The dictionary defines the word “normal” as conforming to the usual standard, type or custom. Physicians are accustomed to getting laboratory values in terms of normal or abnormal, inferring that all normal results are good (there is nothing to worry about) and all abnormal ones are cause for alarm and concern. In truth, the answer is truly neither—changes in values are the most worrisome—both in clinical medicine and in underwriting.
Ranges of normal are broad enough to account for the diversity in people and what constitutes reasonable ranges of health. However, there is no rule of thumb for whether a higher normal is a good or bad circumstance. Too much of a measurable substance can be as dangerous to health as too little. When the values are outside the accepted range, the significance is easily grasped. More problematic is when a value in the normal range can indicate a substantial problem.
Let’s consider a CBC, or a complete blood count, as an example. Hemoglobin, measuring oxygen carried by the blood to tissues, is generally in the range of 14 to 16g/dL for a man and 12 to 14 for a female. Larger men can have higher numbers without being abnormal, while both men and women can have ethnic traits that make the values measure lower despite being healthy as well. The change in values is important. For example, a man with fatigue whose value was 16 before and is 14 now may be losing blood and could have a lesion or even cancer, despite having two values that are in the normal range. In such a case, using an attending physician statement with previous values for comparison is more helpful than the absolute measurement itself.
PSA (prostate specific antigen) values in men are another example. Every male has a measurable amount of this in his system. It is an enzyme that rises as the prostate enlarges with age, but also significantly when there is prostate cancer. Normal range is generally up to 4ng/mL, and slightly more in older males. A level of 6 can be “normal” if a man has a benign enlarged prostate and there is no disease. A normal value of 3.8 can be quite abnormal, especially if the value previous to that was 1.6ng/mL. In that case, the rise may be due to a growing prostate cancer that needs urgent evaluation. Even the normal value in this case is quite abnormal; more so than the previous example where the value was out of range but stable.
The differences can also be used to follow treated conditions. Let’s use the above example again but apply it to a prostate cancer situation where the cancer was treated and the PSA dropped well into the normal range. In fact, after a year or two the level was barely measurable, but two years later, when an insurance profile is done, the PSA rises from .004 to 1.0. While the value of 1.0 is still well within the normal range and, in fact, is low normal, the increase in this case would be indicative that cancer has returned and that the situation is far from optimal. Thus, the difference is far more important than the absolute value.
In a way, the definition of normal is more like the usual state of affairs or conditions for a situation; in fact, normal measures the range of values that are generally seen in people of good health. There are many situations where a high or low value out of this range is not cause for alarm. Rather the change in value from one level to another without an explanation is what is truly not normal and must be considered.
