Why “Normal” Blood Labs May be Steering You in the Wrong Direction

For patients, deciphering laboratory values can be an arduous process. It is easy to become focused on the “normal” range provided along with the results. These are calculations used to guide treatment, but should not be taken as absolute truth or the only way to achieve optimum health for you. I would like to discuss many important components to laboratory values and what they mean for you.

Laboratory norms have been established by averages among individuals generally perceived to be healthy. These are statistical calculations. As we all know, statistics can be widely variable. In fact, different laboratory companies will establish different ranges for normal. The specific statistical calculation that is generally used requires taking a group of one hundred twenty healthy individuals from a specific region of the population. Often this does not account for variations based upon age, gender, race or demographic difference. The values taken from these selected individuals are then analyzed and a range is created for the mean 95% percent. This would leave 2.5% above the range considered “normal” and 2.5 % below that are accepted to have no disease process. There has been some debate about increasing this to a 99.9%, however, there would a greater number of missed abnormalities with this. It generally accepted by the medical community to have an increased attention to abnormalities, even if it results in unnecessary testing, versus missing a disease process.

Secondly, lab values can be influenced by technique used to transport lab specimens, time lapse for processing specimens, and reagents or equipment used in the laboratory. Calibration of the machines must be preformed regularly for the results to be accurate.

Each individual will have a number of variables that can influence laboratory values without a disease abnormality. These include: time of lab draw, diet, exercise, stress, timing of influencing medications, sleep, sexual activity and hydration.

When considering all these factors, recommendations for consistency from one lab draw to the next would be scheduling at the same time of day (first thing in the morning is best), the same day in your dosing cycle (the day prior to administration of testosterone if on IM injections/no application of hormone cream the morning of the draw), fasting for at least 8 hours, full 8 oz glass of plain water the morning prior to the lab draw, and no sexual activity for 48 hours prior. Women should coordinate with day 19-21 of her cycle if she is still menstruates.

For those who would like the details as to why each of these factors is important, I will outline them for you.

  1. Fasting draw is important to assess glucose level and cholesterol panel.
  2. The same day of your dosing cycle will eliminate spikes in values due to supplemented hormones.
  3. Full glass of water will ensure you are hydrated adequately which will given a more accurate picture of kidney function and hemoglobin and hematocrit.
  4. No sexual activity is important for men in association with PSA levels. Ejaculation causes a spike in PSA, which will general return to normal approximately 36 hours after activity. We would not want to get the idea your PSA was elevated unnecessarily.
  5. Women will be more complicated if she is still cycling as there is a large range in the hormones depending on the day of the cycle.

The key take away point being laboratory values should be correlated with clinical symptoms. The ideal levels for one individual may not achieve optimum results in another. This is exactly why you and your provider will work together and make adjustments based on exact goals. For example, we know that homocysteine normal levels on a typical blood lab panel range from 0.0 to 15.0 umol/L. However, we also know that 6-7 umol/L is optimal with the risk for CVD rising 20%-30% for each 5- point rise above that optimal level. Thus, if you are at a 15.0 umol/L, you have roughly a 50% greater risk of cardiovascular disease than if you were at a 6.0 umol/L…but yet, you are still in the “normal” range. This is one more reason why you place great faith in your health care provider to not only know all the science behind the true optimal levels of blood labs, but also have the patience and skill to accurately associate that knowledge with your specific situation.

Dr. Smellier wrote in the Journal of Clinical Pathology, “We can improve information about factors that influence reference ranges, highlight results that are more likely to be clinically relevant than others, and inform users and patients about the limitations of normal ranges, but tests must ultimately remain a supporting piece of evidence in a clinical context.” 1

This should provide reassurance that slightly abnormal test results should not be a cause for concern. They are a snapshot of what is going on in your body at an exact moment. They should be used as a guide to steer treatment plans. Collaborating and communicating with your provider and watchful monitoring of these levels will very often result in a unified approach to finding the right balance. Together, we can decide what “normal” means to you.


  1. Smellie, W. S. A. When is “abnormal” abnormal? Dealing with the slightly out of range laboratory result. Journal of Clinical Pathology. 2006 Oct; 59(10): 1005–1007.

doi:  10.1136/jcp.2005.035048

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