Allergic reactions to MRI scans with contrast dye are unlikely

Dear Dr. Roach: My primary care doctor has ordered that I get an MRI scan with and without contrast dye. I have been having head pain every day in one single spot behind my right eye. My question is, is gadolinium (the contrast dye that will be injected to enhance pictures of my brain) safe? I have been reading that people can get allergic reactions to this dye.

I am sensitive to medications and have spoken to my doctor about my concerns, but he sees no problem with the dye. I have to get blood work two weeks ahead of time to check if my kidneys can handle the dye. How would I know for sure if I am allergic to gadolinium?

M.B.

Answer: Gadolinium is given for most MRI scans of the brain to help diagnose abnormalities. Allergic reactions are rare, less than one per 1,000 people. Although skin allergy tests do exist with gadolinium, they are not routinely recommended. Dye for CT scans is more likely to cause allergic reactions.

Kidney damage rarely occurs with gadolinium dye in people with kidney disease. Some brands of gadolinium are more prone to causing this than others. If your blood tests show that your kidneys are OK, your risk of this is very low.

Dear Dr. Roach: My annual exams, starting in 2007, show a high total cholesterol over 200 mg/dL and an LDL count over 100 mg/dL, but my HDL count has averaged 67 mg/dL. My recent cholesterol-to-HDL ratio has averaged 3.0. My cardiologist recently started me on 20 mg of pravastatin and 5 mg of amlodipine for high blood pressure. I question the need for either one.

My primary care physician (from 2007-2021, now retired) saw no need for any cholesterol or high blood pressure medication. My blood pressure averages 145/70 mm Hg, and my pulse rate averages 52 BPM. My stress test was negative. My age is 83, and I play pickleball four days a week and exercise the rest of the week.

D.O.

Answer: You are at risk largely because of your age, but also because both your cholesterol and blood pressure, though not very high, are not optimal. Making some assumptions, and putting your information into a standard risk calculator (one can be found at tiny url.com/w7759yh), I found you have a 36% chance of having a heart attack, stroke or death due to heart disease in the next 10 years. Your cardiologist recommended treatment that will reduce your risk. With optimum control of blood pressure and cholesterol, your risk could be as low as 24%. Those numbers are only a starting place. Because of your active lifestyle and negative stress test, your risk is probably lower than the average 83year-old on whom these numbers are based, so you may not get quite as much benefit as a person who isn’t as active.

I don’t tell my patients they “need” to take medication to reduce their risk; rather, I try to present the options. Some of my patients really don’t want to take medicines and are content with their risks the way they are. Others are more willing to try medication to reduce their risk and will keep taking them as long as there aren’t any side effects. Still, others want to get more information to help guide their decision, such as a coronary calcium score or a C-reactive protein test, both of which can help refine the estimate of benefit from treatment.