Iodine Excess
1) Iodine excess may happen if you have been exposed to high doses of radiographic contact dyes. The US Food and Nutrition offices list this iodine excess as anything over 1,100 µg/L/24 hr urine test while the World Health Organization says anything over 1,000 µg/L/24 urine test. Iodine toxicity is considered by WHO as anything over 1,700 mcg/test which has some serious health risks including autoimmune hypothyroidism.
The following information applies to Hypaque, MD 76R, MD Gastroview, Gastrografin and Urografin and is taken from their package inserts for both their cat scan and enema products.
"Drug/Laboratory Test Interactions
Thyroid Function Tests
The results of protein bound iodine (PBI) and radioactive iodine uptake studies, which depend on iodine estimations, will not accurately reflect thyroid function for six months, and possibly as long as one year, following the administration of diagnostic enteral radiopaque media.
Thyroid function tests, if indicated, generally should be performed prior to the administration of any iodinated agent. However, thyroid function can be evaluated after use of these agents by using T3 resin uptake and total or free thyroxine (T4) assays which are not dependent on iodine estimations."
2) Iodine induced hypothyroidism The medical literature well documents that high intake of iodine causes elevated TSH and lowered T3 and T4 (Wolff-Chaikoff effect, references available).
Research shows a 10 to 28% occurrence of hypothyroidism from a single iodine contrast test. (see below)
Source Reference: Pearce EN "Iodine-induced thyroid dysfunction: Evaluating the risks of iodinated contrast medium "Arch Intern Med 2012; 172(2): 159-161.
Source Reference: Rhee CM, et al "Association between iodinated contrast media exposure and incident hyperthyroidism and hypothyroidism" Arch Intern Med 2012; 172(2): 153-159.
3) Amount of estimated iodine still left in me at May 29th urine iodine test.
Most contrasts contain 300 to 370 mg of iodine per ml.
Contrast CT scan - Dec 29th/2014 - My urine test was 149 days after my cat scan. At a 64 day excretion half-life I would still have about 21% of the iodine left in me. Approximately 6.1 grams.
In my case:
Contrast CT scan - Dec 29th/2014 - Used 100 ml of Isovue 370 which is composed of 370 mg/ml. A 100 ml dose calculates to 37 grams iodine. Which is the same as the daily recommended intake (150 micrograms/day) for 250,000 days (685 years).
My 24 hour urine iodine was 1238 on May 29th/2015 and had dropped to 187 by Nov. 19th of 2015.
Note
With iodine contrast barium enemas the serum iodine increases 10 to 200 times beginning baseline levels.
Normal Serum Iodine
52-109 µg/L
This would then elevate to 520 to 20,000 µg/L from a single iodine/barium enema.
4) Drugs used for cat scan and iodine enemas:
Hypaque
(Diatrizoate Sodium, USP) is sodium 3,5-diacetamido-2, 4, 6-triiodobenzoate (C11H8I3N2NaO4)
Used in enemas and oral. Enema, from 500 mL to 1000 mL of a 15 to 25 percent solution. Which provides 9 to 25 grams of iodine.
MD 76R
Cat scan contrast media. Each mL contains approximately and 370 mg of organically bound iodine. Fifty to 100 ml used which supplies about 20 to 40 grams of iodine.
MD Gastroview
(Diatrizoate Meglumine and Diatrizoate Sodium Solution)
Used in enemas and orally. Each mL contains approximately 367 mg organically bound iodine. When used as an enema, the suggested dilution for adults is 240 mL (88 g iodine) in 1,000 mL of tap water.
Gastrografin
(Diatrizoate Meglumine and Diatrizoate Sodium Solution)
Used in enemas and orally.. Each mL contains approximately 367 mg organically bound iodine. When used as an enema, the suggested dilution for adults is 240 mL (88 g iodine) in 1,000 mL of tap water.
Urografin
Sodium amidotrizoate and meglumine amidotrizoate in a proportion of 10:66 in aqueous solution (formed from amidotrizoic acid or diatrizoic acid:3,5-bis-acetamido-2,4,6-triiodobenzoic acid).
Used in cat scans. Each mL contains approximately 370 mg organically bound iodine. Dosage for adults is 50 ml or more. This provides a minimum of 20 grams of iodine.
The amount of iodine given to a patient is from 9 to 88 grams per contrast imaging. This is 90,000 to 880,000 times the RDA.
Iodine RDA - 120 µg/day - Adult Male
5) Elimination half-life
The biological removal half-life of radioactive iodine in the body is a 50% elimination every 64 to 80 days.
Average 57 days with a range of 11 to 4000 days.
60 days to return to normal (21 patients)
6) Misc.
Note - The Wolff–Chaikoff effect is a presumed reduction in thyroid hormone levels caused by ingestion of a large amount of iodine.
FYI; In each of these studies it was noted that in a small percentage of participants 'escape' from the Wolff-Chaikoff effect did not occur and presented as a chronic condition, especially noted in the elderly.
Repetitive contrast media exposure in a short period of time eliminates the 'escape' from the Wolff-Chaikoff effect. Resultant hypothyroidism may last for years. Numerous references included.
Iodine excess (>1,000 micrograms/day, urine test) eliminates the 'escape' from the Wolff-Chaikoff effect. Resultant hypothyroidism may last for years.
The estimated glomerular filtration rate (eGFR) should be no lower than 30 mL/min in patients receiving iodinated contrast, and discretion should be used in patients with eGFR less 45 mL/min
UC San Francisco Guidelines on the Administration of Intravenous Iodinated Contrast Media
Mine runs 70 to 93.
Special Note
According to records from Litton and Gidding (obtained from office manager and with assistance Dr Kevin Baehl I recieved approximately 250 to 300 grams of iodide 123 in my 3 tests from Dec. 29th 2014 to March 24th 2015. A total of 85 days.
