The challenge of long-term tetrahydrobiopterin (BH4) therapy in phenylketonuria:
Effects on metabolic control, nutritional habits and nutrient supply
#MMPMID26937412
Thiele AG
; Rohde C
; Mütze U
; Arelin M
; Ceglarek U
; Thiery J
; Baerwald C
; Kiess W
; Beblo S
Mol Genet Metab Rep
2015[Sep]; 4
(?): 62-7
PMID26937412
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BACKGROUND AND AIMS: BH4-sensitive phenylketonuria (PKU) patients relax their
phenylalanine (Phe) restricted diet due to increased Phe tolerance, while keeping
dried blood Phe concentrations with in the therapeutic range. We aimed to
investigate metabolic control, eating habits and nutrient supply under long-term
BH4-therapy. PATIENTS AND METHODS: Retrospective analysis of mean dried blood Phe
concentrations and their variability, food and nutrient intake in BH4-sensitive
patients (n = 8, 3f, age 6.0-16.6 y) under classical dietary treatment for one
year and during the three years after initiation of BH4. RESULTS: Phe
concentrations of BH4-sensitve PKU patients remained within therapeutic range
throughout the observation period, independent of therapeutic regime. Under BH4,
Phe tolerance increased significantly (493.2 ± 161.8 mg/d under classical diet vs
2021.93 ± 897.4 mg/d two years under BH4; P = 0.004). Variability of Phe
concentrations remained unchanged (mean SD; P = 1.000). Patients adjust their
food choice and significantly increased their intake of cereals, potatoes, dairy
products and meat (P = 0.019, P = 0.016, P = 0.016 and P = 0.016, respectively).
Under diet changes after implementation of BH4 a drop in micronutrient intake
(vitamin D, folic acid, iron, calcium, iodine) could be revealed (P = 0.005,
P < 0.001, P = 0.004, P = 0.001, P = 0.003, respectively). CONCLUSIONS:
BH4-sensitive PKU patients can achieve good metabolic control under an adjuvant
BH4- or a BH4 monotherapy. The liberalized diet under BH4 seems to jeopardize the
quality of patients' nutrition, and these patients require close follow-up and
special nutrition education to minimize the risk for imbalanced diet and nutrient
deficiencies.