CT Scan with Non-Ionic Contrast: Risks for Diabetic Patients and Medication Guidelines

Recently, I need to undergo a CT scan of the brain with non-ionic contrast agent?

I have a history of type 2 diabetes for 8 years, and my kidney function is currently normal based on blood tests.
I am scheduled for a CT scan of the brain and will be receiving a non-ionic contrast agent.
My medications include:
Metabolism Department:
- Metformin HCl 850 mg
- Lyrica (Pregabalin) 75 mg, 2 capsules
Psychiatry:
- At bedtime: Lyrica (Pregabalin) 75 mg, 2 capsules
- Zoloft (Sertraline) 50 mg, 2 capsules
- Mirtazapine 50 mg, 2 capsules
- Clonazepam 50 mg, 1 capsule
- Zolpidem 10 mg, 2 capsules
- Flunitrazepam 2 mg, 2 capsules
- Alprazolam 0.5 mg, 2 capsules
Otolaryngology:
- Loratadine 10 mg
Urology:
- Tamsulosin 0.2 mg, 2 capsules
- Baclofen 5 mg, one capsule in the morning and evening
- Bethanechol chloride 25 mg, three times a day
Cardiology:
- Somil S.C.
Tab - 40 mg, 60 mg
1.
Is there a possibility that the non-ionic contrast agent could lead to chronic kidney failure? I noticed in the consent form from the hospital that it mentions a high risk of kidney failure in diabetic patients.
Is this referring to acute kidney failure or chronic kidney failure?
2.
Among the medications listed above, which ones should I stop taking 5 days or 1 week prior to the procedure, and how many days after the procedure can I resume taking them? Thank you, doctor.

Niming, 30~39 year old female. Ask Date: 2020/09/22

Dr. Huang Yaoxuan reply Internal Medicine

Please visit the nephrology outpatient clinic to discuss the effects of non-ionic contrast agents on renal function.
According to the UpToDate database, specifically the section on "Prevention of contrast-induced acute kidney injury associated with computed tomography," the following points are noted:
1.
2016 US Food and Drug Administration (FDA): It is recommended that all patients undergoing imaging studies with iodinated contrast media temporarily discontinue metformin.
Metformin is not advised for patients with an estimated glomerular filtration rate (eGFR) between 30 to 60 ml/min/1.73m² due to concerns that acute kidney injury from iodinated contrast media could lead to metformin accumulation and subsequent lactic acidosis.
However, the authors of UpToDate believe that in patients with an eGFR above 60, or between 30 to 60 without risk factors, the risk of acute kidney injury from iodinated contrast media is negligible, thus there is no need to discontinue metformin.
2.
2018 ACR Guidelines: In patients with risk factors for contrast-induced acute kidney injury (CI-AKI), metformin should be withheld for at least 48 hours.
If there are no risk factors, there is no need to discontinue metformin.
The above information is for reference only; it is still recommended to discuss clinical situations with a physician.

Reply Date: 2020/09/22

More Info

When it comes to diabetic patients undergoing a CT scan with non-ionic contrast agents, there are several important considerations regarding the potential risks to kidney function and medication management.

Risks of Non-Ionic Contrast Agents in Diabetic Patients
1. Kidney Function and Contrast-Induced Nephropathy (CIN):
Diabetic patients are at an increased risk for developing contrast-induced nephropathy (CIN), particularly if they have underlying kidney issues. However, since your renal function is currently normal based on blood tests, the immediate risk of CIN is lower. The term "acute kidney injury" (AKI) is often used in this context, which refers to a sudden decline in kidney function that can occur after exposure to contrast agents. Chronic kidney disease (CKD), on the other hand, is a long-term condition that develops over time. The consent form you received likely refers to the risk of AKI, which can potentially lead to CKD if not managed properly.

2. Monitoring and Precautions:
It is crucial to monitor kidney function before and after the administration of contrast agents. The American College of Radiology (ACR) guidelines suggest that for patients with normal renal function, the use of non-ionic contrast agents is generally safe. However, it is always advisable to discuss your specific situation with your healthcare provider, especially considering your diabetes history.

Medication Management
1. Metformin:
Traditionally, it was recommended to hold metformin for 48 hours before and after the administration of iodinated contrast media due to the risk of lactic acidosis, particularly in patients with compromised renal function. However, recent guidelines indicate that if renal function is normal, metformin can often be continued. It is essential to check your creatinine levels post-CT scan to ensure they remain within normal limits before resuming metformin.

2. Other Medications:
The other medications you are taking, such as pregabalin (Lyrica), Zoloft (sertraline), and others, do not typically require discontinuation before a CT scan. However, it is always best to consult with your prescribing physician or pharmacist regarding any specific concerns about interactions or the need to pause any medications.

3. Timing for Resuming Medications:
If you do need to hold metformin or any other medication, your healthcare provider will give you specific instructions on when to resume them. Generally, you can restart medications like pregabalin, Zoloft, and others shortly after the procedure unless otherwise advised.

Conclusion
In summary, while there is an increased risk of acute kidney injury in diabetic patients undergoing CT scans with non-ionic contrast agents, your current normal renal function is a positive indicator. It is crucial to have a thorough discussion with your healthcare provider about the risks and benefits of the procedure, as well as the management of your medications. Always ensure that your healthcare team is aware of all the medications you are taking, as this will help them provide the best care tailored to your needs.
Make sure to follow up with your doctor after the CT scan to check your kidney function and discuss when to safely resume any medications that may have been paused.

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