title: INCREASED SERUM LEVELS OF UREA AND CREATININE ARE SURROGATE MARKERS FOR DISRUPTION OF RETINAL PHOTORECEPTOR EXTERNAL LIMITING MEMBRANE AND INNER SEGMENT ELLIPSOID ZONE IN TYPE 2 DIABETES MELLITUS.
abstract: OBJECTIVE
  To evaluate the role of serum urea and creatinine as surrogate markers for disruption of retinal photoreceptor external limiting membrane (ELM) and inner segment ellipsoid zone (EZ) in Type 2 diabetic retinopathy (DR) using spectral-domain optical coherence tomography, for the first time.
  
  
  METHODS
  One hundred and seventeen consecutive cases of Type 2 diabetes mellitus (diabetes without retinopathy [No DR; n = 39], nonproliferative diabetic retinopathy [NPDR; n = 39], proliferative diabetic retinopathy [PDR; n = 39]) and 40 healthy control subjects were included. Serum levels of urea and creatinine were assessed using standard protocol. Spectral-domain optical coherence tomography was used to grade the disruption of ELM and EZ as follows: Grade 0, no disruption of ELM and EZ; Grade 1, ELM disrupted, EZ intact; Grade 2, ELM and EZ disrupted. Data were analyzed statistically.
  
  
  RESULTS
  Increase in serum levels of urea (F = 22.93) and creatinine (F = 15.82) and increased grades of disruption of ELM and EZ (γ = 116.3) were observed with increased severity of DR (P < 0.001). Increase in serum levels of urea (F = 10.45) and creatinine (F = 6.89) was observed with increased grades of disruption of ELM and EZ (P = 0.001).
  
  
  CONCLUSIONS
  Serum levels of urea and creatinine are surrogate markers for disruption of retinal photoreceptor ELM and EZ on spectral-domain optical coherence tomography in DR.
authors.affiliation: *Retina Service, Department of Ophthalmology, King George's Medical University, Lucknow, India;Departments of †Social and Preventive Medicine, and‡Pathology, King George's Medical University, Lucknow, India;§Department of Ophthalmology, Pallas Klinik, Olten, Switzerland;¶Department of Ophthalmology, University of Adelaide, Adelaide, South Australia, Australia;**Department of Cardiovascular Diseases, International Clinical Research Center, St. Anne's University Hospital and Masaryk University, Brno, Czech Republic; and††Department of Ophthalmology, Saint Louis University Eye Institute, Saint Louis University, St. Louis, Missouri.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Saxena
authors.forename: Surabhi
authors.initials: S
authors.lastname: Ruia
authors.forename: Senthamizh
authors.initials: S
authors.lastname: Prasad
authors.forename: Astha
authors.initials: A
authors.lastname: Jain
authors.forename: Nibha
authors.initials: N
authors.lastname: Mishra
authors.forename: Shankar M
authors.initials: SM
authors.lastname: Natu
authors.forename: Carsten H
authors.initials: CH
authors.lastname: Meyer
authors.forename: Jagjit S
authors.initials: JS
authors.lastname: Gilhotra
authors.forename: Peter
authors.initials: P
authors.lastname: Kruzliak
authors.forename: Levent
authors.initials: L
authors.lastname: Akduman
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D015415:Biomarkers / Q000097:blood; D016022:Case-Control Studies; D003404:Creatinine / Q000097:blood*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000473:pathology*; D003930:Diabetic Retinopathy / Q000097:blood* / Q000473:pathology* / Q000503:physiopathology; D019773:Epiretinal Membrane / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020419:Photoreceptor Cells, Vertebrate / Q000473:pathology; D012164:Retinal Diseases; D055211:Retinal Photoreceptor Cell Inner Segment / Q000473:pathology*; D012720:Severity of Illness Index; D014508:Urea / Q000097:blood*
chemical_list: D015415:Biomarkers; D014508:Urea; D003404:Creatinine