|Values are valid only on day of printing.|
An aid in documenting past exposure to gadolinium-containing chelates
Gadolinium is a member of the lanthanide series of the periodic table of elements and is considered a nonessential element. Due to its paramagnetic properties, chelated gadolinium is commonly employed as contrast media for magnetic resonance imaging and computer tomography scanning.
Gadolinium is eliminated primarily by renal filtration. In healthy subjects with normal renal function, the plasma half-life of gadolinium is approximately 90 minutes. Patients with reduced renal function exhibit an increased gadolinium excretion half-life.
Gadolinium has been associated with the nephrogenic systemic fibrosis in patients with impaired renal function. In this syndrome, prolonged retention of gadolinium is thought to allow the gadolinium cation to dissociate from its synthetic organic chelator and deposit predominantly in the skin, although other organs may be affected as well. These patients are often severely debilitated by progressive skin thickening and tightening. Fibrosis of skeletal muscle, lungs, liver, testes, and myocardium have all been observed, often with fatal results. Because the ionic radius of gadolinium (3+) is similar to that of calcium (2+), it may also deposit in bone.
Reference values apply to all ages.
Elevated gadolinium (>0.5 mcg/L) observed in a random urine specimen collected >96 hours after administration of gadolinium-containing contrast media may indicate impaired ability to eliminate gadolinium or continued exposure, suggesting either reduced renal function or exposure to anthropogenic sources. Patients with reduced renal function who have been exposed to gadolinium may have an increased risk to develop nephrogenic systemic fibrosis.
The normal value is <0.5 mcg/L; 95% of unexposed patients will have values <0.1 mcg/L. The lower limit of detection is 0.1 mcg/L.
Urine gadolinium concentration may be elevated if the specimen is collected <96 hours of administration of gadolinium-containing contrast media. This elevation is due to residual gadolinium present from contrast media infusion. Elevated gadolinium in a specimen collected <96 hours after contrast media infusion does not indicate risk of nephrogenic systemic fibrosis (NSF).
Evaluation of urine for gadolinium content has minimal value in making the diagnosis of NSF. Gadolinium is present in the effluent of metropolitan sewage treatment plants and in the rivers near metropolitan areas. Sewage treatment does not remove gadolinium. Anthropogenic sources of gadolinium could contribute to low concentrations of gadolinium excreted in the urine.
An evaluation of urine gadolinium concentration in healthy human subjects not exposed to gadolinium within 96 hours of specimen collection generated a reference range of <0.1 to 0.5 mcg/L (median value 0.2 mcg/L) with no evidence of age or gender trend. Urine gadolinium concentrations observed in Mayo Clinic patients with nephrogenic systemic fibrosis (NSF), either before or after chelation therapy with succimer, were in the range of 2 to 5 mcg/L (ie, succimer had no effect on excretion rate). No peer-reviewed reports of urine gadolinium concentrations associated with NSF were found on literature search.
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