What patients are most concerned about when they get their labs is whether their test results are normal or not, in other words, whether they are within the normal range of values. First, let’s talk about this concept, which used to be called normal value, but is now changed to reference range. The patient’s test results are outside the reference range, is there necessarily a problem? The answer is no. What is the reference range? How is it developed? The reference range is a range developed statistically using a 95% confidence interval (normal distribution), which means that in a test, 95% of healthy people are within this reference range, and 5% of healthy people are outside the reference range, and these 5% of people are not necessarily patients. If one’s test results are outside the reference range, one must make sure to interpret them correctly in the context of the clinic. The reference range can be influenced by age, gender, weight, diet structure, activity status, body position, geographic and climatic conditions, lifestyle habits, occupation, race, etc. Therefore, it is important to understand the reference range correctly to avoid unnecessary psychological burden on the patient.