Ct scan

[France92]

Hi I had to have another ct scan today with contrast second in 5mths for something else. One of the questions they ask if you have a thyroid illness just wondering why? I'm still undiagnosed and being monitored after mine had a blip overactive.

[humanbean]

This is a complete guess...

There are a couple of different kinds of contrast. One of them is iodine-based. Perhaps they avoid iodine-based contrast in people with thyroid disease and use gadolinium-based contrast instead?

[helvella Administrator in reply to humanbean]

Gadolinium contrast is, I believe, only for MRI scans.

I really don't know much about CT contrast. (Actually, effectively nothing.) But this link takes you to tons of info.

radiopaedia.org/search?q=ct...

[tattybogle in reply to helvella]

seems like there are concerns about using it in patients who are already hyperthyroid ? :

iodinated-contrast-induced-thyrotoxicosis

radiopaedia.org/articles/io...

"Iodinated contrast-induced thyrotoxicosis is rare and may occur in patients with pre-existing thyroid disease and through complications of thyrotoxicosis (e.g. cardiac arrhythmia) may be fatal. Patients with a normal thyroid gland are unaffected.

Patients with existing thyrotoxicosis should not receive iodinated contrast medium 3 and high-risk patients (see below) should avoid iodinated contrast unless there is a strong indication 4.

Epidemiology

A recent study has established a strong association between iodine contrast administration and subsequent new hyperthyroidism 1,2. Prevalence in iodine-deficient countries is estimated at 0.25-0.5% and in non-iodine deficient countries is 0.025%, although exact prevalence has yet to be determined.

Risk factors

Patients with multinodular goitre and Graves disease are considered at high risk. Other population groups at risk include:

elderly (due to the increased prevalence of nodular thyroid disease)

people living in areas of endemic iodine deficiency

Pathology

Administration of iodinated contrast results in a large iodine load to the thyroid (at least 90 times the daily recommended intake), which may lead to increased secretion of thyroid hormones (see: Jod-Basedow phenomenon).

Hyperthyroidism develops over 2-12 weeks 1 and is more commonly latent (i.e. clinically silent) than overt (i.e. thyrotoxicosis) 4.

Treatment and prognosis

Various treatment schedules have been proposed for prophylaxis 4, however, it is not unanimously recommended 1. Patients at high risk, especially those with an underlying unstable cardiovascular disease, should have thyroid function tests carefully monitored after administration 1,4. "

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

iodinated-contrast-media-

radiopaedia.org/articles/io...

[France92 in reply to tattybogle]

Thankyou gosh I hope I'm going to be ok my heart did go fast after it was given and feeling bit breathless now. I had no choice as they are unfortunately checking me for cancer so risk both ways. It's strange when I had last ct scan it when they diagnosed me with overactive can't remember if before or after the scan as I was in hospital.

[tattybogle in reply to France92]

yes it's a balancing act isn't it , i decided to allow them to use contrast when looking for cancer ~ not much point letting them do a scan unless you give them a reasonable chance of finding what they are looking for .

They told me to make sure i drank lots of water afterwards and over the next few days to flush it out as quickly as possible . So i did .

( ? it wouldn't have made you overactive 'immediately' after the scan , sounds from that article like it might take a week or two at least to have that affect if it was going to? )

You just need to make sure they are aware of your thyroid history and treatment and see what they advise . If you are concerned ask someone to discuss the risks with you before the scan

[France92 in reply to tattybogle]

Thanks I had the scan this morning. They did it quick and put contrast in quick and said it was safe.

[serenfach in reply to tattybogle]

Interesting. I had a scan but the lad was new and overdosed me with iodine. I was hospitalised after the scan with a severe reaction. The scan results were in my file, but the hospital denied I had had a scan! My thyroid problems started then,

Lately I refused a contrast scan using iodine, and a huge fuss was made, telling me I was being silly. I agreed to the scan if they had the cardiac team standing by. I had the scan without the contrast, but they did not bother getting me undressed. My bra underwires and the rivets on my jeans came through very clearly!

I am now allergic to iodine, which is a shame because you use it a lot when lambing.

[tattybogle in reply to serenfach]

Mmm ...... must admit i wasn't very reassured by their 'safety reassurance' when i had mine done

(did your alleged 'prostate' show up ?)

[France92 in reply to serenfach]

I'm so sorry you went through that. I had to keep my clothes on they did sat wear lose clothing. I'm not feeling good at all since I've had it I had it because I'm poorly now feel worse. I'm drinking loads trying to get it out of my system im sure I can smell it up my nose.

[Framboise]

I had an iodine contrast for a first CT scan of my lungs, arranged because an MRI of my shoulder had picked up something suspicious. I decided it was worth any risk, and that not using it carried more of a risk of missing something. I was asked about thyroid problems but they didn't seem concerned when I told them, went ahead, and I didn't notice any side effects at all.

However, once they know what they're looking at, you shouldn't necessarily need contrast for future scans. I had an annual scan for a further four years, queried the contrast at the second one, and after some discussion they said I wouldn't need it (the contrast) any more as they knew exactly what they were looking at and monitoring now.

Something I wasn't aware of at the time is that a dire-looking signal in an MRI scan can turn out to be harmless in a CT scan - thank goodness for modern technology! I truly hope your results show a similarly good outcome.

[France92 in reply to Framboise]

Thankyou

[Miffie]

I have had contrast dies on three occasions that I can remember since I was diagnosed with hypothyroidism. Apart from the not feeling great when it’s first administered I have had no ill effects. Last one was three years ago as I recall. Drinking plenty to flush the system was recommended. Good luck

[France92 in reply to Miffie]

Thankyou