title: Risk factors for calculus formation in patients with renal transplants.
abstract: OBJECTIVE
  To investigate the risk factors for stone formation in patients with functioning renal transplants in whom renal calculi develop.
  
  
  METHODS
  Renal calculi developed in six of 178 patients with functioning renal transplants under current review, an incidence of 3%. Risk factors for stone formation were investigated in five of these patients and compared with a randomly selected control group of 41 transplant patients with no stone problems.
  
  
  RESULTS
  Patients with transplant calculi typically passed smaller volumes of significantly more concentrated and alkaline urine with greater urinary excretion of uric acid (P < 0.05). Urine calcium excretion was also increased. Crystalluria was present in three of five stone formers compared with two of 25 controls. Overall, metabolic abnormalities included hypocitraturia (75%), hyperparathyroidism (36%), hypophosphataemia (24%) and hypercalcaemia (10%). Urinary infection was common (50%) and urinary output of magnesium and phosphate was at the lower end of normal for all patients.
  
  
  CONCLUSIONS
  These results suggest a multifactorial aetiology for stone formation in renal transplant recipients. Approaches to prevention and management are discussed.
authors.affiliation: St Peter's Hospital, Department of Nephrology, London, UK.
authors.forename: J M
authors.initials: JM
authors.lastname: Harper
authors.forename: C T
authors.initials: CT
authors.lastname: Samuell
authors.forename: P C
authors.initials: PC
authors.lastname: Hallson
authors.forename: S M
authors.initials: SM
authors.lastname: Wood
authors.forename: M A
authors.initials: MA
authors.lastname: Mansell
mesh_terms: D002951:Citrates / Q000652:urine; D003460:Crystallization; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007669:Kidney Calculi / Q000209:etiology* / Q000652:urine; D016030:Kidney Transplantation; D008297:Male; D011183:Postoperative Complications; D012307:Risk Factors; D014552:Urinary Tract Infections / Q000209:etiology; D014554:Urination
chemical_list: D002951:Citrates