Iodinated contrast media
can damage the kidneys.
CO₂ is the safe alternative.

Yes, iodinated contrast media can damage the kidneys in certain patients. This is known as contrast-induced nephropathy or, in its more severe form, AKI (Acute Kidney Injury).

The risk is low in patients with healthy kidneys (1–5%), but increases significantly with reduced renal function, diabetes, dehydration, advanced age, or use of medications such as NSAIDs and metformin.

This is one of the highest-risk situations. An elderly patient with diabetes and reduced renal function (CKD) has an elevated risk of acute kidney injury if iodinated contrast media is used.

In these cases, many specialised centres use CO₂ as an alternative contrast medium: a gas naturally produced by the body, with no renal toxicity, allowing angiography to be performed safely even in the most fragile patients.

It depends on the degree of impairment. The main parameter is GFR (glomerular filtration rate), derived from blood creatinine:

• GFR > 60: low risk with standard precautions
• GFR 30–60: moderate risk, careful assessment needed
• GFR < 30: elevated risk — seriously consider CO₂ as an alternative

Your doctor should check:

• Creatinine and GFR — recent blood tests
• Hydration — being well hydrated before and after the exam is essential
• Current medications — metformin, NSAIDs and diuretics increase the risk
• Contrast allergies — report any previous reactions
• Diabetes — diabetics are at increased risk of contrast-induced nephropathy

In patients with all three conditions together — renal insufficiency + diabetes + peripheral artery disease — the use of iodinated contrast media carries high risk.

These patients are often ideal candidates for CO₂ angiography, which allows the leg arteries to be studied without exposing already compromised kidneys to further risk.

The main preventive measures recommended by international guidelines:

• Hydration with saline solution before and after the procedure
• Minimum effective dose of contrast media
• Temporary suspension of metformin and NSAIDs in the preceding 48h
• Creatinine monitoring in the following 24–48h
• Evaluation of alternatives such as CO₂ for at-risk patients

CT scan: uses X-rays and iodinated contrast media injected intravenously. Fast and widely used.

MRI: uses magnetic fields without X-rays. Its contrast medium (gadolinium) differs from iodinated contrast and has a different renal risk profile.

Angiography: a specific procedure to study blood vessels. A thin catheter is inserted through the skin (groin or wrist) and contrast media is injected directly into the vessel. It can use iodinated contrast or CO₂.

Lower limb angiography studies the leg arteries — to diagnose or treat circulatory problems (stenosis, occlusions, peripheral artery disease).

The interventional radiologist makes a small puncture in the groin to insert a thin catheter into the artery. Through it, contrast media is injected and real-time images are acquired. With CO₂ the procedure is identical, but instead of iodinated liquid, gas is injected — naturally eliminated through the lungs within minutes.

Does it hurt? The procedure is performed under local anaesthesia. You may feel a warm sensation or mild discomfort during contrast injection, but no intense pain.

How long does it take? From 30 minutes to 2 hours, depending on complexity.

Hospital stay? For a simple diagnostic angiography, you often go home the same day after a few hours of observation. For therapeutic procedures (angioplasty, stenting), 1–2 days may be necessary.

For the patient, the cost of the exam does not change: when performed at a facility under contract with the national health service, CO₂ angiography is reimbursed exactly like traditional angiography.

From a hospital perspective, the cost of CO₂ as a contrast medium is lower than traditional iodinated contrast. In addition, by reducing the risk of acute kidney injury (AKI), it avoids the additional costs linked to prolonged hospital stays and emergency dialysis — with significant estimated savings for centres that adopt it systematically.

Yes, the scientific literature is extensive and rapidly growing. Among the most relevant:

• A prospective Italian multicentre study (Chisci et al., Eur J Vasc Endovasc Surg 2025) on 293 patients demonstrated the feasibility and safety of the zero-iodine protocol in over 80% of cases.
• A systematic review by the ESUR (Wawer Matos Reimer et al., European Radiology 2025) confirmed the safety profile of CO₂ as an alternative vascular contrast agent.
• The KID Trial (Saratzis et al., BMJ Open 2025) is the first ongoing randomised controlled trial specifically designed to evaluate kidney injury prevention with CO₂.

For full sources with PubMed links, see the physicians section →

In the first 24–48 hours:

• Drink plenty of water to help the kidneys eliminate the contrast medium (if iodinated)
• Rest for the indicated time, avoid intense physical exertion
• Monitor the access site: small bruises are normal, but report swelling, bleeding or increasing pain immediately
• Do not drive in the following 12–24h if you received sedation

If you had iodinated contrast media: have a creatinine check after 24–48h, especially if you are at renal risk. If you have diabetes and take metformin, wait for your doctor's clearance before resuming it.

With CO₂: follow-up is simpler — since there is no renal risk from the contrast, a specific post-procedure creatinine check is not necessary.