title: Urinary Clara Cell Protein in Kidney Transplant Patients: A Preliminary Study.
abstract: OBJECTIVE
  The aim of this exploratory study was to analyze the urinary excretion of Clara cell protein (CC16), a new marker of proximal tubular dysfunction (PTD), in kidney transplantation (KT).
  
  
  METHODS
  Urinary concentrations of CC16, β2-microglobulin (β2m), and N-acetyl-glucosaminidase (NAG) were measured in 50 KT patients (72% men; mean age 50.4 ± 12.4 years; diabetes in 24%; duration of KT 4.3 ± 3.1 years) and 10 healthy controls (6 men; mean age 33.6 ± 13.4 years).
  
  
  RESULTS
  Urinary levels of β2m, NAG, and CC16 were significantly higher in KT patients than in controls: β2m: 0.77 (interquartile range [IQ] 0.22 to 4.62) g/g vs 0.069 (IQ 0.05 to 0.10) g/g; NAG: 3.16 (IQ 2.09 to 5.33) U/g vs 1.73 (IQ 1.25 to 2.07) U/g; CC16: 26.01 (IQ 8.62 to 123.3) g/g vs 2.51 (IQ 0.83 to 7.18) g/g (P < .001). Elevated levels of β2m, NAG, and CC16 were found in 81%, 28%, and 71% of KT patients, respectively. Urinary levels of β2m, NAG, and CC16 significantly increase as glomerular filtration rate (GFR) decreases. Interestingly, in patients with GFR >60 mL/min, we still found high levels of β2m, NAG, and CC16 in 77%, 13%, and 52%, respectively. Diabetic subjects had significant higher levels of the 3 markers compared with nondiabetic subjects, without differences in albumin excretion or GFR. CC16 showed a positive correlation with urinary albumin (r = 0.42, P < .001), NAG (r = 0.352, P < .05), and β2m (r = 0.75, P < .001).
  
  
  CONCLUSIONS
  PTD is highly prevalent in KT patients. This is the first study that analyzes CC16 in KT patients, showing that the urinary excretion of this protein is significantly increased in this population. Further studies are needed to examine the clinical value of CC16 in KT patients.
authors.affiliation: Nephrology Service, University Hospital Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain. Electronic address: patri102@hotmail.com.
authors.forename: P M
authors.initials: PM
authors.lastname: García-García
authors.affiliation: Nephrology Service, University Hospital Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Martín-Izquierdo
authors.affiliation: Clinical Analysis Service, University Hospital Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.
authors.forename: C M-F
authors.initials: CM
authors.lastname: de Basoa
authors.affiliation: Nephrology Service, University Hospital Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Jarque-López
authors.affiliation: Nephrology Service, University Hospital Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.
authors.forename: G
authors.initials: G
authors.lastname: Pérez-Suárez
authors.affiliation: Nephrology Service, University Hospital Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Rivero-González
authors.affiliation: Nephrology Service, University Hospital Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: González-Posadas
authors.affiliation: Nephrology Service, University Hospital Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Macía-Heras
authors.affiliation: Pediatric Nephrology Unit, University Hospital Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.
authors.forename: V M
authors.initials: VM
authors.lastname: García-Nieto
authors.affiliation: Nephrology Service, University Hospital Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain; Research Unit, University Hospital Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain.
authors.forename: J F
authors.initials: JF
authors.lastname: Navarro-Gónzález
mesh_terms: D000118:Acetylglucosaminidase / Q000652:urine; D000328:Adult; D000419:Albuminuria / Q000652:urine; D015415:Biomarkers / Q000652:urine; D016022:Case-Control Studies; D003920:Diabetes Mellitus / Q000652:urine; D005198:Fanconi Syndrome / Q000209:etiology / Q000652:urine*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D016030:Kidney Transplantation / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000209:etiology / Q000652:urine*; D011184:Postoperative Period; D012307:Risk Factors; D014598:Uteroglobin / Q000652:urine*; D001613:beta 2-Microglobulin / Q000652:urine
chemical_list: D015415:Biomarkers; C556389:SCGB1A1 protein, human; D001613:beta 2-Microglobulin; D014598:Uteroglobin; D000118:Acetylglucosaminidase