Validation of the Phenylalanine/Tyrosine Ratio Determined by Tandem Mass Spectrometry: Sensitive Newborn Screening for Phenylketonuria

Ceglarek, Uta; Müller, Peter E.; Stach, Barbara; Bührdel, P; Thiery, Joachim; Kieß, Wieland

doi:10.1515/cclm.2002.119

Cited by 63 publications

(48 citation statements)

References 10 publications

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“…Twice a week, they mailed the filter paper cards to the hospital. Analysis of phe and tyrosine was performed by liquid chromatography/tandem mass spectrometry (LC-MS/MS) as previously described (Ceglarek et al, 2002).…”

Section: Methodsmentioning

confidence: 99%

Unrestricted consumption of fruits and vegetables in phenylketonuria: no major impact on metabolic control

Rohde¹,

Mütze²,

Weigel³

et al. 2012

Eur J Clin Nutr

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Background/Objectives: The treatment of phenylketonuria (PKU) requires consistent restriction of protein intake from natural sources. Therefore, protein from all foods has to be accounted for, even the small amounts in fruits and vegetables. We studied whether free consumption of fruits and vegetables containing less than 75 mg phenylalanine (phe) per 100 g affects metabolic control in children with PKU. Subjects/Methods: Fourteen children (2-10 years) were included in a cross-over study, with a two-week period of conventional treatment (accounting for protein from fruits and vegetables) and a two-week period with free fruit and vegetable consumption. The instruction to follow liberal fruit and vegetable consumption in the first or second study period was randomized. Detailed daily dietary records were obtained throughout the study. Phe and nutrient content was calculated. Dried-blood phe concentration was monitored daily. Results: Although total phe intake increased by an average of 58 mg per day (P ¼ 0.037) during the 2 weeks of free fruit and vegetable consumption, dried-blood phe concentrations were unchanged. Total intake of fruits and vegetables did not increase, but patients instead used the higher phe tolerance to consume more of other foods, which were calculated and accounted for. Conclusion: Free consumption of fruits and vegetables does not impair metabolic control in PKU patients over a 2-week period.

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Section: Methodsmentioning

confidence: 99%

Unrestricted consumption of fruits and vegetables in phenylketonuria: no major impact on metabolic control

Rohde¹,

Mütze²,

Weigel³

et al. 2012

Eur J Clin Nutr

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“…All parents were familiar with the proper technique, having been trained during the patients`newborn period. Phe and Tyr concentrations in dried blood were determined by liquid chromatography/ tandem mass spectrometry (LC-MS/MS) as previously described (Ceglarek et al 2002).…”

Section: Assessment Of Plasma Phe Concentrationsmentioning

confidence: 99%

Nutritional Changes and Micronutrient Supply in Patients with Phenylketonuria Under Therapy with Tetrahydrobiopterin (BH4)

et al. 2012

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Background: Since 2008 patients with BH 4 -sensitive phenylketonuria can be treated with sapropterin dihydrochloride (Kuvan®) in addition to the classic phenylalanine (Phe) restricted diet. The aim of this study was to evaluate the nutritional changes and micronutrient supply in patients with phenylketonuria (PKU) under therapy with tetrahydrobiopterin (BH 4 ).Subjects and Methods: 19 children with PKU (4-18 years) and potential BH 4 -sensitivity were included, 14 completed the study protocol. Dried blood Phe concentrations as well as detailed dietary records were obtained throughout the study at preassigned study days.Results: Eight patients could increase their Phe tolerance from 629 AE 476 mg to 2131 AE 1084 mg (P ¼ 0.006) under BH 4 while maintaining good metabolic control (Phe concentration in dried blood 283 AE 145 mM vs. 304 AE 136 mM, P ¼ 1.0), therefore proving to be BH 4 -sensitive. They decreased their consumption of special low protein products and fruit while increasing their consumption of high protein foods such as processed meat, milk and dairy products. Intake of vitamin D (P ¼ 0.016), iron (P ¼ 0.002), calcium (P ¼ 0.017), iodine (P ¼ 0.005) and zinc (P ¼ 0.046) significantly declined during BH 4 treatment while no differences in energy and macronutrient supply occurred.Conclusion: BH 4 -sensitive patients showed good metabolic control under markedly increased Phe consumption. However, the insufficient supply of some micronutrients needs consideration. Long-term multicenter settings with higher sample sizes are necessary to investigate the changes of nutrient intake under BH 4 therapy to further evaluate potential risks of malnutrition. Supplementation may become necessary.

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“…In 1997, Rashed et al (8) described a multi-method for the quantification of amino acids and acylcarnitines in dried blood spot samples of newborns. The method employs simple loop injection without chromatography and allows the analysis of up to 1000 samples with a single instrument per day (9). Using this approach the early diagnosis of a large number of inborn metabolic diseases has become possible that are missed by the current conventional screening merely for phenylketonuria.…”

Section: Neonatal Screeningmentioning

confidence: 99%

Liquid Chromatography-Tandem Mass Spectrometry – Application in the Clinical Laboratory

Vogeser¹

2003

Clinical Chemistry and Laboratory Medicine

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This review provides a concise survey of liquid chromatography-tandem mass spectrometry (LC-TMS) as an emerging technology in clinical chemistry. The combination of two mass spectrometers with an interposed collision cell characterizes LC-TMS as an analytical technology on its own and not just as a more specific detector for HPLC compared with conventional techniques. In LC-TMS, liquid chromatography is rather used for sample preparation but not for complete resolution of compounds of interest. The instrument technology of LC-TMS is complex and comparatively expensive; however, in routine use, methods are far more rugged compared to conventional chromatographic techniques and enable high-throughput analyses with very limited manual handling steps. Moreover, compared to both gas chromatography-mass spectrometry (GC-MS) and conventional HPLC techniques, LC-TMS is substantially more versatile with respect to the spectrum of analyzable compounds. For these reasons it is likely that LC-TMS will gain far more widespread use in the clinical laboratory than HPLC and GC-MS ever did. In this article, the key features of LC-TMS are described, method development is explained, typical fields of application are discussed, and personal experiences are related. Clin Chem Lab Med 2003; 41(2):117 -126

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Validation of the Phenylalanine/Tyrosine Ratio Determined by Tandem Mass Spectrometry: Sensitive Newborn Screening for Phenylketonuria

Cited by 63 publications

References 10 publications

Unrestricted consumption of fruits and vegetables in phenylketonuria: no major impact on metabolic control

Unrestricted consumption of fruits and vegetables in phenylketonuria: no major impact on metabolic control

Nutritional Changes and Micronutrient Supply in Patients with Phenylketonuria Under Therapy with Tetrahydrobiopterin (BH4)

Liquid Chromatography-Tandem Mass Spectrometry – Application in the Clinical Laboratory

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