[Differential diagnosis of increased phenylalanine blood level in infancy. Results of the German collaborative study on phenylketonuria (PKU)/hyperphenylalaninemia (HPA)].
Between 1978 and 1984 165 children with elevated Phe blood levels in newborn screening were included in a German multicentric study. The differential diagnosis, comprising Phe concentrations in the blood under a tetrahydrobiopterin (BH4) load (30 mg BH4), determination of pterins in the urine and dihydropteridin reductase (DHPR) in erythrocytes, resulted in two patients with a 6-pyruvoyltetrahydrobiopterin synthase (PTPS) deficiency. Those patients with a defect in the apoenzyme phenylalanine hydroxylase (PH) were treated with a low Phe diet, when the Phe blood concentrations exceeded 10 mg/dl under an adapted formula (n = 154). At the age of six months, in 155 infants a protein challenge containing 180 mg Phe/kg body weight for three days was performed, followed by a fourth day with 5 mg Phe/kg. Corresponding to the US Collaborative Study [19] 3 types of response were chosen according to the course of the Phe blood level under the challenge (n = 145). Type I response (n = 112) shows a continuous increase of the Phe more than 20 mg/dl even under the Phe restriction at day 4. Type II response (n = 14) shows also increasing Phe blood levels above 20 mg/dl, followed by a spontaneous decrease below 20 mg/dl still during the high Phe challenge and even lower at the fourth day with low Phe intake. Type III response (n = 19) had only a small increase of the Phe blood concentration, mostly below 15 mg/dl during the whole challenge period.(ABSTRACT TRUNCATED AT 250 WORDS)
Schmidt
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Lutz
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Batzler
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D000429:Alcohol Oxidoreductases / Q000172:deficiency; D001708:Biopterins / Q000031:analogs & derivatives; D003937:Diagnosis, Differential; D005860:Germany, West; D006801:Humans; D007231:Infant, Newborn; D008403:Mass Screening; D010649:Phenylalanine / Q000097:blood*; D010651:Phenylalanine Hydroxylase / Q000172:deficiency; D010661:Phenylketonurias / Q000201:enzymology / Q000517:prevention & control*; D019761:Phosphorus-Oxygen Lyases
D001708:Biopterins; D010649:Phenylalanine; D000429:Alcohol Oxidoreductases; D010651:Phenylalanine Hydroxylase; D019761:Phosphorus-Oxygen Lyases; C043497:6-pyruvoyltetrahydropterin synthase; C003402:sapropterin
Differentialdiagnose des erhöhten Phenylalanin-Blutspiegels im Säuglingsalter. Ergebnisse der deutschen Verbundstudie über Phenylketonurie (PKU)/Hyperphenylalaninämie (HPA).