PMID: 3766433Oct 1, 1986Paper

Impaired phenylalanine-tyrosine conversion in patients with iron-deficiency anemia studied by a L-(2H5)phenylalanine-loading test

The American Journal of Clinical Nutrition
W D Lehmann, H C Heinrich

Abstract

Ten patients with manifest iron deficiency and without documented relationship to phenylketonuria patients were orally loaded with 25 mg/kg of L-(2H5)phenylalanine. Before loading, the fasting phenylalanine-tyrosine plasma ratio was determined and after loading, the concentrations of labeled and nonlabeled phenylalanine and tyrosine were determined in five consecutive plasma samples. With respect to the fasting phenylalanine-tyrosine ratio and to the post-load ratios of labeled phenylalanine over labeled tyrosine, the iron-deficient patients showed data intermediate between those of normals and heterozygotes for phenylketonuria. Compared to a 100% in vivo activity of phenylalanine hydroxylase in normals and a circa 37% activity in heterozygotes for classic phenylketonuria, iron-deficient patients with an average hemoglobin of 8.6 +/- 1 g/dl showed an activity of circa 56%. After normalization of their iron status, four patients were subjected again to the L-(2H5)phenylalanine-loading test. For three of these individuals, test results shifted into the range of normal.

Citations

Oct 1, 1993·Journal of the American College of Nutrition·B D Miranda da CruzK Widhalm
Mar 27, 2007·The British Journal of Nutrition·Colin A McKenzieShosuke Ito
Oct 24, 2018·Pharmaceuticals·Marco T Nuñez, Pedro Chana-Cuevas
Jun 1, 1989·The Journal of Pediatrics·W D Lehmann

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