Your Blood Work, On The Edge Of Normal

“Variability is the law of life, and as no two faces are the same, so no two bodies are alike, and no two individuals react alike and behave alike under the abnormal conditions which we know as disease “William Osler.

Historically, medical decisions have relied heavily on clinical experience, expert opinions, and other subjective or uncontrolled sources of information. This had also been true in laboratory medicine, where often an inadequate foundation of evidence is found to support existing practices. There is no clear understanding of why a test is ordered or what clinical question it is trying to answer, what to do when routine test results are at the high or low end of acceptable range.

It is tricky, because in some tests, a borderline result makes no difference. In others, it might indicate an important change in health that we need to follow or act on.

About Normal Ranges:

Each lab establishes its own normal range for blood tests. This is based on various factors like makeup of the local population, instruments used to look at the samples and technologies used to separate various components in the blood.When you look at a print out of your lab results, you will find the normal ranges for each test next to your own values. For example: Your calcium is 9.1mg/dl and the normal range is 8.3 to 9.9mg/dl, you can feel confident that your calcium level is normal.

Interpreting The Numbers:

Blood tests can vary a little bit depending on the lab. So if the test result is very low or high end of normal, don’t jump to conclusions. For example: When we don’t drink enough water, BUN (Blood Urea Nitrogen) will go up. This can happen even during fasting. It does not always mean that the kidney function is declining.

Minor Fluctuation In The Test Results May Also Reflect:

• Recent infections
• Side effects of medication
• Stress
• Gender & age-related
• Inaccurate lab procedures

Hence the entire picture of the health of any individual should be looked at to interpret a blood test.

When Should You Be Concerned?

Always look at trends instead of looking at a one-time test result in the high or low end of normal. Be concerned only when there is a change from what’s been normal for years for you.

What Should You Do?

Get an annual check up and don’t skip the routine blood work. Even if you feel that you are healthy, it is still a good idea to have a continuous record of standard blood markers andlook for trends.In case there are worrisome results, repeat the test and investigate the cause if it is of concern.Keep watching your blood work. It is important to be proactive about maintaining good health. “Each test has its own rules, and it takes years to understand how the numbers work together”.

Conclusion:

Laboratory results must undergo a two-step post-analytic review for analytic correctness (using data checks, linearity range etc. and for clinical significance for the patient by applying critical values, reference ranges, pretest and post-test probability. Every result has to be assessed for analytic correctness and for clinical significance.So it is the combined effort of the performing laboratory, which is responsible for the determination of analytical correctness, and the clinical team, which is responsible for the evaluation of the clinical meaning of the results.