I wish I had known.

[JohnEGreen]

I had a CT scan done yesterday with contrast they never asked and I did not know that there are issues with this and metformin if you also have low egfr

"Metformin is used in type 2 diabetes mellitus to decrease the amount of glucose produced by the liver and to increase the body’s response to insulin. In patients with renal failure (acute or chronic), the renal clearance of metformin is decreased, and there is an associated risk of lactic acidosis, which has a mortality rate of up to 50%.1 Some patients who receive intravenous contrast may experience a deterioration of renal function (contrast-induced nephropathy). Although the points in this article discuss the use of intravenous contrast, the same principles apply to intra-arterial contrast."

"For most patients, metformin should be stopped at the time of contrast administration
There is some controversy about when to stop and restart metformin for patients scheduled to undergo intravenous contrast-enhanced examinations. The guidelines from the Canadian Association of Radiologists2 state that patients taking metformin who have an estimated glomerular filtration rate (eGFR) of less than 60 mL/min should stop taking metformin at the time of contrast administration. The European Society of Urogenital Radiology advocates stopping metformin 48 hours before CT for patients with an eGFR of less than 45 mL/min."

My eGFR is 50 and I am taking metformin.

"Guidelines from the Canadian Association of Radiologists2 state that patients taking metformin who have an eGFR of less than 60 mL/min should restart the drug no sooner than 48 hours after contrast administration and only if renal function remains stable (< 25% increase in creatinine above baseline). Patients with an eGFR above 60 mL/min who receive a larger amount of intravenous contrast (> 100 mL; e.g., CT of the abdomen or pelvis, CT angiography of the aorta or lower extremities) should restart metformin no earlier than 48 hours after the procedure."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3537815/

 

[zand]

Well how daft that they didn't tell you!

Edit: Are you OK John?

 

[Antje77]

When will you know if you got away with this? Or are you having poblems already?

 

[JohnEGreen]

Well how daft that they didn't tell you!

Edit: Are you OK John?

During the scan they asked are you taking metformin I said yes they said OK no problem.

They never asked about eFGR at all and did not say any thing about holding off on it.

I feel not too bad at the moment but think I have been put at serious risk and to be honest I am unsure if I am still at risk or not as I have continued with my metformin.

 

[Antje77]

I'll keep my fingers crossed that this will be one of those 'happens to 1 in 10.00 people' side-effects and you won't be that 1!

 

[carol43]

Hope everything is OK John xxx

 

[ziggy_w]

It's shocking they did this, @JohnEGreen. Keeping my fingers crossed that everything will be okay.

 

[JohnEGreen]

When will you know if you got away with this? Or are you having poblems already?

I'm not sure I have not been feeling too great today but as I said not too bad so far, but some of the symptoms described for lactic acidosis are similar to what I experience on a daily basis so will just have to wait and see

Edit I am a little anxious though. I posted this thread mainly to bring to peoples notice that there can be issues as I did not know till this evening when I did a google search.

 

[kitedoc]

Hi @JohnEGreen, radiology.uscf.edu CT and Xray Contrast Guidelines state that a patient prescribed Metformin and with no sign of acute kidney infection and a GFR of equal or greater than 30 ml/min/1.73 m2 need not stop metformin or require testing of renal function after a procedure using radiological contrast. I hope this reassures you.

 

[Lally123]

During the scan they asked are you taking metformin I said yes they said OK no problem.

They never asked about eFGR at all and did not say any thing about holding off on it.

I feel not too bad at the moment but think I have been put at serious risk and to be honest I am unsure if I am still at risk or not as I have continued with my metformin.

I haven't worked on the wards for about 10 years but I do remember that we used to atop metformin until 48 hrs after contrast with repeat blood test after that time in patients with a lower eGFR. But then the guidelines changed and we no longer had to stop if eGFR was above 30. That was 10 years ago and I don't know whether the guidelines have changed again since then. I wouldn't worry too much as you've carried on with metformin but if you are worried speak to your gp and get your kidney function rechecked 48 hrs post scan. If all is well then you're not at risk. Hope that helps a little.

 

[JohnEGreen]

Hi @JohnEGreen, radiology.uscf.edu CT and Xray Contrast Guidelines state that a patient prescribed Metformin and with no sign of acute kidney infection and a GFR of equal or greater than 30 ml/min/1.73 m2 need not stop metformin or require testing of renal function after a procedure using radiological contrast. I hope this reassures you.

Thanks for that @kitedoc that helps mitigate my anxiety a great deal and I will take their word for it yet there are issues and I was not asked nor did they seem to be aware off my renal deficiency my last eGFR was 50 but that was some time ago and it has been dropping steadily over a protracted period I don't know and neither did they what it actually is as of now.

 

[JohnEGreen]

@Lally123 thanks I am still a little anxious but feel it's bit bit late to worry now and there as you say is probably not too much cause for concern after all.

So am not panicking so much now.

However though I see now that the article is a little dated going back to 2013 I think, that still comes after guidelines were amended and it does say there was controversy about it then.

I am pretty sure they are probably right but would not normally want to stake my life on it.

And not withstanding all that they asked me virtually at the point when I was all hooked up with needle in arm and the scan about to start if I was diabetic almost as an after thought and when I replied yes they then asked if I was taking metformin and did not even ask about renal complications.

I do not think that is good practice.

A few days abstinence from metformin would not be critical and if I had known never mind modified guide lines I would have stopped taking it before the scan and would have not started taking again for a couple of days just to be on the safe side.

 

[kitedoc]

Hi @JohnEGreen, I agree that your experience suggests a rather casual attitude by Xray staff and put you under unnecessary strain.
The Xray forms I have seen actually request the doctor ordering the test to write in the patient's eGFR level for any imaging involving radiological contrast as well as a tick box for whether the patient is prescribed Metformin.
I believe that for those persons within a certain range of low eGFR there is a medication that can be infused prior to the scan with contrast and this medication prevents the contrast injuring the kidneys but this also involves cessation of metformin for some time ?48 hours) beforehand.
There will, of course, be patients with eGFR levels where use of radiological contrast is a complete no-no.
I hope your CT scan results are satisfactory, and it might be worth thinking about delicately asking your doctor why he/she did not add to your CT scan request form the fact that you are prescribed Metformin and what your eGFR was.
Such foresight could have saved you much worry.

 

[JohnEGreen]

I think that in all probability they may have been a little distracted by the fact they were running somewhat late and it was towards the end of their working day.

Edit As an after thought I think also the question of comorbidity comes into play the doctor requesting the scan is my neurologist he is more than likely not familiar with diabetes as such or the complications arising from it regarding metformin and other diabetic medications so may not have been aware of the necessity.

 

[Deleted member 308541]

The Xray forms I have seen actually request the doctor ordering the test to write in the patient's eGFR level for any imaging involving radiological contrast as well as a tick box for whether the patient is prescribed Metformin.

I happen to have imaging request form from my GP to the radiology shop, and there is a list of boxes to tick either yes or no

Contrast Allergy Y/N
Renal Disease Y/N
Diabetes Metformin treatment Y/N,
Creatine Level ____
eGFR ____
Date ____

There are other boxes to tick but have nothing to do with the above so have not included them.

 

[JohnEGreen]

Maybe if she had read the form if it is the same here as it is there then she would not have had to ask me, which she did.

Edit to add for the short time I practiced as a health practitioner I never touched a patient unless I had read their notes.

 

[Antje77]

Maybe if she had read the form if it is the same here as it is there then she would not have had to ask me, which she did.

Edit to add for the short time I practiced as a health practitioner I never touched a patient unless I had read their notes.

That would instantly qualify you as my health practitioner

 

[DavidGrahamJones]

I had a CT scan done yesterday with contrast they never asked and I did not know that there are issues with this and metformin if you also have low egfr

I've had two CT scans, one in the U.S. and one in the U.K. No questions asked, slightly worrying.