Dorothy E.M. Francis

Challenge confirmation of late-onset reactions to extensively hydrolyzed formulas in infants with multiple food protein intolerance

BACKGROUND Many infants with cows milk protein intolerance have adverse reactions to soy, casein and whey hydrolysate formula and to other foods. The recent development of Neocate, a hypoallergenic, nutritionally complete infant formula composed of individual amino acids and other nutrients, has enabled these infants to be stabilized. OBJECTIVE We observed the effect of food challenges in infants with reported hypersensitivity to hypoallergenic formulas. METHODS Eighteen infants (median age, 7 1/2 months) were given Neocate formula for 2 months and then underwent a 7-day double-blind placebo-controlled challenge with the formula previously best tolerated. RESULTS In 12 of the 18 infants irritability, vomiting, diarrhea, and/or eczema flares developed during the formula challenge. In two patients symptoms developed immediately, but in the remainder adverse reactions evolved within 7 days (range, 4 to 7 days). Adverse reactions were to soy formula (six patients), whey hydrolysate (two), and casein hydrolysate (four). When infants were 12 months of age, parents reported adverse reactions after the ingestion of other low allergen foods (median, six; from a panel of 10 such foods). CONCLUSION A group of infants with late-onset adverse reactions to soy, extensively hydrolyzed casein, and whey formulas and to other foods has been identified. Neocate formula proved to be an effective substitute formula for these patients.

Reducing parenteral requirement in children with short bowel syndrome: impact of an amino acid-based complete infant formula.

BACKGROUND The aim of this study was to assess the impact of an amino acid-based complete infant formula on enteral feeding tolerance and parenteral nutrition requirement in children with severe short bowel syndrome. METHODS Four children (23 months-4.75 years) with short bowel syndrome who required long-term parenteral nutrition due to persistent feeding intolerance while receiving an extensively hydrolyzed formula were assessed before and after the commencement of an amino acid-based complete infant formula for a mean follow-up period of 48 months (range 39-51 months). Assessment included clinical monitoring of feeding tolerance and nutritional status, biochemistry, stool analysis, skin-prick testing to common food antigens, esophagogastroduodenoscopy and colonoscopy or jejunoscopy with biopsies, and measurement of disaccharidase levels and intestinal permeability. RESULTS All patients ceased parenteral nutrition within 15 months as a result of decreased stool output and resolution of vomiting. Patients had a reduction in hospitalization (mean: 198 versus 98 days/patient/year), episodes of proven (mean: 4.3 versus 3.3/patient/year) and suspected (mean: 6.5 versus 4.0/ patient/year) bacterial sepsis and central line insertions (mean: 2.5 versus 1.5/patient/year). Intestinal permeability to lactulose fell markedly (mean: 69% versus 2.7%). Disaccharidase levels increased in all three patients undergoing repeat studies. CONCLUSIONS An amino acid-based complete infant formula improved feeding tolerance and eliminated the need for parenteral nutrition in four children with short bowel syndrome who had previously required long-term parenteral nutrition. The clinical improvement was mirrored by improvement in measurements of intestinal function.

Are neuropsychological impairments in children with early-treated phenylketonuria (PKU) related to white matter abnormalities or elevated phenylalanine levels?

This study aimed to enhance our understanding of neuropsychological functioning in children with early-treated phenylketonuria (PKU) and assess the relative impact of white matter abnormalities (WMA) and neurotransmitter deficiencies on cognitive functions in this population. The study consisted of 33 children with early-treated PKU and 34 healthy control children aged between 7 to 18 years. All children had a neuropsychological evaluation that included measures of general intelligence, attention, processing speed, memory and learning, executive function, and academic achievement. Children in the PKU group also had a magnetic resonance (MR) brain scan. When compared with the control group, the PKU group exhibited global cognitive impairment including lower IQ, attention problems, slow information processing, reduced learning capacity, mild executive impairments, and educational difficulties. Children in the PKU group with extensive WMA (n = 14) displayed significant impairments across all cognitive domains. Metabolic control correlated weakly to moderately with attention, executive, and memory/learning factors. Within the PKU group, regressions revealed that executive function and attention factors were independently related to severity of WM pathology and age, while the memory and learning factor was independently related to metabolic control and age. It is concluded that children with early-treated PKU exhibit a global pattern of impairment, with a particular deficit in processing speed. WM pathology extending into frontal and subcortical regions correlates with the greatest deficits and a profile of impairment consistent with diffuse WM damage. Our findings also offer some support for dopamine depletion in the prefrontal cortex, however adverse consequences as a result of norepinephrine and serotonin deficiencies should not be discounted.

The natural history of intolerance to soy and extensively hydrolyzed formula in infants with multiple food protein intolerance.

Infants (n = 18) with intolerance to extensively hydrolyzed formulas and soy who responded to an L-amino acid-based elemental formula (AAF) were studied until 3 years of age. By 2 years of age most tolerated non-formula foods, and by 3 years only 3 required AAF. Growth normalized during AAF feeding in 4 infants with failure to thrive.

Neuropsychological functioning in children with early-treated phenylketonuria: Impact of white matter abnormalities

Impact of white matter abnormalities (WMAs) on neuropsychological functioning in children with early-treated phenylketonuria (ETPKU) was examined. Children with ETPKU (20 males, 12 females, mean age 11 years 2 months, SD 3 years 6 months) and controls (20 males, 14 females, mean age 10 years 4 months, SD 3 years 1 month) aged 7 to 18 years were assessed using tests of attention, processing speed, memory and learning, executive function, and academic achievement. Those with ETPKU, exhibiting WMAs extending into subcortical/frontal regions (n=14), displayed significant impairments in a number of domains. Children with ETPKU but no WMAs (n=6), or pathology restricted to the posterior periventricular region (n=12), displayed only mild deficits. Concurrent phenylalanine levels correlated weakly with cognitive parameters, whereas lifetime phenylalanine levels were associated with deficits in several cognitive domains. Impairments in children with extensive WMAs are consistent with compromised neural transmission, which is characterized by dysmyelination. However, children with no detectable, or mild WMAs, also displayed cognitive problems, indicating that neuropsychological functioning in children with ETPKU is determined by a complex interaction of biological and environmental factors.

Acute illness in maple syrup urine disease: Dynamics of protein metabolism and implications for management

Acute metabolic decompensation in maple syrup urine disease (MSUD) during otherwise minor illnesses has generally been presumed to result from massive release of leucine from protein catabolism. A stable isotope method based on the continuous infusion of (2H5)phenylalanine was used to measure protein metabolism in vivo in two children with MSUD during acute illness and when well. Net protein catabolism was greater in the unwell state (0.51 and 0.40 gm/kg per 24 hours in each child, respectively) than in the basal state (0.34 and 0.32). This rate of release of leucine from protein is compatible only with a slow (several days) rather than a dramatic rise in plasma leucine levels during acute illness in MSUD. Poor oral intake leading to a relative increase in time spent in the fasting state appears to be a more important determinant of increasing leucine levels than the catabolic effect of infection in itself. These factors suggested that branched-chain amino acid restriction should be commenced at the start of minor illness in children with MSUD, and that intake of other nutrients should be maintained or increased throughout the illness. A regimen based on these concepts was used during nine episodes of minor illness in two children with MSUD. Plasma branched-chain amino acid levels remained acceptable (less than 700 mumol/L) throughout each of these episodes. Dietary supplementation of this type may reduce the risk of metabolic decompensation during acute illnesses in children with MSUD.

Maternal tyrosinaemia II: management and successful outcome.

A 25-year-old woman with tyrosinaemia type II was treated from the 5th week of pregnancy with a protein-restricted diet supplemented with a tyrosine/phenylalanine-free amino acid mixture. Tyrosine concentrations were maintained in the range 100–200 μmol/l by restricting natural protein intake to 0.16 g/kg per 24h in early pregnancy, with increases up to 0.38 g/kg per 24h in the last trimester. This treatment maintained plasma phenylalanine concentrations in the range 20–40 μmol/l. Maternal weight gain and fetal growth were normal, and the mother remained asymptomatic throughout the pregnancy. A normal infant was born at term with length, weight and head circumference between the 25–50 th per centiles.

Three-year audit of the hyperphenylalaninaemia/phenylketonuria spectrum in Victoria.

Aim:  To determine the prevalence, the types and severity of hyperphenylalaninaemia (including phenylketonuria (PKU)) in Victoria and to report on a new treatment modality of PKU.

Body composition in young adults with inborn errors of protein metabolism—A pilot study

SummaryThe natural history of inborn errors of protein metabolism and the long-term effects of prescribed semisynthetic therapeutic diets are largely unknown. We assessed body composition, measuring body-fat mass and distribution, fat-free mass, total body protein, total body potassium, bone density and skeletal muscle mass, in young adults (age > 18 years; 6 female, 5 male) with inborn errors of protein metabolism maintained on long-term low-protein diets, compared with controls. Female patients were significantly shorter (159.4 cm vs 169.2 cm, p = 0.013) and had higher BMI (25.3 vs 22.0 kg/m2, p < 0.05), abdominal to gluteal circumference ratio (0.84 vs 0.73, p = 0.011), percentage body fat (42.3% vs 29.5%, p < 0.005) and ratio of central to peripheral body fat (1.15 vs 0.86, p < 0.05) than controls. Male patients had lower height-adjusted total body bone mineral content (0.9 vs 1.02 g/m2, p < 0.04) and skeletal muscle mass (31.1 vs 36.3 kg, p < 0.04) than controls. Compared with controls, patients’nitrogen index was significantly lower (0.91 vs 1.03, p < 0.01), consistent with lower total body protein. Potassium index was significantly higher (121.2% vs 110.4%, p < 0.03), consistent with higher body cell mass, or intracellular water. Documentation of body composition in larger patient series is important to elucidate whether these results reflect increased risks (hence opportunities for prevention) of bone disease, metabolic syndrome and cardiovascular disease in this population.

Pregnancy in Phenylketonuria: Dietary Treatment Aimed at Normalising Maternal Plasma Phenylalanine Concentration

The transport characteristics of the placenta, which favour higher phenylalanine concentrations in the fetus than in the mother, and regression data of head circumference at birth against phenylalanine concentration at conception in maternal phenylketonuria (PKU), suggest that treatment of maternal PKU should ideally aim to maintain plasma phenylalanine concentration within the normal range throughout pregnancy. A patient with classical PKU was treated from before conception by aiming to maintain plasma phenylalanine concentration within the range 50-150 mumol/l and tyrosine within the range 60-90 mumol/l. The diet was supplemented with phenylalanine-free amino acids (100-180 g/day) and tyrosine (0-5 g/day). Plasma amino acid concentrations were monitored weekly by amino acid analyser. Dietary phenylalanine intake ranged from 6 mg/kg/day at conception to 30 mg/kg/day at delivery. Normal weight gain and fetal growth were maintained throughout the pregnancy. A normal baby was born at term with a head circumference of 35.5 cm; at 1 year of age no abnormality is detectable. These results show that with careful monitoring and compliance it is possible, and may be advisable, to maintain plasma phenylalanine concentration within the normal range in the management of PKU pregnancy.