vs. controls: 39 [19–52], p = 0.381) without differences in mRNA expression of genes related to OC function and oxidative stress control. Dietary compliance in short-term and mid-term was not associated with OC number or mRNA expression, but CTSK negatively correlated with BMD T-Score in the hips of adults with PKU (Spearman r = −0.518, p = 0.040). Osteoclastogenesis was not changed in adult patients with PKU, nor were most mRNA expressions of OC marker genes or those of oxidative stress control. However, 44% of patients presented with BMD below −1 in their hips, and the OC of these tended to express higher CTSK (above −1: 0.2 [0.2–0.8] vs. below −1: 0.9 [0.6–3.4], p = 0.055). Thus, alternative regulatory mechanisms of OC activity may play a role in the development of low BMD in patients with PKU. Full article

Background: Phenylketonuria (PKU) is a rare metabolic disorder requiring lifelong dietary treatment. Adolescents and young adults face unique challenges in managing the condition, often compromising adherence and psychological well-being. This study aimed to explore coping strategies used by patients to manage their condition and their associations with dietary adherence, PKU-related symptoms, and quality of life (QoL) in young individuals with PKU. Methods: A cross-sectional study was conducted with 21 adolescents and young adults (13–25 years) with classical PKU, followed at the Unit of Inherited Metabolic Diseases in Padua, Italy. Participants completed questionnaires assessing dietary adherence, QoL, and coping. Biochemical data were collected from medical records. Results: Only 57.1% fully adhered to the diet; social barriers like embarrassment and school/work environments hindered adherence. Adolescents reported more irritability and concentration difficulties, while young adults reported greater fatigue. QoL was moderately impacted. Avoidance coping was more frequent in young adults and correlated with irritability and lower QoL. Transcendence-oriented coping was linked to fewer insomnia symptoms. Conclusions: Coping strategies influence symptom experience and QoL in PKU. Integrating psychological support and personalized care into routine treatment is essential to improve adherence and support patients through the transition to adulthood. Full article

Background/Objectives: Phenylketonuria (PKU) is a rare inherited metabolic disorder caused by phenylalanine hydroxylase deficiency, resulting in highly elevated blood phenylalanine (Phe) concentrations, leading to neurotoxic effects. Despite advancements in treatment, adult patients with PKU may experience impairments in executive functions (EFs). This study investigates the influence of metabolic control across different life stages on EFs and sociodemographic outcomes in adult PKU. Methods: We conducted a monocentric study with 36 early-diagnosed and treated PKU patients (mean age: 34.8 years). EFs were assessed using the Test Battery for Attentional Performance (TAP) and the Tower of London (TL-D). Metabolic data were extracted from medical records, focusing on childhood and adulthood metabolic control, including Phe fluctuations. Sociodemographic data were collected via questionnaires. Statistical analyses explored relationships between EFs, metabolic control, and sociodemographic data. Results: EFs in the cohort were within the lower average range. Significant negative correlations could be observed between EF performance and dried blood Phe concentrations during childhood (ages 0–10 years) as well as current Phe concentrations and Phe variation. Elevated childhood Phe concentrations were associated with lower educational attainment. Sociodemographic characteristics, such as employment status and living arrangements, aligned with those of the general population. Conclusions: Optimal cognitive development in PKU requires good metabolic control, particularly in early childhood. In adulthood, while dietary restrictions may be relaxed, maintaining low and stable Phe concentrations is crucial for EFs. Consistent monitoring and tailored therapeutic approaches throughout life seem essential for optimizing metabolic and neurocognitive outcome in PKU. Full article

Background: Maternal phenylketonuria (PKU), a metabolic disorder caused by defective phenylalanine hydroxylase activity, requires strict lifelong dietary management to prevent toxic phenylalanine accumulation. During pregnancy, non-adherence to a low-phenylalanine diet can lead to maternal PKU syndrome, resulting in severe neonatal complications, including microcephaly, congenital heart defects, and growth restrictions. Despite advances in metabolic management and preconception care guidelines, adherence remains a significant challenge, particularly among adults transitioning out of pediatric care. This case report examines the clinical consequences of dietary non-adherence in maternal PKU, highlighting the importance of preconception education, metabolic monitoring, and multidisciplinary care in preventing adverse neonatal outcomes. Methods: Using the CARE guidelines, we present the clinical course of a male neonate born to a mother with untreated PKU. Results: The analysis incorporates maternal dietary history, prenatal care details, and neonatal outcomes. Additionally, a review of current literature on maternal PKU management and outcomes contextualizes the findings. The neonate, delivered at 38 weeks via cesarean section, exhibited low birth weight (2150 g), severe microcephaly (head circumference: 28 cm), microphthalmia, and septal heart defects. Maternal dietary non-adherence, beginning in late adolescence, contributed to significantly elevated phenylalanine levels during pregnancy (>20 mg/dL). Prenatal care was initiated in the 23rd week of gestation, delaying dietary intervention. The mother reported limited understanding of the teratogenic risks associated with poor dietary control, which was compounded by gaps in preconception counseling and care continuity. Conclusions: This case underscores the critical need for comprehensive preconception education and lifelong metabolic management for women with PKU. Early and sustained dietary adherence is essential to mitigate neonatal risks. Public health initiatives should prioritize access to preconception care, enhance patient education, and establish robust multidisciplinary support systems to optimize maternal and neonatal outcomes. Addressing barriers such as delayed care initiation and limited dietary support can significantly reduce the burden of maternal PKU syndrome. Full article

Background: Special low-protein foods are essential in the dietary treatment of phenylketonuria (PKU). In the UK, these are available on prescription through the General Practitioners (GPs) and distributed via nutritional home delivery companies or pharmacies. Methods: A 58-item online non-validated semi-structured questionnaire was emailed to British Inherited Metabolic Disease Group (BIMDG) dietitians and dietetic support workers (DSW)/administrators working in PKU to ascertain the main system issues and errors with the supply of low-protein prescription foods (LPPF). Results: 73% (n = 53/73) of dietitians and 72% (n = 18/25) of DSW/administrators responded. A total of 80 questionnaires (representing 44 paediatric and 36 adult PKU centres) were completed. A total of 50% (n = 40/80) of respondents reported patient/caregiver problems accessing LPPF at least weekly. The most common problems were unavailable products (82%), missing LPPF in deliveries (79%), and delayed deliveries (66%). For 64% of respondents, >25% of their patients had recurring problems accessing LPPF, and 69% of respondents spent ≥1 h/week and 11% >5 h/week correcting LPPF patient supply issues. The most common foods patients experienced supply issues with were bread (96%), pasta/rice (41%) and milk replacements (35%). This was associated with GP prescription errors (65%), LPPF prescriptions sent to incorrect dispensers/suppliers (60%), and manufacturer supply issues (54%). Problems with patients/caregivers included not ordering LPPF in a timely way (81%), not responding to messages from home delivery companies (73%) and poor understanding of the ordering process (70%). The majority (93%) of respondents reported that prescription issues impacted their patients’ blood Phe control. Suggestions for improving access to LPPF included centralisation of the system to one supplier (76%) and apps for ordering LPPF (69%). Conclusions: The supply of LPPF for PKU in the UK is problematic; it may adversely affect the ability of patients to adhere to dietary management, and a review investigating patient access to LPPF is urgently required. Full article

Background: Maternal phenylketonuria (PKU) syndrome, leading to severe psychomotor retardation, microcephaly, cardiac defects and undergrowth, affects the unborn children of mothers with PKU with insufficient metabolic control during pregnancy. To improve long-term outcomes, a specific prevention program was developed. Methods: We designed a group training program for young women with PKU (>14 years) and their partners. Knowledge regarding PKU therapy and pregnancy was evaluated by a specifically developed multiple-choice questionnaire. In addition, scores of anxiety and depression were evaluated. Results: Patients (n = 20) and their partners (n = 13) significantly improved their knowledge after participation (correct answers: patients—86% vs. 90%, p = 0.003; partners—78% vs. 89%, p = 0.012). Females significantly improved their knowledge about diet (90% vs. 100%, p = 0.035) and metabolism (91% vs. 100%, p = 0.016), but not concerning gynecological topics. Patients’ median depression scores were within the normative range, with a slight decrease over time (6 points vs. 4 points, p = 0.836). Patients’ anxiety score remained stable over time (5.5 vs. 5, p = 0.247). Of trained mothers with PKU, four pregnancies with ideal metabolic control and healthy offspring could be observed. Conclusion: We suggest the inclusion of specific training programs in the standard care of female young adults with PKU, including for their partners. Full article

Background/Objectives: Phenylketonuria is a hereditary metabolic disorder characterized by a deficiency of phenylalanine hydroxylase. The main treatment for PKU is a phenylalanine-restricted diet. The exclusion of protein rich natural foods and inclusion of low-Phe substitutes may give rise to an imbalanced diet, and the increased risk of overweight and obesity in PKU is a cause for concern. We aimed to evaluate the body composition and nutritional biochemical biomarkers in adult PKU patients who are on Phe-restricted and essential amino acid-supplemented nutrition therapy and to investigate the relationships between these parameters and patient gender, adherence to dietary therapy, and disease type, defined as mild or classic PKU. Methods: The study group comprised 37 PKU patients and 26 healthy siblings as controls. The participants were assessed based on an analysis of anthropometric parameters, body composition, and biochemical test results. Results: PKU patients do not have a higher incidence of overweight and obesity than healthy controls, the proportion of energy derived from carbohydrates in their diets was below the recommended level, and their total energy intake was below the recommended daily allowance. It was remarkable that patients with a treatment adherence ratio of <50% displayed a higher prevalence of overweight and abdominal obesity in comparison to those with a more favorable treatment adherence ratio. Conclusions: In view of the growing prevalence of overweight in the general population, PKU patients should be kept under close long-term follow-up. Particularly in the group with low treatment compliance, more caution should be taken in terms of adverse outcomes. Full article

Background: Data suggest that metabolites, other than blood phenylalanine (Phe), better and independently predict clinical outcomes in patients with phenylketonuria (PKU). Methods: To find new biomarkers, we compared the results of untargeted lipidomics and metabolomics in treated adult PKU patients to those of matched controls. Samples (lipidomics in EDTA-plasma (22 PKU and 22 controls) and metabolomics in serum (35 PKU and 20 controls)) were analyzed using ultra-high-performance liquid chromatography and high-resolution mass spectrometry. Data were subjected to multivariate (PCA, OPLS-DA) and univariate (Mann–Whitney U test, p < 0.05) analyses. Results: Levels of 33 (of 20,443) lipid features and 56 (of 5885) metabolite features differed statistically between PKU patients and controls. For lipidomics, findings include higher glycerolipids, glycerophospholipids, and sphingolipids species. Significantly lower values were found for sterols and glycerophospholipids species. Seven features had unknown identities. Total triglyceride content was higher. Higher Phe and Phe catabolites, tryptophan derivatives, pantothenic acid, and dipeptides were observed for metabolomics. Ornithine levels were lower. Twenty-six metabolite features were not annotated. Conclusions: This study provides insight into the metabolic phenotype of PKU patients. Additional studies are required to establish whether the observed changes result from PKU itself, diet, and/or an unknown reason. Full article

A phenylalanine-restricted diet, supplemented with protein substitutes (PSs), remains the cornerstone of phenylketonuria (PKU) management. However, adherence is challenging in adulthood, and data on the nutritional status of early and continuously treated adults with PKU (ETAwPKU) are scarce. A total of 34 ETAwPKU (16 females; mean ± SD, age: 28 ± 9 years, phenylalanine concentration: 847 ± 285 µmol/L) and 34 age- and sex-matched control subjects were compared regarding their blood nutrient status, self-reported dietary intake, and cognitive wellbeing. Though diet adherence varied, all ETAwPKU were taking a PS. No significant differences were found for blood DHA, calcium, ferritin, transferrin, and zinc concentrations. However, selenium and ubiquinone concentrations were 16% and 29% lower in ETAwPKU, respectively (p < 0.01 and <0.0001). Vitamin concentrations (D, B12, B6, and folic acid) were significantly higher in ETAwPKU except for alpha-tocopherol. Amino acid (AA) concentrations differed between ETAwPKU and controls: they were significantly lower for 12 AAs and higher for phenylalanine and glycine. ETAwPKU had a significantly higher intake of most minerals and vitamins, except for niacin and phosphorus (no difference). Depending on the nutrient, PSs represented 52–100% of patients’ daily intake and 19% of total daily energy intake. Compared with controls, ETAwPKU scored significantly lower in three of the four subscales of the cognitive wellbeing questionnaire. Overall, the blood DHA and micronutrient status of ETAwPKU was adequate, except for selenium, with higher intakes than controls for most micronutrients. Patients relied heavily on PSs to meet the recommended intakes for protein, DHA, and micronutrients. The potential clinical impact of differences found in AA status should be further studied. Full article

Background: In 2011, a European phenylketonuria (PKU) survey reported that the blood phenylalanine (Phe) levels were well controlled in early life but deteriorated with age. Other studies have shown similar results across the globe. Different target blood Phe levels have been used throughout the years, and, in 2017, the European PKU guidelines defined new targets for blood Phe levels. This study aimed to evaluate blood Phe control in patients with PKU across Europe. Methods: nine centres managing PKU in Europe and Turkey participated. Data were collected retrospectively from medical and dietetic records between 2012 and 2018 on blood Phe levels, PKU severity, and medications. Results: A total of 1323 patients (age range:1–57, 51% male) participated. Patient numbers ranged from 59 to 320 in each centre. The most common phenotype was classical PKU (n = 625, 48%), followed by mild PKU (n = 357, 27%) and hyperphenylalaninemia (HPA) (n = 325, 25%). The mean percentage of blood Phe levels within the target range ranged from 65 ± 54% to 88 ± 49% for all centres. The percentage of Phe levels within the target range declined with increasing age (<2 years: 89%; 2–5 years: 84%; 6–12 years: 73%; 13–18 years: 85%; 19–30 years: 64%; 31–40 years: 59%; and ≥41 years: 40%). The mean blood Phe levels were significantly lower and the percentage within the target range was significantly higher (p < 0.001) in patients with HPA (290 ± 325 μmol/L; 96 ± 24%) and mild PKU (365 ± 224 μmol/L; 77 ± 36%) compared to classical PKU (458 ± 350 μmol/L, 54 ± 46%). There was no difference between males and females in the mean blood Phe levels (p = 0.939), but the percentage of Phe levels within the target range was higher in females among school-age children (6–12 years; 83% in females vs. 78% in males; p = 0.005), adolescents (13–18 years; 62% in females vs. 59% in males; p = 0.034) and adults (31–40 years; 65% in females vs. 41% in males; p < 0.001 and >41 years; 43% in females vs. 28% in males; p < 0.001). Patients treated with sapropterin (n = 222) had statistically significantly lower Phe levels compared to diet-only-treated patients (mean 391 ± 334 μmol/L; percentage within target 84 ± 39% vs. 406 ± 334 μmol/L; 73 ± 41%; p < 0.001), although a blood Phe mean difference of 15 µmol/L may not be clinically relevant. An increased frequency of blood Phe monitoring was associated with better metabolic control (p < 0.05). The mean blood Phe (% Phe levels within target) from blood Phe samples collected weekly was 271 ± 204 μmol/L, (81 ± 33%); for once every 2 weeks, it was 376 ± 262 μmol/L, (78 ± 42%); for once every 4 weeks, it was 426 ± 282 μmol/L, (71 ± 50%); and less than monthly samples, it was 534 ± 468 μmol/L, (70 ± 58%). Conclusions: Overall, blood Phe control deteriorated with age. A higher frequency of blood sampling was associated with better blood Phe control with less variability. The severity of PKU and the available treatments and resources may impact the blood Phe control achieved by each treatment centre. Full article

Morphofunctional assessment was developed to evaluate disease-related malnutrition. However, it can also be used to assess cardiometabolic risk, as excess adiposity increases this risk. Phenylketonuria (PKU) is the most prevalent inherited metabolic disease among adults, and obesity in PKU has recently gained interest, although fat mass correlates better with cardiometabolic risk than body mass index. In this systematic review, the objective was to assess whether adult patients with PKU have higher fat mass than healthy controls. Studies of adult PKU patients undergoing dietary treatment in a metabolic clinic reporting fat mass were included. The PubMed and EMBASE databases were searched. Relevance of articles, data collection, and risk of bias were evaluated by two independent reviewers. Ten articles were evaluated, six with a control group, including 310 subjects with PKU, 62 with mild hyperphenylalaninemia, and 157 controls. One study reported a significant and four a tendency towards an increased fat mass in all patients or only females with PKU. Limitations included not having a healthy control group, not reporting sex-specific results and using different techniques to assess fat mass. Evaluation of fat mass should be included in the morphofunctional assessment of cardiometabolic risk in adult patients with PKU. Full article

Background: To achieve a normal nutritional status, patients suffering from phenylketonuria (PKU) are typically prescribed amino acid (AA) supplements with low or no phenylalanine (Phe) content. Studies evaluating patient preferences regarding the intake modalities of AA supplements are limited. This study aimed to collect real-world data regarding prescription adherence and intake modalities of AA supplements reported by PKU patients while monitoring metabolic control. Methods: This cross-sectional study included 33 PKU patients (16 female and 17 male) with a mean age of 27.2 years. Questionnaires were provided to assess information on AA supplement intake, such as prescription adherence rate, frequency and timing of administration, supplement formulation, and combination with food or drinks. Plasma phenylalanine levels were monitored during the study period. Results: 51.5% (n = 17) of patients reported to lay within an adherence range of 75–100%. The majority of patients consumed AA supplements twice daily, with breakfast (87.9%) and afternoon snacks (51.5%). Powder supplements were most commonly used (72.7%) and often combined with milk and/or fruit juices (45.4%). Conclusions: Despite the known concerns related to treatment compliance among PKU adolescents and adults, most of the study participants reported a high level of adherence to AA supplement prescription. The personalized dietary regimens followed by the patients included in the current study represent a treatment approach that might be worth trying in non-compliant patients. Full article