In phenylketonuria (PKU) toxic phenylalanine (Phe) can harm other organs beyond the
brain. Furthermore, the lifelong therapy of PKU consists of consumption of increased
amounts of amino acid mixture that provoke hyperfiltration in glomeruli. Therefore,
the adherence to therapy in PKU might influence the long-term kidney function in PKU
patients.Data from 41 adult, early treated PKU patients were analyzed in this 10-year,
retrospective, monocentric study. Two subgroups were created according to their therapy-adherence:
one with long-term blood Phe levels in the therapeutic range (<600 µmol/l), and one
with suboptimal blood Phe levels. Renal function and metabolic parameters were collected
over 10 years. Kidney function parameters were compared between the two groups and
associations between blood Phe levels and kidney function were tested.After 10 years,
serum creatinine levels (p=0,369) and estimated glomerular filtration rate (eGFR)
(p=0,723) did not change significantly from baseline in the good therapeutic group.
The suboptimal therapeutic group's eGFR decreased in the same period (from 110.4 ±
14 ml/min/1,73 m2 to 94.2 ± 16 ml/min/1.73 m2, p=0.017). At 10 years the suboptimal
therapeutic group had an increased serum creatinine level (81 ± 14.4 μmol/L vs. 71.5
± 13 μmol/L vs., p=0.038), and a decreased eGFR (94.2 ± 16 ml/min/1.73 m2 vs. 103.3
± 13 ml/min/1.73 m2 p=0.031) compared to the good adhering group. Significant negative
correlation between Phe levels and eGFR (r=-0.41, p=0.008) was observed.Long-term
suboptimal therapy adherence in PKU patients with high blood Phe levels may lead to
deteriorations in kidney function.
