Long-term treatment for hyperphenylalaninemia and phenylketonuria: a risk for nutritional vitamin B12 deficiency?

Abstract

We have proven that adult patients with PKU and HPA are at risk of vitamin B12 nutritional deficiency. The most effective parameter for these adults is the monitoring of holotranscobalamin in the serum.

Prooxidant-antioxidant balance in patients with phenylketonuria and its correlation to biochemical and hematological parameters

“…Treatment for PKU patients is based on the prohibition of Phe absorption, through a protein-restricted diet and the avoidance of high-content Phe foods [9,10]. However, lack of protein intake may increase the risk of nutritional defect that may result in a low total antioxidant status that can establish oxidative stress especially after adolescence [11].…”

Functional vitamin B12 deficiency in phenylketonuria patients and healthy controls: An evaluation with combined indicator of vitamin B12 status as a biochemical index

“…11,14–16 There have been only three studies using MMA measurement; however, PKU patients were not compared with healthy controls. 6,12,13 In those studies including adults with PKU, there was no significant difference in MMA concentrations, but the patients with normal or low vitamin B12 concentrations had increased concentrations of MMA and/or Hcy 6,12,13 or decreased concentrations of HoloTC. 12,13 Although HoloTC is considered a relatively early biomarker of vitamin B12 deficiency, there is conflicting evidence for its diagnostic performance.…”

“…Whereas one of them showed no difference in HoloTC between the patients with vitamin B12 concentrations of over 200 pmol/L and those with vitamin B12 concentrations of below 200 pmol/L, 12 the other revealed that HoloTC remained in the reference values despite the presence of a difference. 13 These two studies were different in terms of measurement methods and the reference values used (>50 pmol/L and 19–119 pmol/L, respectively).…”

“…7–9 Vitamin B12 deficiency is mainly reported in adolescent and adult PKU patients who do not regularly take Phe-free amino acid supplements including vitamins. 3,6–13 It is known that compliance with the restricted diet treatment is better in childhood. 1 However, studies on children and adolescents with PKU have revealed conflicting findings about vitamin B12 deficiency and compliance with the diet.…”

Vitamin B 12 deficiency and phenylketonuria

“…Os autores sugeriram a introdução das dosagens desses nutrientes no protocolo de atendimento dos pacientes. 7 Conclusões semelhantes foram recentemente publicadas por Procháskova et al 8 em estudo desenvolvido com pacientes adultos.Robinson et al 9 , em coorte de 83 pacientes, encontraram níveis séricos de vitamina B12 abaixo do valor de referência em 12,1% dos casos. Entre esses, somente um apresentava volume corpuscular médio aumentado.…”