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Digital Subscriptions > Skeptical Inquirer > May June 2019 > Too Many Medical Tests

Too Many Medical Tests

Harriet Hall, MD, also known as “The SkepDoc,” is a retired family physician, a CSI fellow, and an editor of the Science-Based Medicine blog. Her website is

Doctors order too many tests. Some are useless, some are harmless (except for the cost), but some can lead to serious bodily harm.

Misconceptions about Tests

Many people, including doctors, tend to think of tests as giving consistent and reliable yes or no answers. They think a test can make a diagnosis, but that’s not how it works. It’s much more complicated than that. Medical history and physical examinations are more important; tests only contribute around 10 percent to the diagnostic process. Misconceptions about tests abound. Here are some examples.

MYTH: A normal lab value is the same everywhere.

Reality: Different labs have different normal reference ranges. The Cleveland Clinic website defines a normal hemoglobin for a man as 14–18 grams per deciliter and for a woman, 12–16 grams per deciliter. Another website defines normal as 13.5–17 and 12–15. And the lab at Madigan Army Medical Center, where I get my medical care, has a reference range of 10.0–15.0, sex not specified. Normal reference ranges are different for children and pregnant women and may differ slightly for different racial groups. The source of the sample matters: blood from a fingerstick, for example, will give a higher cholesterol reading than blood from a vein.

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