Published: Januari 2017 in JIMD Reports
Article: Daily variation of blood phenylalanine and tyrosine in Tyrosinemia type 1 patients without extra phenylalanine
Authors: E van Dam, G Venema-Liefaard, M van Rijn, A MacDonald, MR Heiner-Fokkema, FJ van Spronsen
Contact: Esther van Dam
Link to article: ncbi.nlm.nih.gov
Nowadays, most patients perform fingerstick bloodspots at home. Usually we ask patients to do this in the morning. We did not know if there was some variation in phenylalanine and tyrosine concentrations during the day. This was done based on experience with other metabolic disease in which phenylalanine and tyrosine play a role.
We wanted to know if it was best to measure phenylalanine and tyrosine in the morning? To answer this question, patients from Groningen and Birmingham were asked to participate. This project was financed and made possible by the Tyrosinemia Foundation (previously known as Stichting Joris). Patients were asked to take four bloodspots during three consecutive days. After analyses it turned out that especially phenylalanine concentrations tend to vary during the day.
Phenylalanine concentrations were much lower in the afternoon when compared to the morning. However, there is less variation during the morning compared to the afternoon. Therefore we advised patients to take bloodspots in the morning, while taking the afternoon drop of phenylalanine into account. When a patient shows low phenylalanine concentrations in the morning, it is likely that concentrations are even lower in the afternoon.