The 48-hour tetrahydrobiopterin loading test in patients with phenylketonuria: evaluation of protocol and influence of baseline phenylalanine concentration.

BACKGROUND: The 24- and 48-hour tetrahydrobiopterin (BH4) loading test (BLT) performed at a minimum baseline phenylalanine concentration of 400 µmol/l is commonly used to test phenylketonuria patients for BH4 responsiveness. This study aimed to analyze differences between the 24- and 48-hour BLT and the necessity of the 400 µmol/l minimum baseline phenylalanine concentration. METHODS: Data on 186 phenylketonuria patients were collected. Patients were supplemented with phenylalanine if phenylalanine was <400 µmol/l. BH4 20mg/kg was administered at T = 0 and T = 24. Blood samples were taken at T=0, 8, 16, 24 and 48 h. Responsiveness was defined as ≥ 30% reduction in phenylalanine concentration at ≥ 1 time point. RESULTS: Eighty-six (46.2%) patients were responsive. Among responders 84% showed a ≥ 30% response at T = 48. Fifty-three percent had their maximal decrease at T = 48. Fourteen patients had ≥ 30% phenylalanine decrease not before T = 48. A ≥ 30% decrease was also seen in patients with phenylalanine concentrations <400 µmol/l. CONCLUSION: In the 48-hour BLT, T = 48 seems more informative than T = 24. Sampling at T = 32, and T = 40 may have additional value. BH4 responsiveness can also be predicted with baseline blood phenylalanine <400 µmol/l, when the BLT is positive. Therefore, if these results are confirmed by data on long-term BH4 responsiveness, we advise to first perform a BLT without phenylalanine loading and re-test at higher phenylalanine concentrations when no response is seen. Most likely, the 48-hour BLT is a good indicator for BH4 responsiveness, but comparison with long term responsiveness is necessary.

[Influenza A pneumonia]. / Influenza-A-pneumonie.

The majority of influenza cases are not associated with complications. Secondary bacterial pneumonia, commonly caused by Streptococcus pneumoniae or Staphylococcus aureus, is well known to most clinicians. Primary influenza viral pneumonia, characterized by rapidly progressive hypoxia and respiratory insufficiency together with non-consolidating pulmonary infiltrates, has a high mortality rate. In 3 patients, a man aged 74 years, and two neonates aged 11 months and 4 weeks respectively, primary influenza A pneumonia was diagnosed. In the latter two patients the virus was cultivated from sputum. Despite intensive supporting and drug treatment, the first and the last patients died. In view of evolving therapeutic possibilities, notably regarding neuraminidase inhibitors, it is important that clinicians recognize this complication of influenza at an early stage.

Short-term efficacy and safety of pravastatin in 72 children with familial hypercholesterolemia.

The safety, tolerability, and efficacy of a 12-wk treatment with pravastatin, 5, 10, and 20 mg/d, was evaluated in 72 children with heterozygous familial hypercholesterolemia (FH) in a double-blind, randomized and placebo-controlled study. The results show that pravastatin was well tolerated and that adverse events were mild and equally distributed among the three treatment groups. Plasma total and LDL cholesterol levels were significantly reduced in all pravastatin treatment groups, in comparison with the control group; -24.6% (-28.1 to 21.0) and -32.9% (-37.0 to -28.6), for mean change and 95% confidence interval, respectively. In four children plasma LDL cholesterol levels were reduced within normal limits for sex and age. HDL cholesterol increased in the pravastatin 20-mg group, +10.8% (+3.4 to +18.8), whereas plasma apo B100 and very LDL (VLDL) cholesterol levels were reduced within all pravastatin-treated groups -26.8% (-31.2 [corrected] to -21.7) and -24.5% (-35.0 to -12.3). These data show that short-term pravastatin treatment of children with FH is safe and effective, although long-term dose titration studies with 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors need to be performed, to reduce plasma LDL cholesterol levels below a predefined level. The results of these studies have to be awaited before new treatment strategies are to be considered in these children.