title: Creatinine measurement on dry blood spot sample for chronic kidney disease screening.
abstract: BACKGROUND
  Chronic kidney disease (CKD) screening is advisable due to its high morbidity and mortality and is usually performed by sampling blood and urine.
  
  
  OBJECTIVE
  Here we present an innovative and simpler method, by measuring creatinine on a dry blood spot on filter paper.
  
  
  METHODS
  One-hundred and six individuals at high risk for CKD were enrolled. The creatinine values obtained using both tests and the demographic data of each participant allowed us to determinate the eGFR. The adopted cutoff for CKD was an eGFR < 60 ml/min.
  
  
  RESULTS
  Mean age was 57 ± 12 years, 74% were female, 40% white, and 60% non-white. Seventy-six percent were hypertensive, 30% diabetic, 37% had family history of CKD, and 22% of smoking. The BMI was 29.5 ± 6.9 kg/m2, median systolic blood pressure was 125 mmHg (IQR 120-140 mmHg) and median diastolic blood pressure was 80 mmHg (IQR 70-80 mmHg). According to MDRD equation, sensitivity was 96%, specificity 55%, predictive positive value 96%, predictive negative value 55% and accuracy 92%. By the CKD-EPI equation the sensitivity was 94%, specificity 55%, predictive positive value 94%, predictive negative value 55% and accuracy 90%. A Bland and Altman analysis showed a relatively narrow range of creatinine values differences (+ 0.68mg/dl to -0.55mg/dl) inside the ± 1.96 SD, without systematic differences.
  
  
  CONCLUSIONS
  Measurement of creatinine on dry blood sample is an easily feasible non-invasive diagnostic test with good accuracy that may be useful to screen chronic kidney disease.
authors.affiliation: Universidade Federal Fluminense, Brazil.
authors.forename: Alan Castro Azevedo E
authors.initials: AC
authors.lastname: Silva
authors.affiliation: Instituto Vital Brazil, Brazil.
authors.forename: Juan Fidel Bencomo
authors.initials: JF
authors.lastname: Gómez
authors.affiliation: Universidade Federal Fluminense, Brazil.
authors.forename: Jocemir Ronaldo
authors.initials: JR
authors.lastname: Lugon
authors.affiliation: Universidade Federal Fluminense, Brazil.
authors.forename: Miguel Luis
authors.initials: ML
authors.lastname: Graciano
mesh_terms: D000368:Aged; D003404:Creatinine / Q000097:blood*; D059788:Dried Blood Spot Testing; D005260:Female; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis*
chemical_list: D003404:Creatinine