Treatment based on antibodies to vascular endothelial growth factor (VEGF) has dramatically improved the management of wet age related macular degeneration. 1 The debate surrounding the off label use of bevacizumab versus ranibizumab raised many issues. However, we were worried by the lack of a caution regarding the potential renal side effects associated with this class of drugs.

VEGF is important in maintaining renal glomerular integrity and function. Patients treated with VEGF inhibitors develop renal side effects including hypertension (3-36%), proteinuria (21-63%), and acute renal impairment (> 25% decrease in creatinine clearance; up to 44%). 2 3 A few develop haemolytic uraemic syndrome. Since 2005, we have identified patients who developed renal thrombotic microangiopathy (small vessel injury) after taking VEGF inhibitors; 23 cases were related to intravenous bevacizumab and one followed intraocular administration of ranibizumab. 4 Similar effects are seen with other drugs that block VEGF and occur after an average of four treatment cycles. Renal thrombotic microangiopathy is often not recognised until the kidney is biopsied. Awareness of renal side effects is limited so patients are not routinely screened. When these side effects occur, the link with anti-VEGF therapy is often not made—for example, the increased risk of stroke could be related to unrecognised hypertension. 5 It is important to highlight these effects given that anti-VEGF drugs are being used more often. With increased awareness and correct monitoring (blood pressure, urine