Functional vs Normal Lab Ranges

Have you ever had your blood work come back totally normal despite not feeling well?

I see this a lot and I think much of it has to do with using normal lab ranges vs. functional ranges.

What Are “Normal” Ranges Based Off Of?
The reference ranges for different markers can vary from lab to lab, but most are defined as the set of values 95 percent of the normal population falls within. You can have both healthy and unhealthy individuals fall within the normal reference ranges for the same lab. This makes sense since reference ranges are often large and a lot can vary when you start getting to the low or high end of them. It’s also common to be in the early stages of dysfunction in the body and still have “normal” lab values.

What Are Functional Lab Ranges?
Functional lab ranges are based on levels that show organ systems are functioning optimally or nutrient stores are replenished. They are a great way to identify the early stages of dysfunction before things get too out of hand and a full-blown disease state is present.

Similar to how normal lab ranges vary based on the lab, functional lab ranges can vary based on the practitioner and their training and clinical experience.

Scroll above for a client example of normal vs. functional lab ranges with a previous client of mine named Sara. She struggled with her cycle, energy, and hair loss. After we monitored her basal body temperature and saw that she was consistently below 97F, I mentioned that’s a common sign of a sluggish thyroid. She asked her doctor to test her thyroid and was shocked to see it in range. Turns out, it was out of the functional range. This led to further testing and allowed us to focus in on supporting her thyroid.

I compiled functional blood lab ranges for over 50 blood labs and put them in a reference guide that is currently available to my Patreon patrons, sign up here!

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Amanda Montalvo

Amanda Montalvo is a women's health dietitian who helps women find the root cause of hormone imbalances and regain healthy menstrual cycles.

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