In Pursuit of Reference Ranges

In Pursuit of Reference Ranges

Joy Stepinski, MSN, RN-BC

January 3, 2025

Reference ranges are important tools for clinicians to use to compare a patient’s test results against a certain standard and guide decisions [1]. As described in the book Overdiagnosed: Making People Sick in the Pursuit of Health [2] the authors write that the numerical values “typically involve a single number: if you fall on one side of the number you are defined as well; if you’re on the other, you are defined as abnormal” [p.15]. Often, these numbers distinguish health from disease.

Our healthcare system focuses on prevention, which is synonymous with early detection. (More on this topic at another time.) By recognizing conditions early, people can receive timely treatment. As a result, professional organizations have changed the reference range values so that the thresholds detect potential diseases earlier [3]. The definitions have been changed for conditions such as high blood pressure, high cholesterol, and obesity.

One example found in the literature is diabetes. In past years, a blood sugar ≥140 mg/dL7 would show concern for the condition. However, the American Diabetes Association changed the definition and lowered the threshold from 140 to 126 mg/dL7. This created a higher prevalence of diabetes and 1.7 million new diagnoses of the disease!

The ramifications are many. Although a patient may benefit from early detection, other implications are pertinent. Studies show that all-cause mortality may not be any different. With more disease, healthcare providers have less time with patients. Diagnosis can potentially cause harm with unwanted medication side effects and disease labeling.

As you can see, the benefits of changing reference ranges are not necessarily clear-cut. Diagnosing people with a disease who are likely at low risk and receiving treatment that could possibly harm them is not beneficial to health. Awareness is key! In another article, we will discuss what you, as a patient, can do.

References:

1.       Friedberg, R. C., Souers, R., Wagar, E. A., Stankovic, A. K., & Valenstein, P. N. (2007). The origin of reference intervals: a College of American Pathologists Q-Probes study of “normal ranges” used in 163 clinical laboratories. Archives of Pathology & Laboratory Medicine, 131(3), 348-357.

2.      Welch, H. G., Schwartz, L., & Woloshin, S. (2012). Overdiagnosed: Making people sick in the pursuit of health. Beacon Press.

3.      Schwartz, L. M., & Woloshin, S. (1999). Changing disease definitions: Implications for disease prevalence. Analysis of the Third National Health and Nutrition Examination Survey, 1988-1994. Effective Clinical Practice, 2(2), 76 – 85.