title: Kidney Disease in Adenine Phosphoribosyltransferase Deficiency.
abstract: BACKGROUND
  Adenine phosphoribosyltransferase (APRT) deficiency is a purine metabolism disorder causing kidney stones and chronic kidney disease (CKD). The course of nephrolithiasis and CKD has not been well characterized. The objective of this study was to examine long-term kidney outcomes in patients with APRT deficiency.
  
  
  METHODS
  An observational cohort study.
  
  
  METHODS
  All patients enrolled in the APRT Deficiency Registry of the Rare Kidney Stone Consortium.
  
  
  RESULTS
  Kidney stones, acute kidney injury (AKI), stage of CKD, end-stage renal disease, estimated glomerular filtration rate (eGFR), and changes in eGFR.
  
  
  METHODS
  Serum creatinine and eGFR calculated using creatinine-based equations.
  
  
  RESULTS
  Of 53 patients, 30 (57%) were females and median age at diagnosis was 37.0 (range, 0.6-67.9) years. Median duration of follow-up was 10.3 (range, 0.0-31.5) years. At diagnosis, kidney stones had developed in 29 (55%) patients and 20 (38%) had CKD stages 3 to 5, including 11 (21%) patients with stage 5. At latest follow-up, 33 (62%) patients had experienced kidney stones; 18 (34%), AKI; and 22 (42%), CKD stages 3 to 5. Of 14 (26%) patients with stage 5 CKD, 12 had initiated renal replacement therapy. Kidney stones recurred in 18 of 33 (55%) patients. The median eGFR slope was -0.38 (range, -21.99 to 1.42) mL/min/1.73m(2) per year in patients receiving treatment with an xanthine dehydrogenase inhibitor and -5.74 (range, -75.8 to -0.10) mL/min/1.73m(2) per year in those not treated prior to the development of stage 5 CKD (P=0.001).
  
  
  CONCLUSIONS
  Use of observational registry data.
  
  
  CONCLUSIONS
  Progressive CKD and AKI episodes are major features of APRT deficiency, whereas nephrolithiasis is the most common presentation. Advanced CKD without a history of kidney stones is more prevalent than previously reported. Our data suggest that timely therapy may retard CKD progression.
authors.affiliation: Faculty of Medicine, School of Health Sciences, University of Iceland, Reykjavik, Iceland.
authors.forename: Hrafnhildur Linnet
authors.initials: HL
authors.lastname: Runolfsdottir
authors.affiliation: Faculty of Medicine, School of Health Sciences, University of Iceland, Reykjavik, Iceland; Division of Nephrology, Internal Medicine Services, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland.
authors.forename: Runolfur
authors.initials: R
authors.lastname: Palsson
authors.affiliation: Children's Medical Center, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland.
authors.forename: Inger M
authors.initials: IM
authors.lastname: Agustsdottir
authors.affiliation: Division of Nephrology, Internal Medicine Services, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland.
authors.forename: Olafur S
authors.initials: OS
authors.lastname: Indridason
authors.affiliation: Faculty of Medicine, School of Health Sciences, University of Iceland, Reykjavik, Iceland; Children's Medical Center, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland. Electronic address: vidare@lsh.is.
authors.forename: Vidar O
authors.initials: VO
authors.lastname: Edvardsson
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D000228:Adenine Phosphoribosyltransferase / Q000172:deficiency* / Q000378:metabolism; D000328:Adult; D018450:Disease Progression; D061345:Early Medical Intervention / Q000379:methods / Q000706:statistics & numerical data; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D007055:Iceland / Q000453:epidemiology; D007668:Kidney / Q000378:metabolism / Q000503:physiopathology; D007669:Kidney Calculi / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D007676:Kidney Failure, Chronic / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D007677:Kidney Function Tests; D008297:Male; D008661:Metabolism, Inborn Errors / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology / Q000378:metabolism; D015995:Prevalence; D017582:Renal Replacement Therapy / Q000379:methods / Q000706:statistics & numerical data; D052878:Urolithiasis / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology / Q000378:metabolism
chemical_list: D000228:Adenine Phosphoribosyltransferase
keywords: End-stage renal disease; acute kidney injury (AKI); adenine phosphoribosyltransferase (APRT) deficiency; chronic kidney disease (CKD); crystal nephropathy; disease progression; estimated glomerular filtration rate (eGFR); kidney failure; kidney stone; nephrolithiasis; purine metabolism disorder; renal function; renal replacement therapy (RRT)