title: Urine Beta2-Microglobulin Is an Early Marker of Renal Involvement in LPI.
abstract: OBJECTIVE
  Lysinuric protein intolerance (LPI) is a rare autosomal recessive disorder affecting the transport of cationic amino acids. It has previously been shown that approximately one third of the Finnish LPI patients have impaired renal function. The aim of this study was to analyse in detail urine beta2-microglobulin values, renal dysfunction, oral L-citrulline doses and plasma citrulline concentrations in Finnish LPI patients.
  
  
  RESULTS
  Of the 41 Finnish LPI patients, 56% had proteinuria and 53% hematuria. Mean plasma creatinine concentration was elevated in 48%, serum cystatin C in 62%, and urine beta2-microglobulin in 90% of the patients. Seventeen per cent of the patients developed ESRD, and five of them received a kidney transplant. L-citrulline doses and fasting plasma citrulline concentrations were similar in adult LPI patients with decreased and normal GFR (mean ± SD 79.5 ± 29.2 vs. 82.4 ± 21.9 mg/kg/day, P = 0.619, and 80.3 ± 20.1 vs. 64.8 ± 23.0 μmol/l, P = 0.362, respectively).
  
  
  CONCLUSIONS
  Urine beta2-microglobulin is a sensitive early marker of renal involvement, and it should be monitored regularly in LPI patients. Weight-based oral L-citrulline doses and plasma citrulline concentrations were not associated with renal function. LPI patients with ESRD were successfully treated with dialysis and kidney transplantation.
authors.affiliation: Department of Pediatrics, University of Turku, Turku, Finland. maseka@utu.fi.
authors.forename: Mari
authors.initials: M
authors.lastname: Kärki
authors.affiliation: Department of Pediatrics, University of Turku, Turku, Finland.
authors.forename: Kirsti
authors.initials: K
authors.lastname: Näntö-Salonen
authors.affiliation: Department of Pediatrics and Physiology, University of Turku, Turku, Finland.
authors.forename: Harri
authors.initials: H
authors.lastname: Niinikoski
authors.affiliation: Department of Medical Biochemistry and Genetics, University of Turku, Turku, Finland.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Tanner