New Mexico Geological Society Annual Spring Meeting — Abstracts

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Gadolinium-based contrast agents (GBCAs) are essential tools in magnetic resonance imaging (MRI) and are widely used to enhance diagnostic precision. To safely harness gadolinium’s paramagnetic properties, it is chelated with proprietary polyaminocarboxylic ligands that promote renal elimination and reduce toxicity. However, widespread and repeated use of these agents has contaminated surface and municipal waters, raising concern about chronic low-dose environmental exposure.

In 2006, Dr. Thomas Grobner reported that GBCAs could induce nephrogenic systemic fibrosis (NSF), a scleroderma-spectrum disorder, in patients with renal impairment. Since then, concerns have expanded to include gadolinium retention in patients with normal kidney function and the possibility of chronic complications following exposure to intravenous contrast agents—or environmentally through drinking water. Gadolinium retention follows a three-phase model: rapid, intermediate, and long-term.

Methods: We quantified gadolinium concentrations in urine, blood, hair, and nail samples from participants with known dates and cumulative MRI contrast agent exposure doses. Semi-logarithmic regression plots were used to derive best-fit models for intermediate-phase elimination.

Results: We recruited 118 contrast-exposed participants (71.2% women, 59.9 ± 10.6 years) and 22 contrast-naïve participants (59.1% women, 46.9 ± 20.6 years). Data were missing for urine in 8 subjects, blood in 3, and nails in 2. The contrast-exposed group reported an average of 2.1 ± 1.4 lifetime GBCA exposures, with a mean cumulative dose of 27.8 ± 18.8 mL. Time from last exposure to sample collection was highly variable (mean 537 ± 980 days; range 0 to 5,670 days). Reported contrast agent brands included ProHance (32.2%), MultiHance (26.3%), unknown (18.6%), Dotarem (11.0%), Gadavist (6.8%), Magnevist (3.4%), and Eovist (1.7%).

Among contrast-exposed participants, gadolinium was detectable in 69.5% of urine samples, 44.9% of blood samples, 92.4% of hair samples, and 94.9% of nail samples. In contrast-naïve individuals, gadolinium was found in the urine of one subject (4.8%), in the serum of two subjects (9.5%), and the hair (95.2%) and nails (95.0%) of most participants—suggesting potential environmental exposure.

Quantitative values were markedly different between groups:

• Urine gadolinium: 0.3 ± 1.2 mcg/24 h (naïve) vs. 54.7 ± 48.2 mcg/24 h (exposed)

• Blood gadolinium: 0 ng/mL (naïve) vs. 394 ± 394 ng/mL (exposed)

• Hair gadolinium: 0.1 ± 0.1 mg/kg (naïve) vs. 0.4 ± 0.1 mg/kg (exposed)

• Nail gadolinium: 0.12 ± 0.04 mg/kg (naïve) vs. 0.53 ± 0.17 mg/kg (exposed)

Serum gadolinium levels correlated significantly with urine gadolinium (multiple r² = 0.38, adjusted r² = 0.37, p = 1.1 × 10⁻¹²). Notably, urine gadolinium was frequently detectable when serum levels were below the reporting threshold (n = 33), whereas only one case showed detectable serum gadolinium with undetectable urine levels.

Regression modeling revealed strong intermediate-phase elimination fits:

• For urine gadolinium < 50 days post-exposure: r² = 0.63, p = 0.00001

• For blood gadolinium < 25 days post-exposure: r² = 0.73, p = 0.03

The resulting predictive equations for intermediate clearance were:

Gd[urine] = e^(6.1 - 0.1t) [1]

Gd[serum] = e^(7.8 - 0.4t) [2]

Where t represents days since the last contrast exposure.

Conclusions. Gadolinium is consistently detectable in multiple tissue compartments long after GBCA exposure, particularly in hair and nails, which serve as reservoirs of cumulative retention. Contrast-naïve participants also showed evidence of gadolinium in keratinized tissues, possibly due to environmental exposure or unrecognized medical contact.