Phenylketonuria VIII. Relation between Age, Serum Phenylalanine Level, and Phenylpyruvic Acid Excretion.

Armstrong, Marvin D.; Low, Niels L.

doi:10.3181/00379727-94-22880

Cited by 59 publications

(12 citation statements)

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“…In addition, the patients with drug-induced impairment of phenylalanine metabolism did not excrete phenylpyruvic acid in the urine. This is consistent with the finding of Armstrong and Low, who failed to detect phenylpyruvic acid in the urine unless the serum phenylalanine level exceeded 0.91 Mmoles per ml (19).…”

Section: Discussionsupporting

confidence: 81%

Phenylalanine Metabolism and Folic Acid Antagonists*

Goodfriend¹,

Kaufman²

1961

J. Clin. Invest.

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Section: Discussionsupporting

confidence: 81%

Phenylalanine Metabolism and Folic Acid Antagonists*

Goodfriend¹,

Kaufman²

1961

J. Clin. Invest.

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“…In one case the apparent transamination defect did not persist past the age of nine months. The possibility of substantial variation of transaminase activity among PKU patients is suggested by the data of Armstrong and Low [6], who found that phenyl-…”

Section: Discussionmentioning

confidence: 99%

“…Blood phenylalanine concentrations greater than 15mg/dl are associated with significant aromatic aciduria after the neonatal period [6]. Indeed, the magnitude of aromatic acid excretion following an oral phenylalanine load is of diagnostic import in distinguishing between classic PKU and hyperphenylalaninemic variants [7] as well as PKU heterozygotes [8].…”

Section: Discussionmentioning

confidence: 99%

Absent phenylalanine hydroxylase activity without phenylketonuria

Segal

1980

Eur J Pediatr

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A male infant is described who never manifested phenylketonuria even though phenylalanine hydroxylase activity was undetectable in liver tissue. Plasma phenylalanine were elevated in the range typical of PKU patients when the baby was at breast and declined with institution of a low phenylalanine diet. Physical and psychomotor development were normal with the baby on the latter treatment. The results indicate that the absence of phenylketonuria does not rule out phenylalanine hydroxylase activity.

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“…Isolated phenylalanine transaminase deficiencies were also postulated by Auerbach in 1965 [7], and several observations were later attributed to age, 2, 10, a n d 40 times higher a t 6 m o n t h s , 1 year, and 2 years, respectively, t h a n before 2 m o n t h s of age; (4) t h a t t h e excretion thresholds of 0.4-0.5 p m o l / m l (7 t o 8 m g ) f o r o-OH-PAA [3, 9, 111 a n d of 0.6-0.9 pmol/ml (10-15 m g / 1 0 0 m l ) f o r PPA [6,91 are r e a c h e d only after t h e a g e of 2 years. T h i s e x p l a i n s why, a t t h e first e x a m i n a t i o n , t h e patients w i t h p h e n y l a l a n i n e m i a beiow 1.5 p m o l / m l c a n be considered as affected by a t r a n s a m i n a t i o n defect a n d w h y those presenting h i g h e r p l a s m a levels a n d excreting e n o u g h PPA t o show a positive ferric c h l o r i d e test a r e considered immediately t o be deficient in p h e n y l a l a n i n e hydroxylase.…”

Section: Discussionmentioning

confidence: 99%

“…These metabolites are, of course, normally found in urine with levels of phenylalanine in plasma greater than 0.4 pmol/ml (7 mg/100 ml) for the former and 0.9 pmol/ ml (15 mg/100 ml) for the latter, their catabolism being, below these values, faster than their synthesis [3,6,161. However, the influence of age on their excretion has as yet never been analyzed systematically in children under 2 years of age.…”

Section: Introductionmentioning

confidence: 99%

Influence of Age on ortho-Hydroxyphenylacetic Acid Excretion in Phenylketonuria and Its Genetic Variants

et al. 1974

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ExtractExcretion in urine of o-hydroxyphenylacetic acid (0-OH-PAA) was measured quantitatively during a 24-hr period in 43 children ranging from 2 weeks to 12 years of age who were affected by different types of hyperphenylalaninemia (20 typical phenylketonuria (PKU) 7 atypical PKU, and 16 mild forms according to the classification of Auerbach et 01.); 28 out of the 33 cases diagnosed at birth in the course of a screening program were examined before reaching 3 months of age. Phenylpyruvic acid (PPA) excretion was estimated at the same time semiquantitatively.I t was found ( I ) that ferric chloride tests were negative constantly and the daily excretion of o-OH-PAA was always inferior to 5 p~/ 2 4 hr in the younger group when the level of phenylalanine in plasma was below 1.5 pmol/ml; (2) that o-OH-PAA excretion increased significantly as the children got older : 1 1.0 f 3.8 before 3 months, 16.1 f 15.9 at 6 months, 75.0 f 48.5 at 1 year, and 122.1 i 84.7 p~/ 2 4 hr at 2 years of age for levels of phenylalanine in plasma which ranged from 1.5 to 2.1 pmol/ ml; (3) that the excretion thresholds for o-OH-PAA and PPA reached adult values (0.4-0.5 and 0.7-0.9 pmol/ml, respectively) only after 2 years.In 16 cases, using intravenous perfusion of 0.06 M L-phenylalanine, we have shown also that the PPA and o-OH-PAA excretion was identical whatever the type of (PKU) or mild forms) insofar as the levels of phenylalanine in plasma reached (1.5-3.0 pmol/ml) were equal in both types. Speculation This paper presents observations which demonstrate that only a minute amount of o-OH-PAA is excreted daily in the urine of both classic PKU and other forms of hyperphenylalaninemia during the first months of life. I t is suggested that this very low excretion is caused by a delayed maturation of phenylalanine transaminase; it is further proposed that the different types of hyperphenylalaninemia, with the exception of those caused by a deficiency of the tyrosine-oxidizing system, are all secondary to mutations affecting the phenylalanine hydrox>lase system.

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Phenylketonuria VIII. Relation between Age, Serum Phenylalanine Level, and Phenylpyruvic Acid Excretion.

Cited by 59 publications

References 0 publications

Phenylalanine Metabolism and Folic Acid Antagonists*

Phenylalanine Metabolism and Folic Acid Antagonists*

Absent phenylalanine hydroxylase activity without phenylketonuria

Influence of Age on ortho-Hydroxyphenylacetic Acid Excretion in Phenylketonuria and Its Genetic Variants

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