Efficacy of Phenylalanine- and Tyrosine-Restricted Diet in Alkaptonuria Patients on Nitisinone Treatment: Case Series and Review of Literature.

INTRODUCTION: Nitisinone used in alkaptonuria (AKU) can result in keratopathy due to strongly increased tyrosine levels. METHODS: This study aimed to investigate nutritional status and changes in plasma tyrosine and phenylalanine and urinary homogentisic acid (u-HGA) levels in 8 adult AKU patients (mean age, 56.3 ± 4.7 years) who were on tyrosine/phenylalanine-restricted diet together with 2 mg/day nitisinone. RESULTS: The treatment period was 23.4 ± 6.9 months. Daily dietary protein intake was restricted to 0.8-1.0 g/kg/day. Daily tyrosine intake was restricted to 260-450 mg/day for females and 330-550 mg/day for males. Tyrosine/phenylalanine-free amino acid supplements accounted for an average of 56.1% of daily protein intake. The following assessments were performed: anthropometric and plasma tyrosine level measurements every 2 months; ophthalmological examination every 6 months, and nutritional laboratory analyses and measurements of plasma amino acids and u-HGA once in a year. It was targeted to keep the plasma tyrosine level <500 µmol/L. The plasma tyrosine level was <100 µmol/L before the treatment in all patients and around a mean of 582.5 ± 194.8 µmol/L during the treatment. The diet was rearranged if a plasma tyrosine level of >700 µmol/L was detected. The u-HGA level before and after the 1st year of treatment was 1,429.3 ± 1,073.4 mmol/mol creatinine and 33.6 ± 9.5 mmol/mol creatinine, respectively. None of the patients developed keratopathy or experienced weight loss and protein or micronutrient deficiency. CONCLUSION: AKU patients should receive tyrosine/phenylalanine-restricted diet for reducing plasma tyrosine level to the safe range. Tyrosine/phenylalanine-free amino acid supplements can be safely used to enhance dietary compliance. Keratopathy and nutrient deficiency should be frequently monitored.

Serum Level of Biotin Rather than the Daily Dosage Is the Main Determinant of Interference on Thyroid Function Assays.

INTRODUCTION: Several case reports stress that high-dose biotin causes incorrect laboratory results. However, the extent of this interference in children is not systematically studied. AIM: To assess factors associated with biotin interference on thyroid function tests in subjects with biotinidase deficiency. METHOD: The study included 44 children who were treated with oral biotin (Group 1, median dose: 10 mg/day [25-75p; 10-10], age: 1.83 years [1.04-2.90]) and 30 healthy subjects (Group 2, age: 1.05 years [0.37-3.37]). Thyroid function tests were performed with two different assays, and streptavidin-coated particles were used in order to remove biotin from serum samples of cases with biotin interference. RESULTS: The measurements were first performed with Beckman Coulter. In Group 1, remarkably high levels of fT3 and fT4 were found in 26 (59.1%) and 25 (56.8%) patients, respectively. Thyroid hormone functions were all normal in Group 2. Significantly higher serum biotin levels were detected in interference-positive children (p < 0.001). The serum biotin levels in Group 1 showed a strong positive correlation with fT3 (r = 0.867, p < 0.001) and fT4 levels (r = 0.905, p < 0.001). A serum biotin level of 80.35 µg/L was found to be the best cut-off value for predicting interference (sensitivity: 96.2% and specificity: 94.4%). When analyzed with Siemens Advia Centaur XP, all thyroid function tests were normal in both groups except in one patient (2.27%) with slightly elevated fT3 level in Group 1. Repeated tests with Beckman Coulter after neutralization of biotin with streptavidin magnetic particles in serum samples of the interference-positive cases revealed normal thyroid hormone levels. CONCLUSION: Interference is an important problem in thyroid function tests in nearly 60% of all children receiving biotin treatment for biotinidase deficiency. Serum levels of biotin rather than the dosage are the main determinant of interference, which can be eliminated by choosing appropriate laboratory methods.

Vitamin/mineral and micronutrient status in patients with classical phenylketonuria.

BACKGROUND & AIMS: Strict low-phenylalanine diet is associated with an increased risk of developing micronutrient deficiencies in patients with phenylketonuria (PKU). The primary objective of this single-center, case-control study was to assess the nutritional parameters of patients with PKU on strict low-phenylalanine diet without vitamin and mineral supplementation compared to a healthy control group. Secondary objective was to identify the adequacy of vitamin/mineral supplementation in phenylalanine-free (Phe-free) amino acid formulas. METHODS: A total of 112 age- and sex-matched patients with PKU and 36 controls who did not take vitamin or mineral supplementation at least for the last 6 months were enrolled in the study. Biochemical and hematological markers including hemoglobin, serum vitamin B12, folic acid, iron, ferritin, transferrin saturation, copper, prealbumin, albumin, total protein, phosphorus, calcium, 25-hydroxy vitamin D, zinc, vitamin A and vitamin E levels were screened from fasting morning blood samples. RESULTS: One hundred and twelve patients with classical PKU (53 females, 47.3%) and 36 healthy controls (18 females, 50.0%) were enrolled in the study. The mean age of patients with PKU was 136.8 ± 82.1 months (18-377). Median serum vitamin B12 level of patients with PKU was found to be higher than the control group (p = 0.002). Vitamin B12 deficiency was 15.2% and 30.6% in patients with PKU and healthy controls, respectively (p = 0.040). Mean serum folic acid level was higher in patients with PKU than the control group (p < 0.0001). In 55.4% of patients with PKU, and 2.8% of the control group, serum folic acid level was above the reference range (p < 0.0001). The frequency of ferritin and prealbumin values above the reference range was found to be higher in patients with PKU compared to the control group (44.4% vs 16.9%, p = 0.001; 38.8% vs 22.1%, p = 0.020, respectively). 25-Hydroxy vitamin D deficiency was detected in 53.6% and 47.2% of patients with PKU and the control group, respectively. Mean serum copper level was higher in the well-controlled (114.3 ± 26.7 µg/dL) group than the poorly controlled group (101.0 ± 29.1 µg/dL) (p = 0.022). CONCLUSIONS: Phe-free amino acid formulas provide adequate vitamin A and zinc levels in patients with PKU, and result in excess folic acid, vitamin B12, copper and vitamin E values that are higher than required levels. Our results demonstrate a high percentage of vitamin D deficiency in patients with classical PKU and also in healthy controls in Turkey.

Severe hyperchylomicronemia in two infants with novel APOC2 gene mutation.

Background Familial apo C-II deficiency is a rare hereditary disorder frequently caused by lipoprotein lipase (LPL) and APOC2 gene mutations. To date, less than 30 patients with familial apo C-II deficiency with 24 different mutations have been identified in the literature. Here, we describe two familial chylomicronemia syndrome cases in infants with two novel mutations of the APOC2 gene. Case presentation Case 1, a 46-day-old female, was admitted to our hospital for evaluation due to the lipemic appearance of the blood sample. A clinical examination revealed hepatomegaly and lipemia retinalis. Triglyceride level of 6295 mg/dL was decreased with a strict low-fat diet, medium-chain triglycerides (MCT) oil-rich formula and omega-3 fatty acid supplementation. Due to low adherence to the diet, TG elevation was detected and fresh frozen plasma (10 mL/kg/day) was administered for 2 days. A novel homozygous p.Q25X (c.73C>T) mutation in the APOC2 gene was detected. Case 2, a 10-month-old female patient, referred to our center for the differential diagnosis of hyperlipidemia as her blood sample could not be assessed due to its lipemic appearance. Laboratory examinations showed a TG level of 4520 mg/dL which was reduced with a low-fat diet, MCT oil-rich formula and omega-3 fatty acid supplementation. Hepatosteatosis and splenomegaly were determined using abdominal sonography. A novel homozygous IVS2+6T>G (c.55+6T>G) mutation in the APOC2 gene was identified. Conclusions We describe two novel homozygous mutations (p.Q25X [c.73C>T] and IVS2+6T>G [c.55+6T>G]) in the APOC2 gene in infants with hyperchylomicronemia. To the best of our knowledge, Case 1 is the youngest patient with familial apo C-II deficiency in the literature to date.

The Effects of Breastfeeding in Infants With Phenylketonuria.

PURPOSE: In the early years of phenylketonuria (PKU) treatment, mothers and healthcare professionals often decide to discontinue breastfeeding after the diagnosis of PKU in infants. It was believed to be the only effective way to monitor the infant's intake and allow for precise titration and measurement of the intake of phenylalanine (Phe). In the early 1980s, with the determination of low concentration of Phe in breast milk, breast milk supplemented with Phe-free formula has become an acceptable dietary treatment for infants with PKU. Today, breastfeeding is encouraged and well established in PKU patients. The aim of the present study is to investigate the prevalence and duration of breastfeeding, the effect of breastfeeding on serum Phe levels, and weight gain in infants with PKU. DESIGN AND METHODS: Data were collected from chart reviews. Medical records of 142 children with PKU diagnosed via the national neonatal screening program were analyzed retrospectively. RESULTS: Of the 41 infants with complete medical records, 40 (97.6%) were breastfed following delivery whereas only one (2.4%) was bottle fed. After the diagnosis, breastfeeding was continued in 25 (61%) infants with phenylalanine-free amino acid based protein substitute. The mean duration of breastfeeding was 7.4±4.0 (1-15) months. Serum Phe concentration of breastfed infants (280±163 µmol/L) was significantly lower than non-breastfed infants (490±199 µmol/L) (p<0.001). Mean monthly weight gain in the first year of life was significantly higher in breastfed patients (493±159 g/month) compared to non-breastfed patients (399±116 g/month) (p=0.046). CONCLUSION: In the first year of life, weight gain and serum Phe levels were more favorable in breastfed infants with PKU compared to non-breastfed infants with PKU.

The Effect of Ketogenic Diet on Serum Selenium Levels in Patients with Intractable Epilepsy.

The aim of the present study was to evaluate serum selenium levels in children receiving olive oil-based ketogenic diet (KD) for intractable seizures for at least 1 year. Out of 320 patients who were initiated on KD, patients who continued receiving KD for at least 12 months were enrolled. Sixteen patients who had selenium deficiency at the time of starting KD were excluded. Finally, a total of 110 patients (mean age 7.3 ± 4.2 years) were included. Serum selenium levels were measured at baseline and at 3, 6, and 12 months after treatment initiation by using atomic absorption spectroscopy. Selenium deficiency was defined as a serum selenium level <48 µg/L at each visit. Repeated measure ANOVA with post hoc Bonferroni correction was used for data analysis. Mean duration of KD was 15.3 ± 4.3 months. Mean serum selenium levels were significantly lower at 6 and 12 months of KD treatment (66.2 ± 23.3 and 57.2 ± 16.2 µg/L, respectively) compared to pre-treatment levels (79.3 ± 25.7 µg/L) (p = 0.001). On the other hand, selenium levels did not show any significant difference at 3 months of KD treatment (70.0 ± 21.2 µg/L) compared to baseline levels (p = 0.076). A total of 54 patients (49.1%) were diagnosed with selenium deficiency, and oral selenium medication was initiated for these patients. No relevant clinical findings were detected, and echocardiographic findings were normal in all patients. The decline of the serum selenium concentrations after 6 and 12 months of ketogenic diet suggests that patients on this highly prescriptive dietary treatment need close monitoring of this trace element.

Fulminant hepatic failure and serum phosphorus levels in children from the western part of Turkey.

BACKGROUND/AIMS: Clinical and laboratory predictors of recovery in children with fulminant hepatic failure are limited. Recently, hypophosphatemia has been reported as a laboratory indicator of recovering liver function in children with fulminant hepatic failure . We aimed to determine the incidence of hypophosphatemia and its association with clinical outcome in children in our center with fulminant hepatic failure. METHODS: We analyzed 21 children who had been diagnosed with fulminant hepatic failure. Laboratory findings were recorded from admission date until the patient spontaneously recovered, underwent orthotopic liver transplantation or died. RESULTS: Eight patients (38%) died, 6 (28.6%) underwent orthotopic liver transplantation, and 7 (33.3%) recovered without orthotopic liver transplantation. We identified hypophosphatemia in 57.1% of children with fulminant hepatic failure. Serum phosphorus levels were significantly lower in patients who recovered than in the orthotopic liver transplantation+death group. The presence of encephalopathy was determined at a much lower rate in the recovery group than in the orthotopic liver transplantation+death group. Serum phosphorus concentration ≥2.9 mg/dl and presence of encephalopathy were identified as independent risk factors for mortality. CONCLUSIONS: Hypophosphatemia can be identified as a marker of recovery in children with fulminant hepatic failure. Presence of encephalopathy and a serum phosphorus level ≥2.9 mg/dl appear to indicate a poor prognosis in children with fulminant hepatic failure.

Severe iron overload and hyporegenerative anemia in a case with rhesus hemolytic disease: therapeutic approach to rare complications.

A 33 weeks' gestation, a baby with rhesus hemolytic disease (RHD), who had received intrauterine transfusions twice, developed cholestatic hepatic disease and late hyporegenerative anemia. Her serum ferritin and bilirubin levels increased to 8842 ng/ml and 17.9 mg/dl, respectively. Liver biopsy showed cholestasis and severe iron overload. Treatment with recombinant erythropoietin (rHuEPO) decreased the transfusion need, and intravenous deferoxamine resulted in a marked decreased in serum ferritin levels and normalization of liver function. In patients who have undergone intrauterine transfusions due to RHD, hyperferritinemia and late hyporegenerative anemia should be kept in mind. Chelation therapy in cases with symptomatic hyperferritinemia and rHuEPO treatment in cases with severe hyporegenerative anemia should be considered.