Gadolinium-associated nephrogenic systemic fibrosis: the need for nephrologists' awareness.

Nephrogenic systemic fibrosis (NSF) / nephrogenic fibrosing dermopathy (NFD) is a recently described disease, occurring only in patients with variable degrees of renal failure (RF) previously exposed to gadolinium-based contrast agents (GBCAs) for magnetic resonance imaging. Public advisories are consistent on some key points including that no cases of NSF/NFD have been reported in patients with normal renal function, and GBCAs may be toxic in patients with RF due to the prolongation of the half-time allowing dissociation and extravasation of highly toxic gadolinium-free ions, potentially linked to the scleroderma-like NSF/NFD, a systemic disabling disease with a mortality rate of up to 30%. The most intriguing feature remains which cofactor might be at play to explain why the disease occurs only in a minority of exposed patients. Therefore, renal dysfunction (substrate) and gadolinium chelates (trigger agent) are necessary but not sufficient. The challenge for nephrologists includes (a) evidence of transmetallation, such as gadolinium deposits in bone, increased urinary zinc excretion, iron-transferrin dissociation or "spurious hypocalcemia" in exposed people; (b) research for uremic cofactors such as increased serum calcium/phosphate, acidosis, use of phosphate-chelating agents able to act as efficient competitor ligands or other drugs; and (c) identification of at-risk patients (with moderate to severe renal dysfunction) and definition of the role of dialysis in removing gadolinium chelates, if any. Nephrologists are called to action to collect and organize information to identify cofactors for NSF/NFD, and therefore they must be aware of this new pathology, as the eye sees only what the mind knows.