FM lab ranges in pre-visit briefs: reference vs functional medicine targets

Open a LabCorp panel and every analyte comes with a reference range printed next to it. TSH 0.4 to 4.5. Vitamin D, 25-OH, greater than 20. Free T3, 2.0 to 4.4. Ferritin, 15 to 300.

Those ranges are useful, but they answer a specific question: where does this value sit relative to the population the lab used to define normal. That population is large and statistically defined, and it is often a population that walked into a lab because something was already wrong.

Functional medicine clinicians are usually asking a different question. That gap drives a lot of pre-visit brief design for outpatient FM practices.

What the two ranges are actually for

The lab-default range is a screening tool. Its job is to flag values that are clearly outside the distribution of the reference population. A TSH of 8.5 gets flagged. A TSH of 4.2 does not, because 4.2 is inside the lab’s printed range, even when the patient feels cold and tired and has been gaining weight.

The FM target range is a clinical-management tool. Its job is to define where a patient should sit to feel and function well. It is narrower, and FM physicians have refined it over years of watching what actually lines up with outcomes.

Neither range is wrong. They answer different questions.

A handful of worked examples

A few analytes where the two ranges diverge most:

• TSH. Lab-default: 0.4 to 4.5 mIU/L. FM target: 0.5 to 2.0. A TSH of 4.2 is “in range” by the lab’s print but well above where most FM physicians want their thyroid-treated patients to sit.
• Vitamin D, 25-OH. Lab-default: greater than 20 ng/mL. FM target: 50 to 80. A patient at 28 is “sufficient” by lab default and undertreated by FM target.
• Free T3. Lab-default: 2.0 to 4.4 pg/mL. FM target: 3.2 to 4.2. A Free T3 at 2.4 is “normal” by the lab and at the bottom of the FM working window.
• Ferritin (women). Lab-default: 15 to 300 ng/mL. FM target: 70 to 150. A ferritin of 22 is “in range” by lab default and well below where most FM physicians want it for energy, hair, and exercise tolerance.

There are more (fasting insulin, hs-CRP, magnesium RBC, homocysteine, the rest of the thyroid panel). The pattern holds: the lab-default range is wide enough to miss most of what an FM physician is treating.

How the pre-visit brief shows both ranges

Every row in a Helose-assembled lab panel carries two range badges. One is the lab-default range, exactly as the lab printed it. The other is the FM target range, drawn from the clinic’s own configured profile.

By default, the brief shows the FM target. So a TSH of 4.2 shows up as “above target” with the FM range visible, and the lab-default range is one click away if the physician wants it. The doctor never loses access to the original lab reference. It is just not the primary frame.

A few specifics about how this works in practice.

The clinic’s target ranges are configurable. Different FM practices have different preferences. A Hashimoto’s-focused clinic and a metabolic-focused clinic might pick slightly different TSH targets, and both should be able to set their own without filing a ticket.

The badge is stateless. Helose does not say “this is concerning” or “this needs follow-up.” It says “above target,” “below target,” or “within target,” with the two ranges visible. What to do about it is the physician’s call.

The lab source is always shown. A Free T3 from a Genova panel and a Free T3 from LabCorp are on different assays, and a careful FM physician will want to know which assay produced the number before comparing it to a value from six months ago. The badge does not paper over the assay difference. It just adds the second frame of reference.

The target range applies in the brief summary view and the full portfolio view. It is not a chart-wide toggle. It is a persistent annotation on every analyte that has an FM target configured.

Why this isn’t a complaint about labs

Lab reference ranges are doing the job they were built for. They are a population-level screening tool, calibrated for a population-level question. Using them as a clinical-management tool is a clinician’s choice, and FM physicians made that call a long time ago when the lab’s frame was not the right one for their patients.

What Helose does is small. It carries both frames in the chart so the FM physician does not have to mentally re-anchor every value to a different range. The brief reads the way an FM physician already reads a panel: clinically meaningful target visible by default, population-level range available when it is useful.

This is not about saying labs are wrong. It is about meeting FM physicians where they already work, in the pre-visit brief and the patient portfolio that also powers between-visit patient texting for supplement and lab follow-through.

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