Your Health and the Bell Shaped Curve

How many of you have been to your doctor for review of routine blood work and have been told that it is all “fine” or “within normal limits”? Have you ever wondered how the “normal” values for labs are established and what it means to have normal values? Have you ever questioned whether normal values are optimal values that contribute to optimal health? What does it mean to be on the high end or low end of normal values? These are important questions to consider if your goal is optimal health. It will be easy to understand why when you understand how normal lab values are established.    

Lab values can vary from lab to lab, especially at different locations across the country. This is because normal lab values are established by averaging the values for the patients in a given area who have their blood work done over a given period of time. The numbers reflect a bell shaped curve with most of the patients falling in the middle of this. What is the problem with this? Chronic disease is rampant in the US; diabetes, heart disease, autoimmune diseases and cancer, among others are commonplace. Although healthy patients do occasionally go in for screening blood work, those with disease are having blood work done much more frequently. This means the “normal” lab values are skewed away from optimal values and closer to disease values. This is a simplified but accurate overview of how lab values are established. For optimal health, more than averages need to be looked at.

There are more reasons for taking a second look at “within normal limits.” Normal limits can be quite broad. Two good examples of this are ferritin and glucose (blood sugar). 

Ferritin is the protein that stores iron in your cells; it is a reserve for your body to draw on when you need it. Measuring ferritin is an indirect measurement of iron in your blood. The basics of anemia, a condition of too little iron, were covered in the previous post. Remember that iron helps carry oxygen around the body, it affects energy and it can also affect the menstrual cycle; if it is too low, women bleed more heavily creating a vicious cycle of iron loss through menses. “Normal” ranges from 12- 150 ng/mL in women and 12-300 ng/mL in men. This is a large range. Common sense tells you that you will feel different when your ferritin is 15 ng/mL than when it is 90 ng/mL, yet both are considered normal. If your ferritin level is 11 you are more likely to be treated than if your ferritin is 15. A ferritin of 15 ng/mL would benefit from treatment as well, especially if the patient is exhibiting symptoms of anemia. Lab values should always be taken in the context of each individual’s symptoms and overall picture.

The second example, blood sugar or fasting glucose, is how diabetes is diagnosed. A fasting glucose of 126 mg/mL or higher is considered diabetic and this is when treatment is typically initiated. Does this mean a fasting glucose level of 100 mg/mL is a good blood sugar that can be ignored? No. 100 mg/mL is not a healthy glucose level, it is just not considered to be a disease level yet. Optimal blood sugar levels run 70- 89 mg/mL. Anything above or below is likely a problem and needs to be addressed. Addressing a blood sugar level that is creeping towards diabetic or pre-diabetic is preventive medicine. There are many simple changes that can be made to your life and diet to address fasting blood sugars higher than 89. Blood sugar levels can contribute to many more diseases than just diabetes, including Alzheimer’s and metabolic syndrome. You will feel better by keeping levels at a healthy optimal value.

Optimal ranges exist for other lab values as well, including HDL and measurements of thyroid activity (THS, Free T3 and FreeT4). I look for optimal levels whenever I review lab work. This is because as a Naturopathic Doctor I seek to do more than address frank disease; I seek to help my patients prevent future disease and create the highest level of current health. To do this I also take in to consideration the individual and what is “normal” for them. Additionally, the whole of the blood work results, as well as physical exams, history, and, if necessary, additional testing need to be considered when assessing the significance of a single value. Using optimal lab values and context in this way is referred to as functional blood analysis. I strongly encourage you to have even your routine lab work reviewed by a practitioner trained to consider the results in these ways. This is likely to go a long way towards disease prevention and meeting your personal health goals. Be well.