Why We Order Redux Lab Tests


George D. Lundberg, MD

In 2022, doctors have a wide range of clinical laboratory tests – and other diagnostic tests – to choose from. What tests should we order and why?

Lab tests should not be ordered before or unless the doctor knows how the results will be used and has a plan of action. Many lab tests do not need to be performed at all; results are negative, normal, or show no change from previous tests.

In 1979, we asked staff at Los Angeles County Medical Center/University of Southern California to respond to a large survey of why they ordered specific lab tests.

The reasons?

  • 37% of tests were ordered for diagnosis;

  • 33% for screening;

  • 32% for monitoring;

  • 12% for a previous abnormal result;

  • 7% for prognosis;

  • 2% for education; and

  • 1% for medical-legal concerns.

I consider these reasons “basic” and have followed them with multiple Socratic requests from lab assemblies in many states and countries to categorize the reasons doctors order lab tests:

  • Good: to confirm a clinical opinion; question of the accuracy of the previous result; unavailability of the previous result; state legal requirement; personal education; to research; and show to a attending physician.

  • Neutral: peer pressure ; patient pressure; family pressure; personal education; hospital policy; concern for responsibility; establish a baseline; curiosity; personal insurance; Documentation; and pressure from recent literature.

  • Wrong: personal or collective benefits; benefit of the hospital; fraud, bribes; CYA; hunting or fishing expeditions; standing orders for daily monitoring; complete a database; public relations; insecure; frustration of not doing anything better (I don’t know what’s wrong with this patient, better get lab tests); to save time (maybe by the time the lab tests come back I’ll have better ideas of what’s wrong with this patient); uncomplicated availability; and ease of doing.

  • Ugly: I refer you to the 35 things not to do from the American Society for Clinical Pathology section of ABIM’s Choose Wisely campaign. For example, do not use the bleeding time test; do not use ESR (sedimentation rate).

Now for a new reason

A helpful placebo effect may be experienced by the patient (and possibly the physician) upon receipt of a negative or normal lab test result. Worry relieved.

Imagine that you are middle-aged and suffer from a chronic cough that you have attributed to an allergy and post-nasal drip. You have never smoked, but many patients with lung adenocarcinoma are non-smokers. Your primary care physician, in accordance with revised guidelines, ceased routine annual chest X-rays many years ago. But now she orders a chest X-ray. It’s normal, don’t worry. It is really good.

Pap smear in a 40-year-old multiparous woman with vaginal discharge. Negative. Great.

Runny nose, itchy throat, a little discomfort. Two negative COVID tests. Yes!

History of hypertension, on antihypertensives; blood pressure 115/78. Tremendous.

Lost 20 pounds intentionally; resting heart rate 61. Outstanding.

Saw my dentist, asymptomatic, annual exam. No cavities. Splendid.

Mounted on the scale, body mass index 21. Excellent.

If I am 65, have no prostate symptoms, but my father and two brothers died of prostate cancer, I would like a prostate specific antigen (PSA) test. Results: 1.2 ng/mL. Hip, hip, hooray!

Of course, rational periodicity is key. My Fitbit gives me my heart rate 24/7. I don’t need hourly public service announcements or daily visits to the dentist. I mean, how much can a person tolerate a happy placebo rush?

It’s my opinion. I’m Dr. George Lundberg, free for Medscape.

George Lundberg, MD, is editor-in-chief of Cancer Commons, president of the Lundberg Institute, executive advisor to Cureus, and clinical professor of pathology at Northwestern University. Previously, he served as editor of JAMA (including 10 peer-reviewed journals), American Medical News, and Medscape.

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