Sunday, January 25, 2009

Can dialysis prevent nephrogenic systemic fibrosis?

There has been a lot of literature over the past few years regarding the identification of gadolinium-based contrast dye as the driving force behind the dermatologic fibrosing condition nephrogenic systemic fibrosis (NSF). While there remain doubters that gadolinium has definitively been shown to be the cause of this disease--an admittedly difficult claim in that the condition is overall pretty rare and the key epidemiologic studies use case numbers that are small--this theory has by and large been accepted by most nephrology departments.

At our institution, the official policy is to NOT give gadolinium to any patient with ESRD or advanced (Stage 4 or greater) CKD. Despite this policy, one could envision circumstance in which an individual with advanced renal failure is administered gadolinium dye--either if there is an oversight (e.g., the creatinine is not checked before doing the MRI) or if the benefit of doing a particular gadolinium-enhanced contrast study is so great that it outweighs the risk of NSF--which appears to be a pretty low risk in any case. The question arises in these instances: should dialysis be performed to "dialyze off" the gadolinium and therefore minimize the risk of NSF?

On the surface, the answer might seem to be yes: studies have shown that 68% of gadolinium is eliminated after a 3-hour dialysis session and approximately 98% could be removed after three consecutive dialysis sessions. However, most of the available evidence would say that dialysis is *not* effective in preventing gado-induced contrast injury. Several ESRD patients with NSF have been identified in which daily dialysis was initiated within 9-21 hours of being given gadolinium, proving that this strategy is not likely to be uniformly effective for prevention. It is postulated by some that the Gd3+ ion dissociated from the parent dye compound then deposits in tissue within a dialysis-inaccessible compartment--if this process occurs quickly, then one might guess that only dialysis initiated immediately (e.g., within a few hours) after dye exposure would be beneficial.

One could argue that much of the acceptance by nephrologists of the gadolinium-NSF link is out of a medicolegal necessity, due to the many lawfirms taking cases of dialysis patients administered gado-containing contrast. I would imagine that for the most part these current lawsuits are being directed at the manufacturers of contrast dye, though it's a good bet that such lawsuits could in the future target physicians who "knowingly gave a patient a substance contraindicated in patients with kidney disease."

No comments: