Lab explainer
Normal vs Optimal: Lab Range Explainer
A result inside the normal range is not always the whole story. Enter the numbers from your lab report to see three ranges side by side: the range your lab printed, the published medical guideline, and the target Dr. Samia McCully, ND uses in her practice. It also works out HOMA-IR and the triglyceride to HDL ratio.
Reviewed October 24, 2026 · Free to use · Your answers stay on this device
- 11common lab markers
- 3ranges for each result
- 2ratios calculated for you
- 0results sent anywhere
Three Ranges, Three Different Questions
Each range answers a different question, which is why a result sometimes looks fine on one and not on another.
Lab range
Is this unusual?
The reference interval printed on your report covers the middle 95% of a tested population. It flags results that are statistically unusual, not results that are ideal.
Guideline
Is this a diagnosis?
Guideline cutoffs, such as an A1C of 6.5% for diabetes, come from studies that link values to disease. Medical societies publish and update them.
Clinician target
Is this where I feel and function well?
Some clinicians aim for a narrower target for an individual patient. These targets are clinical judgment, differ between clinicians, and are labeled as such here.
"Normal" Labs Still Have a Story
Patients often tell Dr. Samia McCully, ND that their labs came back normal and there is nothing to see. She looks anyway, and she finds things in normal labs. A ferritin that has fallen from 80 to 25 in two years tells a different story than a steady 25, even though both sit inside many labs' normal ranges.
Recent labs from the past two years help if you have them, but none are needed to book. Dr. McCully orders labs for any patient, often through insurance, as the guide on normal labs that still leave you feeling unwell explains.
Common Questions
What is the difference between a normal range and an optimal range?
A lab's normal range, or reference interval, covers the middle 95% of results from a group of people the lab tested, many of whom are not in good health. A guideline range comes from research linking values to outcomes such as diabetes or anemia. An optimal or target range is a clinician's choice for an individual patient, and clinicians differ on those targets.
Why does my lab's range differ from the one shown here?
Each lab sets its own reference interval for its equipment, methods and population, so ranges vary from lab to lab. Enter your lab's printed range in the optional boxes and the explainer uses it instead of the typical range.
Is a result outside the target range something to treat?
Not on its own. One number is a snapshot, and many results shift with recent meals, illness, exercise or the time of day. A clinician reads results together with symptoms, history and trends before recommending anything.
Why is cortisol not on the list?
Wellness Architecture does not offer cortisol testing. The explainer covers markers Dr. Samia McCully, ND reviews in her practice.
Sources and How This Tool Works
Guideline ranges come from the sources below: the National Academy of Medicine and the Endocrine Society for vitamin D, the American Gastroenterological Association and WHO for ferritin, the American Diabetes Association for glucose and A1C, the AHA and CDC statement for hs-CRP, the American College of Rheumatology for uric acid and the NIH Office of Dietary Supplements for vitamin B12. Typical lab ranges are approximate and vary by lab. HOMA-IR is fasting glucose (mg/dL) times fasting insulin (µIU/mL) divided by 405 (Matthews, 1985). Clinician targets are Dr. Samia McCully's own and are labeled as hers; they are not national guidelines. Unit conversions use standard factors. Everything runs in your browser.
- Endocrine Society. Vitamin D for the prevention of disease clinical practice guideline, 2024
- Institute of Medicine (National Academy of Medicine). Dietary Reference Intakes for Calcium and Vitamin D, 2011
- Ko CW et al. AGA clinical practice guidelines on the gastrointestinal evaluation of iron deficiency anemia. Gastroenterology, 2020
- American Diabetes Association. Standards of Care in Diabetes: Diagnosis and Classification
- Pearson TA et al. Markers of inflammation and cardiovascular disease, AHA/CDC scientific statement. Circulation, 2003
- Matthews DR et al. Homeostasis model assessment. Diabetologia, 1985
- FitzGerald JD et al. 2020 American College of Rheumatology guideline for the management of gout
- NIH Office of Dietary Supplements. Vitamin B12 fact sheet for health professionals
General health information, reviewed October 24, 2026. This tool informs; it does not diagnose, treat or replace care from a licensed clinician, and the linked sources' current versions control. Very low or very high blood sugar, and any result your lab flags as critical, need prompt attention from your doctor. If something feels urgent, call 911 or your doctor.
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