Here's when you should ask your doctor for medical tests

Unnecessary testing can be wasteful and dangerous, and it doesn't always mean an improvement to health.
By Dr. Danielle Martin
Illustration, Casey Wilson. Illustration, Casie Wilson.

Q: I always worry that I’ll be diagnosed with an illness that could have been caught earlier. Now that I’m over 40, should I be asking for more tests?

Whenever someone raises this issue, I think about the woman in my practice who requested a “baseline” mammogram even though she was in her early 40s with no family history of breast cancer. The test is currently recommended for women over the age of 50 who are at average risk — but she wanted to be proactive about her health.

Women in their early 40s tend to have dense breasts, which can lead to more shadows showing up on mammograms that, while not significant, compel a follow-up. In my patient’s case, she was called back for more imaging sessions (involving radiation) for a finding that was essentially normal for a woman of her age. She did not have breast cancer  — but for 18 months, she was subjected to unnecessary and potentially harmful tests, and all the stress that came with it.

Now, what if the mammogram had picked up something important? Would the risks be worth it? I’d argue we need to weigh what good can come of testing (without explicit cause) against its potential dangers.


Millions of Canadians every year are subjected to inappropriate, wasteful and harmful tests. In addition to the chances of false positives, there is the risk of over-diagnosis, where we identify harmless abnormalities that we may then feel compelled to treat. And testing doesn’t go hand in hand with improvements in health. For example, the Canadian Association of Radiologists has estimated that as many as 30 percent of imaging studies contribute no useful information, yet the harm can be substantial: It’s estimated that some 14,000 cancer deaths each year in the U.S. could be attributed to excessive exposure to radiation from CT scans.

The rise of over-testing can be linked to the influence of industry, fear of litigation and changing patient expectations. It can be hard, for instance, for my patients to feel secure with my recommendation to hold off on bone-density tests until age 65, when their friends’ doctors are ordering them at 50 .

A campaign to raise awareness about this issue, called Choosing Wisely Canada, is a great resource. It suggests that the next time you approach your doctor about a test, you should also ask, “Do I really need this?” “What are the downsides?” “Are there simpler, safer options?” And last, but important, “What happens if I do nothing?”

Doctor. Danielle Martin, Chatelaine columnistDanielle Martin is a family physician and vice-president, medical affairs and health system solutions, at Women’s College Hospital in Toronto.


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