title: Chronic kidney disease in adolescent and adult patients with phenylketonuria.
abstract: OBJECTIVE
  A lifelong phenylalanine-restricted diet with supplementation of a phenylalanine-free amino acid formula is recommended in patients with phenylketonuria (PKU). The effect of a long-term PKU diet on renal function and blood pressure has not been investigated yet.
  
  
  METHODS
  We analyzed renal function in 67 patients with PKU, aged 15-43 years, by measuring glomerular filtration rate (GFR) and effective renal plasma flow by isotope clearance ((51)Cr-EDTA, (123)J-Hippuran), estimated GFR, blood retention parameters, urinary protein and electrolyte excretion. Renal ultrasound and 24 h ambulatory blood pressure monitoring were performed additionally. Patients were divided into three groups according to their: 1) current diet (CD), i.e., daily protein intake: ICD <0.8 g/kg, IICD 0.8-1.04 g/kg, IIICD >1.04 g/kg; 2) life-long diet time (LDT), i.e., cumulative years of life in which daily protein intake exceeded dietary recommendations: ILDT <15 years, IILDT 15-19 years, IIILDT >19 years.
  
  
  RESULTS
  GFR was decreased in 19 % of the patients. With increasing protein intake, GFR decreased significantly (ICD 111 ml/min; IICD 105 ml/min; IIICD 99 ml/min. ILDT 112 ml/min; IILDT 103 ml/min; IIILDT 99 ml/min). Proteinuria was detected in 31 %, microalbuminuria in 7 %, and hypercalciuria in 23 % of the patients. 23 % of the patients had arterial hypertension, and 41 % revealed a nocturnal non-dipping status.
  
  
  CONCLUSIONS
  In patients with PKU on a lifelong diet we could detect impaired renal function in 19 %, proteinuria in 31 %, and arterial hypertension in 23 %. Thus, chronic kidney disease may develop in PKU patients, and routine renal function tests should be performed during long-term follow-up.
authors.affiliation: Department of Pediatric Endocrinology, Gastroenterology and Metabolic Diseases, Charité Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany. julia.hennermann@charite.de
authors.forename: Julia B
authors.initials: JB
authors.lastname: Hennermann
authors.forename: Sylvia
authors.initials: S
authors.lastname: Roloff
authors.forename: Jutta
authors.initials: J
authors.lastname: Gellermann
authors.forename: Ilka
authors.initials: I
authors.lastname: Vollmer
authors.forename: Elke
authors.initials: E
authors.lastname: Windt
authors.forename: Barbara
authors.initials: B
authors.lastname: Vetter
authors.forename: Ursula
authors.initials: U
authors.lastname: Plöckinger
authors.forename: Eberhard
authors.initials: E
authors.lastname: Mönch
authors.forename: Uwe
authors.initials: U
authors.lastname: Querfeld
mesh_terms: D000293:Adolescent; D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D003430:Cross-Sectional Studies; D018753:Diet, Protein-Restricted / Q000009:adverse effects; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D008297:Male; D010661:Phenylketonurias / Q000503:physiopathology* / Q000652:urine*; D011507:Proteinuria / Q000503:physiopathology / Q000652:urine; D012079:Renal Circulation / Q000502:physiology; D051437:Renal Insufficiency / Q000503:physiopathology / Q000652:urine; D051436:Renal Insufficiency, Chronic / Q000652:urine*; D055815:Young Adult