Normal Isn't Always Good Enough

Posted by Jennie Ann Freiman MD on

“Normal” is often not good enough, especially when it comes to health. We consider something “normal” if it’s an accurate statistical representation of a given outcome. In the case of standard laboratory testing, generally normal results do not necessarily equate to optimal outcome for the individual. Until personalized medicine (tailoring diagnosis and treatment to each patient) is fully realized, it makes sense to scrutinize current laboratory reference ranges defined as “normal.” Frequently, we can do better.

These are three important examples of tests whose normal results are linked to specific (avoidable) disease states:

Thyroid health: Thyroid-stimulating hormone (TSH) is the standard screening test for assessing thyroid function. Most laboratories (and doctors) accept a range of 0.4-5.5mIU/L as normal, despite overwhelming evidence that adverse health outcomes are linked to TSH above 2.0, even when thyroid hormones (T3 and T4) are normal. Health conditions associated with a TSH in the upper half of normal include an increase in blood lipids, cardiovascular disease and mortality, fracture (and low bone mineral density, especially in post-menopausal women), male and female infertility, complications of pregnancy (miscarriage, preterm labor), mood disorders, dementia, and autoimmune thyroiditis (Hashimoto’s disease). Experts have known about the increase risks of high-normal TSH for over two decades, but so far this awareness hasn’t led to a revised consensus for diagnosis and treatment. One recent recommendation for evaluating thyroid disease involves screening with a combination of TSH, free T3 and T4, and consideration of the individual’s clinical status. Redrawing the lines of “normal” to the narrower 0.4-2.0 mIU/L range for TSH would cause millions of Americans to suddenly be diagnosed as hypothyroid, creating an unwelcome burden for insurance companies.

Vitamin D3: Vitamin D plays an important role in both skeletal and non-skeletal health. Public health recommendations for sun-avoidance, successful in protecting against skin cancer, contributed to epidemic levels of vitamin D deficiency in the general population. The lower end of the common laboratory “normal” range of 20-50ng/mL is not optimal. Insufficient vitamin D3 is associated with an increase in fracture, cancer, and cardiovascular, autoimmune and neurodegenerative disorders. The Vitamin D Council recommends 50ng/mL as the ideal level. Prudent sun exposure and vitamin D intake by diet and/or supplements to reach this level is strongly recommended. Note: Levels of vitamin D above 100ng/mL are too high and pose health risks.

Homocysteine And Vitamin B12: Homocysteine is commonly tested as a marker for cardiovascular health but its relationship to cognitive impairment and Alzheimer’s disease should be considered in assessing normal reference ranges. Homocysteine reflects the status of vitamins B12, B6 and folate, all of which are key to optimizing mental function. The normal range for homocysteine in women is <10.4 umol/L and in men, <11.4 umol/L. Clinical studies find that homocysteine levels at the high end of normal are linked to a 1.15 to 2.5 relative risk for dementia. Optimal homocysteine is less than 7.2 umol/L. Similarly, normal vitamin B12 levels of 200-1100pg/mL are associated with dementia at the lower end of 200-400pg/mL. Homocysteine, B12, B6 and folate can be improved by diet and supplements.

Optimizing health is the best insurance policy for resilience against disease. Take steps that make a difference.


Disclaimer: This article was created for informational purposes only, is not intended to provide medical advice, diagnosis or treatment and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Views expressed here do not necessarily reflect those of Oobroo™ Inc or its staff.

References available on request: email


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