DEAR DR. ROACH: I used to give blood regularly. While in the Air Force, I was stationed in England for four years in the early 1980s. Sometime in the 1990s, I was told that due to concern about mad cow disease, I would no longer be able to donate. Is that still true? If so, what do people in the United Kingdom do, since it would seem no one would be eligible to be a donor? — G.A.
ANSWER: The U.S. Food and Drug Administration recently lifted the previous restrictions on blood donation from service members and civilians who lived in the U.K. or in Europe. People suspected of having variant Creutzfeldt-Jakob disease (vCJD, so-called “mad cow” disease), those who have a family history of any similar disease, and a few other people at high risk are still prohibited from donating.
There have only ever been a handful of cases spread by blood transfusion. In the U.K. during the epidemic, there were measures put into place to reduce risk, and there were very few cases transmitted, despite most people being able to donate. (In the U.K., people who received a blood donation during the most dangerous time of this disease were ineligible to donate blood.)
Blood banks always consider the real and perceived risks of the donated blood, as well as the danger that they might be turning away so many people that they can’t deliver all the blood they need. Blood banks are extremely averse to taking risks and often turn away blood that is very, very likely safe. I’m glad they have made this change.
DEAR DR. ROACH: I am 72 years old, and I do strength training and walk. From 2018 to 2020, my DEXA scan showed minimal bone loss. This year, I lost a significant amount in my hips. I had greater loss in my left hip than my right. Why would there be such a difference in one hip? It would seem bone loss would be the same in each hip. — L.D.
ANSWER: Bone loss is usually similar in both sides, except in people with obvious medical reasons why there wouldn’t be (such as a history of stroke or other cause of weakness on one side). I suspect that what has happened is a result of the error inherent within DEXA measurements.
No matter how good the laboratory is, or how diligent the professionals who perform the millions of laboratory and radiology procedures done every year are, every measurement has the possibility of random error. This amount of error is usually very small and does not make a difference in interpreting the results of a study, but a clinician must always be aware of this possibility. With DEXA (dual-energy X-ray absorptiometry) scans in particular, the amount of variability possible between one scan and another scan, just due to random factors, is large enough that it must be considered. Often, a trend over time, even over several years, is necessary to confirm that a treatment is or isn’t working, or that a person is on an upward or downward trajectory.
I suspect that future scans will show that the bone density in your hips are not significantly different from one another, but the bone density is likely to decrease, since essentially all women in their late 60s and early 70s do lose bone density over time, unless they are taking active steps to prevent it. Regular walking and strength training slow down but do not usually stop bone loss. If the bone loss is sufficient to make a fracture likely, you will be recommended additional treatments.
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Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.
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