Full-disclosure, we are reporting on our own retention paper.

Today we have released our fourth research paper on gadolinium retention from Gadolinium-based Contrast Agents (GBCAs) administered for contrast-enhanced MRIs. The paper is titled “Gadolinium Retention from Contrast MRIs in 70 Cases with Normal Renal Function – 24-hour Urine Test Results”.

Drawing on the contrast MRI history and 24-hour gadolinium urine testing results information that we have received from members of the MRI-Gadolinium-Toxicity Support Group, we reported retrospectively on 70 cases with 120 urine test results.  We are thankful to the members of our support group for being willing to share their information with us.  The participants all had normal kidney function and report having symptoms of gadolinium toxicity. We believe the results reported are dramatic.

About the Gadolinium Retention Study

The number of results presented is up significantly from our last paper in 2014 when we reported on 15 cases and 40 test results.  The additional data points allowed us to look at gender as a possible differentiator, but the data showed nearly identical test results for males and females.  With information about the number of contrast-enhanced MRIs for each case, we were able to analyze the results in three groups: cases with a single contrast MRI, cases with 2 to 4 contrast MRIs, and cases with 5 or more contrast MRIs.  Readers of this site will not be surprised that the analysis showed that for these cases, there was a discernible difference in test results based on these groupings.  The 2 to 4 contrast group generally had higher levels of gadolinium in their urine for a longer period of time than those with a single contrast.  Likewise, the results for the 5 or more MRIs group were higher longer than the cases in the 2-4 contrast MRIs group.  This is consistent with the cumulative effect of multiple contrast-enhanced MRIs that others have reported.

We also provided the raw test results data for each case, enabling other researchers as well as patients to look at the progression of test results over time.  Averages for time blocks since the last contrast MRI are also shown to help in understanding the progression of gadolinium urine levels.

A few observations regarding the test results are revealing.  21 cases had urine tests performed in the first month with results that range from 507 mcg Gd/24hr urine specimen 4 days after the contrast MRI to results around 17 mcg Gd/24hr near the end of the first month.  All of the results are enumerated in the report.  8 cases had urine test results more than 36 months after their contrast MRI with results as high as 0.6 mcg Gd/24hr more than 7 years after the individual’s last contrast-enhanced MRI.  There is no broadly utilized acceptable range for gadolinium in a 24-hour urine collection. Mayo Clinic has established a reference range that was recently updated to be 0.0-0.6 mcg Gd/24-hour urine specimen collected more than 96 hours after administration of a GBCA.  40 cases had urine tests in the first 3 months after their contrast MRI, with the lowest result being 1.74 mcg Gd/24hr, well above the Mayo reference range that is applicable once four days have elapsed since the contrast MRI.  Simply stated the results we observed are inconsistent with the clearance times indicated on GBCA product labeling and the understanding of most researchers and clinical practitioners.

Final Thoughts

To the best of our knowledge, this is the most comprehensive reporting of retained gadolinium as evidenced by urine testing that is available to the public.  While the methods we used do not meet the rigor of a clinical trial, and we do not know if similar results would be seen universally, we believe the consistency of the results and the lack of outliers on the low side are justification for concern.  We believe that further investigation by researchers, GBCA manufacturers, and licensing agencies is warranted.

This study does not stand alone, but confirms the many recently published research papers that reported unexpected retention of gadolinium from contrast MRIs by people with normal renal function.  We encourage stronger action by the FDA and others to inform patients about possible gadolinium retention from contrast-enhanced MRIs and the potential for long-term side-effects.

We urge patients, clinicians, and researchers to read the entire report and share as appropriate with your families, care-givers, and colleagues.  Read the Report.

Hubbs Grimm and Sharon Williams