Effects of Short-Term Calcium Supplementation in Children and Adolescents with Phenylketonuria

A food pyramid for adult patients with phenylketonuria and a systematic review on the current evidences regarding the optimal dietary treatment of adult patients with PKU

Early dietary treatment is mind-saving in patients with phenylketonuria. A "diet-for-life" is advocated, aimed to prevent effects of chronic exposure to hyperphenylalaninemia. While adherence to diet is significant during childhood as patients are followed-up at specialized metabolic centers, during adolescence and adulthood percentage of patients discontinuing diet and/or lost at follow-up is still high. The process of passing skills and responsibilities from pediatric team to adult team is defined "transition". The goal of transition clinics is to set up specific multidisciplinary care pathways and guarantee continuity of care and compliance of patients to care. In 2017, "The complete European guidelines on phenylketonuria" were published. These guidelines, however, do not provide an easy way to illustrate to adult patients how to follow correct dietary approach. The purpose of this review is to evaluate current evidence on optimum dietary treatment of adults with phenylketonuria and to provide food pyramid for this population. The pyramid built shows that carbohydrates should be consumed every day (3 portions), together with fruits and vegetables (5 portions), extra virgin olive oil, and calcium water (almost 1 L/day); weekly portions can include 150 g potatoes walnuts and hazelnuts (20 g). At top of pyramid, there are two pennants. The green means that, based on individual metabolic phenotype and daily phenylalanine tolerance, patients need personalized supplementation (specific phenylalanine free amino acid mixtures, vitamins and omega 3 fatty acids); the one red indicates foods that are banned from diet (aspartame and protein foods exceeding individual dietary phenylalanine tolerance).

Burden of phenylketonuria in Latin American patients: a systematic review and meta-analysis of observational studies

Background

Phenylketonuria (PKU) is an inborn error of metabolism caused by a deficiency of the enzyme phenylalanine hydroxylase. If untreated, the complications of PKU lead to significant neucognitive and neuropsychiatric impairments, placing a burden on both the individual’s quality of life and on the healthcare system. We conducted a systematic literature review to characterize the impact of PKU on affected individuals and on healthcare resources in Latin American (LATAM) countries.

Methods

Searches of the global medical literature as well as regional and local medical literature up to September 2021. Observational studies on patients with PKU from any LATAM country. Pairs of reviewers independently screened eligible articles, extracted data from included studies, and assessed their risk of bias.

Results

79 unique studies (47 cross-sectional studies, 18 case series, 12 case reports, and two cohort studies) with a total of 4090 patients were eligible. Of these studies, 20 had data available evaluating early-diagnosed PKU patients for meta-analysis of burden outcomes. Intellectual disability in the pooled studies was 18% [95% Confidence Interval (CI) 0.04–0.38; I² = 83.7%, p = 0.0133; two studies; n = 114]. Motor delay was 15% [95% CI 0.04–0.30; I² = 74.5%, p = 0.0083; four studies; n = 132]. Speech deficit was 35% [95% CI 0.08–0.68; I² = 93.9%, p < 0.0001; five studies; n = 162].

Conclusions

There is currently evidence of high clinical burden in PKU patients in LATAM countries. Recognition that there are many unmet neuropsychological needs and socioeconomic challenges faced in the LATAM countries is the first step in planning cost-effective interventions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02450-2.

Similarities and differences in key diagnosis, treatment, and management approaches for PAH deficiency in the United States and Europe

Background

Individuals with phenylalanine hydroxylase (PAH) deficiency lack an enzyme needed to metabolize the amino acid, phenylalanine. This leads to an increase of phenylalanine in the blood, which is associated with changes in cognitive and psychological functioning. Skilled clinical management is essential for preventing complications and providing comprehensive care to patients. In the last decade, the American College of Genetics and Genomics (ACMG) and a group of European experts developed separate guidelines to provide recommendations for the management and care of persons with PAH deficiency. The purpose of this paper was to compare and contrast these guidelines in order to understand the different approaches to PAH deficiency care.

Methods

We examined the procedures used to develop both guidelines, then evaluated key areas in PAH deficiency care which included screening, diagnostic approaches, dietary treatment (initiation and duration), ongoing phenylalanine level/ nutritional monitoring, neurocognitive screening, adherence issues in treatment, and special populations (women and maternal PKU, late or untreated PAH deficiency, and transitioning to adult services). We conducted a scoping review of four key topics in PAH deficiency care to explore recent research studies performed since the publication of the guidelines.

Results

The ACMG and European expert group identified limited numbers of high quality studies to use as evidence for their recommendations. The ACMG and European guidelines had many similarities in their respective approaches PAH deficiency care and recommendations for the diagnosis, treatment, and management for persons with PAH deficiency. There were also a number of differences between the guidelines regarding the upper range for phenylalanine levels in adolescents and adults, the types of instruments used and frequency of neuropsychiatric examinations, and monitoring of bone health. Treatment adherence can be associated with a number of challenges, such as aversions to medical foods and formulas, as well as factors related to educational, social, and psychosocial issues. From the scoping review, there were many new studies addressing issues in treatment and management including new research on sapropterin adherence and increased dietary protein tolerance and pegvaliase on the reduction in phenylalanine levels and hypersensitivity reactions.

Conclusions

In the last decade, ACMG and European experts developed comprehensive guidelines for the clinical management of phenylalanine hydroxylase deficiency. The guidelines offered background and recommendations for clinical care of patients with PAH deficiency throughout the lifespan. New research evidence is available and updates to guidelines can keep pace with new developments. Evidence-based guidelines for diagnosis and treatment are important for providing expert care to patients.

Nutritional and metabolic parameters of children and adolescents with phenylketonuria

BACKGROUND AND AIMS

Considering that phenylalanine-poor diets may be monotonous and compromise the development and nutritional status of children and adolescents with phenylketonuria, the aim of this study was to evaluate the anthropometric and biochemical characteristics of children and adolescents with this condition.

METHODS

Retrospective study with anthropometric and biochemical data collection from patients with phenylketonuria in the age group 2-19.9 years. Nutritional status was classified according to the World Health Organization. Biochemical tests were compared to current recommendations.

RESULTS

A total of 84 patients (71.8%) were eligible, with a median age of 10.7 years (2.4-19.9 years). There was predominance of adequate (n = 58, 69%) with presence of overweight and obesity in 24 (28.5%) patients. The biochemical tests revealed hyperphosphatemia in 46 (55%), hypertriglyceridemia in 27 (50%), vitamin B12 elevated in 34 (41.2%), selenium deficiency in 10 (13.7%), insufficient zinc in 7 (8.9%), low globulin in 21 (26.9%), low HDL in 35 (59.3%) and elevated phenylalanine level in 28 (34.5%) patients in the sample. Overweight and obesity were correlated with low HDL (p = 0.04) and lowest adequate frequency of LDL (p = 0.09). Higher phosphorus values were associated with lower body weight (r = -0.72) and age (r = -0.75), as well as vitamin B12 in the same parameters (r = -0.67 and r = -0, 68). A positive correlation of phenylalanine with body weight and age (r = 0.62 and r = 0.66) was observed.

CONCLUSION

Most patients presented adequate according to anthropometric parameters and appropriate biochemical tests, except HDL, and moderate metabolic control of the disease. However, attention should be paid to the presence of overweight and need for biochemical monitoring of triglycerides, selenium, zinc, HDL, and phenylalanine.

Sex differences in body composition and bone mineral density in phenylketonuria: A cross-sectional study

Background

Low bone mineral density (BMD) and subsequent skeletal fragility have emerged as a long-term complication of phenylketonuria (PKU).

Objective

To determine if there are differences in BMD and body composition between male and female participants with PKU.

Methods

From our randomized, crossover trial [1] of participants with early-treated PKU who consumed a low-phenylalanine (Phe) diet combined with amino acid medical foods (AA-MF) or glycomacropeptide medical foods (GMP-MF), a subset of 15 participants (6 males, 9 females, aged 15-50 y, 8 classical and 7 variant PKU) completed one dual energy X-ray absorptiometry (DXA) scan and 3-day food records after each dietary treatment. Participants reported lifelong compliance with AA-MF. In a crossover design, 8 participants (4 males, 4 females, aged 16-35 y) provided a 24-h urine collection after consuming AA-MF or GMP-MF for 1-3 weeks each.

Results

Male participants had significantly lower mean total body BMD Z-scores (means ± SE, males = - 0.9 ± 0.4; females, 0.2 ± 0.3; p = 0.01) and tended to have lower mean L1-4 spine and total femur BMD Z-scores compared to female participants. Only 50% percent of male participants had total body BMD Z-scores above - 1.0 compared to 100% of females (p = 0.06). Total femur Z-scores were negatively correlated with intake of AA-MF (r = - 0.58; p = 0.048). Males tended to consume more grams of protein equivalents per day from AA-MF (means ± SE, males: 67 ± 6 g, females: 52 ± 4 g; p = 0.057). Males and females demonstrated similar urinary excretion of renal net acid, magnesium and sulfate; males showed a trend for higher urinary calcium excretion compared to females (means ± SE, males: 339 ± 75 mg/d, females: 228 ± 69 mg/d; p = 0.13). Females had a greater percentage of total fat mass compared to males (means ± SE, males: 24.5 ± 4.8%, females: 36.5 ± 2.5%; p = 0.047). Mean appendicular lean mass index was similar between males and females. Male participants had low-normal lean mass based on the appendicular lean mass index.

Conclusions

Males with PKU have lower BMD compared with females with PKU that may be related to higher intake of AA-MF and greater calcium excretion. The trial was registered at www.clinicaltrials.gov as NCT01428258.