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Do urinary levels of vascular endothelial growth factor predict proliferative retinopathy?
C T D'Angio1, J Ambati, D L Phelps
1Strong Children's Research Center, Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642, USA. carl_dangio@urmc.rochester.edu
Purpose:
Vascular endothelial growth factor (VEGF) is elevated in the vitreous of patients with proliferative retinopathies (PR). Angiogenic factors like VEGF are elevated in the urine of subjects with cancers, including those distant from the genitourinary tract. We hypothesized that local increases in VEGF in the vitreous would be reflected in the urine of subjects with PR.
Methods:
Urine samples were collected from adults with absent, mild, or severe (requiring laser photocoagulation) PR. VEGF was measured by enzyme linked immunosorbent assay.
Results:
Of 42 subjects, 16 had no PR and 26 had PR (8 mild, 18 severe). Thirty subjects had diabetes mellitus; 24 of these had PR. Subjects with PR were older than controls. Subjects with PR tended to have higher urinary VEGF (median 123 pg/ml Cr, range 3--1738) than controls without PR (median 93 pg/ml Cr, range 2--200) (p = 0.08). None of 16 controls, but 11/15 subjects with PR had >200 mg VEGF/mg Cr (p = 0.003), yielding high specificity (100%), but poor sensitivity (42%) of elevated urinary VEGF for PR. Urinary VEGF was also modestly correlated with urinary protein excretion (r(2 ) = 0.23). Correction of VEGF values for urinary protein abrogated any correlation with PR.
Conclusions:
Urinary levels of VEGF are associated with PR, but this relationship may be caused by concurrent renal diseases that result in proteinuria and/or renal VEGF production. The insensitivity of the association may preclude its use in screening to avoid eye examinations.