The beneficial effect of adherence to the therapeutic diet on the main protein-energy wasting and several other biomarkers in children with phenylketonuria

Abstract

Replacement of natural protein intake, low total antioxidant status (TAS) and DNA oxidation and high phenylalanine (Phe) blood levels are implicated with poorly controlled patients with PKU. In this study we aimed to investigate the effect of diet on the main Protein Energy Wasting (PEW) along with other metabolic parameters in patients with phenylketonuria (PKU). Twenty-four poorly controlled patients (group A) and thirty patients who strictly adhered to their diet (group B) as well as controls (n = 50) underwent laboratory tests: complete blood count, concentrations of ferritin, lipid, lipoprotein, TAS, as well as Phe levels with appropriate methodology. Phe levels differed significantly among the groups. Lipids lipoproteins, except HDL, were higher in group A than those measured in group B and controls. TG was not higher in any group. TAS (386 ? 30 vs 204 ? 23 ?mol/L, p < 0.001), ferritin (65 ? 12 vs 52 ? 10 ?g/L, p < 0.01) were significantly higher in group B. In contrast, White Blood Cell count (WBC) (6.1 ? 1.0 vs 8.3 ? 1.2 ? 103/?L, p < 0.01), the absolute number (1.9 ? 0.6 vs 2.9 ? 0.7 ? 103/?L, p < 0.001) and percentage of lymphocytes (18.5 ? 3.0 vs 39.3 ? 4.0%, p < 0.01) were lower in group A than those in group B, whereas total protein and albumin levels were similar among the groups. Most main PEW biomarkers, the low WBC, the low absolute and percentage of lymphocytes in poorly controlled patients may be directly and/or indirectly affected by their high Phe levels and/or low TAS levels in children with PKU on ?loose diet?.

Protein status in phenylketonuria: A scoping review

“…No associations between dietary protein intake and biochemical markers of protein status were reported across studies [42,62], although studies were limited. Moreover, whether participants consumed a vegan diet, vegan plus protein substitutes, unrestricted or PKU diets did not alter total protein levels [72].…”

“…There was greater variation in participant age for studies including biochemical measurements of protein status than anthropometric measurements of protein studies. Six studies were conducted in children (age range 13.7 days to 10 years) [33,38,42,84,85,89], ten studies were in children and adolescents (age range 2.4 monthse18 years) [44,56,62,69,74,76,77,83,86,90], 15 in adolescents and adults (11e49 years) [7,39,40,45,46,57,63,64,70,72,75,79,91e93] and two in adults only [41,82]. Seven studies included mixed-age cohorts (age range 7 monthse54 years) [26,36,37,80,81,94,95].…”

“…A range of biochemical measurements were used to assess protein status, and most studies included multiple measurement (Table 3). Serum albumin [36,41,42,56,62,63,69,72,74,78,85,86,95], prealbumin [26,34,37,57,80,81,84,87,89] or both [33,38,40,45,46,76,77,82,83,88,90,91,93,94] were the most common biochemical measurements reported. Total protein [36,40e42,56,63,72,76,78,80,81,85,86,91,93,94] and blood urine nitrogen (BUN) [33,40,45,74,75,78,85,86,93] were also frequently used.…”

“…The key findings for biochemical assessments of protein status are summarized in Table 5. In children with PKU, no differences in albumin [33,38,42], total protein [42], retinol binding protein [33], BUN [33] or plasma essential amino acid (EAA) concentrations (except phenylalanine) were reported compared to healthy controls [89]. In children and adolescents, studies reported albumin [56,62,83,85], total protein [56,83,85], creatinine [62], BUN [85] and/or plasma amino acid levels [44] were comparable to untreated HPA or controls.…”

“…Prealbumin levels were observed to correlate with haemoglobin levels [87]. Age was reported to positively correlate with serum total protein levels [81] and albumin concentrations [95], whereas findings for metabolic control were inconsistent [42,81].…”