Understanding the gap between normal and optimal gives you a different framework for interpreting your results and advocating for yourself in clinical settings. It does not mean every borderline-normal result requires aggressive intervention. It means asking your physician what your actual number is, not just whether you passed or failed the range. It means understanding which direction your markers are trending. And it means recognising when your symptoms are providing information that your labs are not capturing.
A registered dietitian working in this space can interpret your results in nutritional context — identifying which markers suggest dietary gaps, which suggest metabolic shifts that respond to nutritional intervention, and which require medical co-management. Nutrition cannot and should not replace medical investigation. But it sits at the intersection of almost every metabolic, hormonal, and inflammatory marker discussed here, and it is where many of the most meaningful and modifiable levers are found.
You deserve results that are interpreted in the context of your age, your hormonal phase, your symptoms, and your health goals — not just held up against a reference range built for someone else. That is the standard of care you should expect, and it is worth advocating for. The first step is understanding that normal and optimal are different questions, and that the gap between them, in perimenopause, is where much of your experience lives. Closing that gap is possible, measurable, and worth pursuing with the right clinical support behind you. It begins with a single conversation with your physician in which you arrive informed, ask specific questions, and request the numbers behind the normal stamp. That conversation alone can change everything that follows.
📞 If you have received normal lab results but still feel like something is off, your instincts may be right. At The Menopause Dietitians, we look at bloodwork in nutritional and hormonal context — not just whether the numbers clear a threshold. Click the button below to book your free 20-minute Menopause Strategy Call.
A registered dietitian working in this space can interpret your results in nutritional context — identifying which markers suggest dietary gaps, which suggest metabolic shifts that respond to nutritional intervention, and which require medical co-management. Nutrition cannot and should not replace medical investigation. But it sits at the intersection of almost every metabolic, hormonal, and inflammatory marker discussed here, and it is where many of the most meaningful and modifiable levers are found.
You deserve results that are interpreted in the context of your age, your hormonal phase, your symptoms, and your health goals — not just held up against a reference range built for someone else. That is the standard of care you should expect, and it is worth advocating for. The first step is understanding that normal and optimal are different questions, and that the gap between them, in perimenopause, is where much of your experience lives. Closing that gap is possible, measurable, and worth pursuing with the right clinical support behind you. It begins with a single conversation with your physician in which you arrive informed, ask specific questions, and request the numbers behind the normal stamp. That conversation alone can change everything that follows.
📞 If you have received normal lab results but still feel like something is off, your instincts may be right. At The Menopause Dietitians, we look at bloodwork in nutritional and hormonal context — not just whether the numbers clear a threshold. Click the button below to book your free 20-minute Menopause Strategy Call.
What to Do With This Information
Fasting glucose above 7.0 mmol/L indicates diabetes. Pre-diabetes is defined as fasting glucose between 6.1 and 6.9 mmol/L. A result of 5.9 mmol/L is technically normal. But the progression from normal fasting glucose to pre-diabetes to type 2 diabetes is not a sudden cliff — it is a gradual continuum, and fasting glucose is a late marker that shifts only after insulin resistance has been present for some time.
Fasting insulin, as discussed in the companion post on bloodwork, is the more sensitive early marker. But within glucose itself, tracking the trend over time matters. A woman whose fasting glucose was 4.8 mmol/L five years ago and is now 5.7 mmol/L has a result that is still normal — but the direction of travel is worth noting and acting on nutritionally, not waiting for the number to cross a threshold before intervening.
The same applies to HbA1c (glycated haemoglobin), which measures average blood glucose over 8 to 12 weeks. An HbA1c of 5.5 percent is normal. An HbA1c of 5.8 percent is still normal, but is classified as elevated normal in some guidelines and is associated with meaningfully higher risk of progressing to pre-diabetes. In perimenopause, where insulin sensitivity is declining and central fat accumulation is increasing, tracking the direction of these markers — not just whether they clear the threshold — is the clinically useful approach.
Fasting insulin, as discussed in the companion post on bloodwork, is the more sensitive early marker. But within glucose itself, tracking the trend over time matters. A woman whose fasting glucose was 4.8 mmol/L five years ago and is now 5.7 mmol/L has a result that is still normal — but the direction of travel is worth noting and acting on nutritionally, not waiting for the number to cross a threshold before intervening.
The same applies to HbA1c (glycated haemoglobin), which measures average blood glucose over 8 to 12 weeks. An HbA1c of 5.5 percent is normal. An HbA1c of 5.8 percent is still normal, but is classified as elevated normal in some guidelines and is associated with meaningfully higher risk of progressing to pre-diabetes. In perimenopause, where insulin sensitivity is declining and central fat accumulation is increasing, tracking the direction of these markers — not just whether they clear the threshold — is the clinically useful approach.
Fasting Glucose: Normal Today, Pre-Diabetic Tomorrow
The vitamin D sufficiency cutoff used by most labs — 50 nanomoles per litre — was set based on the level needed to prevent rickets and severe bone disease. It is not the level at which vitamin D's broader effects — immune modulation, mood regulation, muscle function, cardiovascular protection, and cancer risk reduction — are optimised. Multiple large studies and meta-analyses place the functional optimum for these outcomes in the range of 100 to 150 nmol/L.
A woman with a vitamin D level of 60 nmol/L will be told she is sufficient. She is, in the sense that she is unlikely to develop rickets. But she is operating with a vitamin D level that many researchers consider suboptimal for the outcomes most relevant to her health in menopause — bone density maintenance, reduced inflammatory burden, and immune regulation. Given that vitamin D supplementation is safe, inexpensive, and widely available, knowing your specific level and targeting an optimal range rather than simply clearing the sufficiency threshold is a straightforward and high-value intervention.
A woman with a vitamin D level of 60 nmol/L will be told she is sufficient. She is, in the sense that she is unlikely to develop rickets. But she is operating with a vitamin D level that many researchers consider suboptimal for the outcomes most relevant to her health in menopause — bone density maintenance, reduced inflammatory burden, and immune regulation. Given that vitamin D supplementation is safe, inexpensive, and widely available, knowing your specific level and targeting an optimal range rather than simply clearing the sufficiency threshold is a straightforward and high-value intervention.
TSH: The Range That Misses Functional Hypothyroidism
The TSH (thyroid-stimulating hormone) reference range used by most labs runs from approximately 0.4 to 4.5 milli-international units per litre. A result of 4.0 mIU/L is technically normal. But research — and the clinical experience of practitioners who work closely with thyroid patients — suggests that many people feel symptomatic at TSH levels above 2.0 to 2.5 mIU/L, particularly women. The American Thyroid Association has previously suggested that a TSH above 2.5 mIU/L may warrant monitoring and intervention in certain populations.
In perimenopause, where thyroid symptoms and menopause symptoms overlap significantly — fatigue, weight gain, brain fog, hair thinning, mood disruption, constipation — a TSH of 3.5 mIU/L sits comfortably within the normal range while potentially contributing meaningfully to the symptom picture. Ordering free T3 and free T4 alongside TSH, and comparing the full picture to symptoms rather than just the reference range cutoff, provides considerably more clinical information.
The functional TSH conversation to have with your doctor:
In perimenopause, where thyroid symptoms and menopause symptoms overlap significantly — fatigue, weight gain, brain fog, hair thinning, mood disruption, constipation — a TSH of 3.5 mIU/L sits comfortably within the normal range while potentially contributing meaningfully to the symptom picture. Ordering free T3 and free T4 alongside TSH, and comparing the full picture to symptoms rather than just the reference range cutoff, provides considerably more clinical information.
The functional TSH conversation to have with your doctor:
- Standard range: 0.4 to 4.5 mIU/L
- Functional optimum often cited: 1.0 to 2.0 mIU/L for symptom-free function
- Worth discussing: free T3 and T4 alongside TSH, especially if symptoms are present
- Also worth checking: thyroid antibodies if autoimmune thyroid disease is suspected
Vitamin D: Sufficient Is Not the Same as Optimal
Standard ferritin ranges at most Canadian and American labs run from approximately 10 to 200 ng/mL for adult women. A result of 15 ng/mL is within range. A result of 25 ng/mL is well within range. But at these levels, iron stores are significantly depleted relative to what the body needs for optimal function. Ferritin is the storage form of iron — when dietary iron intake is insufficient over time, the body draws on ferritin to keep circulating iron adequate, and ferritin falls before any other iron marker does.
The functional threshold most commonly cited in functional medicine and nutrition research is 50 ng/mL as a minimum, with 70 to 100 ng/mL as optimal for resolution of symptoms like fatigue and hair loss. A woman with ferritin at 20 ng/mL who is told her iron is normal may spend years experiencing the consequences of iron depletion — hair thinning, exhaustion, poor concentration, cold hands and feet — without anyone connecting the result to her symptoms, because the lab flagged nothing.
This is compounded in perimenopause by the fact that heavy or irregular bleeding is common and directly drives iron loss. A woman losing more blood each cycle while eating the same dietary iron she always has is in a negative iron balance, and standard screening will not catch it until it has become significant.
Functional ferritin targets:
Below 30 ng/mL: iron depletion — symptoms likely regardless of other markers
30 to 50 ng/mL: low-normal — may be sufficient but warrants monitoring and dietary support
50 to 100 ng/mL: functional optimum — where most women feel and function best
Above 200 ng/mL: warrants investigation for inflammation or haemochromatosis
The functional threshold most commonly cited in functional medicine and nutrition research is 50 ng/mL as a minimum, with 70 to 100 ng/mL as optimal for resolution of symptoms like fatigue and hair loss. A woman with ferritin at 20 ng/mL who is told her iron is normal may spend years experiencing the consequences of iron depletion — hair thinning, exhaustion, poor concentration, cold hands and feet — without anyone connecting the result to her symptoms, because the lab flagged nothing.
This is compounded in perimenopause by the fact that heavy or irregular bleeding is common and directly drives iron loss. A woman losing more blood each cycle while eating the same dietary iron she always has is in a negative iron balance, and standard screening will not catch it until it has become significant.
Functional ferritin targets:
Below 30 ng/mL: iron depletion — symptoms likely regardless of other markers
30 to 50 ng/mL: low-normal — may be sufficient but warrants monitoring and dietary support
50 to 100 ng/mL: functional optimum — where most women feel and function best
Above 200 ng/mL: warrants investigation for inflammation or haemochromatosis
Ferritin: The Normal Range That Misses Iron Depletion
Reference ranges are derived from population studies, and those populations are not always representative of the person in the chair. Most standard ranges were established with a general adult population that includes men and premenopausal women. They were not designed to identify the functional thresholds relevant to perimenopausal and postmenopausal women experiencing accelerated shifts in bone density, metabolic function, cardiovascular risk, and cognitive health.
When you have your ferritin tested, for example, the lower limit of the reference range at most labs is somewhere between 10 and 20 nanograms per millilitre. A result of 22 ng/mL will come back labelled normal. But research consistently shows that ferritin below 30 ng/mL — and particularly below 50 ng/mL — is associated with fatigue, hair loss, impaired cognitive function, reduced exercise tolerance, and mood disturbance. The reference range was not built to detect optimal iron sufficiency. It was built to detect anaemia. Those are very different clinical questions.
The same principle applies across multiple markers. Vitamin D, fasting insulin, TSH, blood glucose — in each case, there is a meaningful gap between the level at which a lab flags a result as abnormal and the level at which research supports optimal function. In perimenopause, where the consequences of nutrient insufficiency and metabolic dysfunction compound quickly, operating in the lower half of the normal range is often not the same as thriving.
Key takeaways:
When you have your ferritin tested, for example, the lower limit of the reference range at most labs is somewhere between 10 and 20 nanograms per millilitre. A result of 22 ng/mL will come back labelled normal. But research consistently shows that ferritin below 30 ng/mL — and particularly below 50 ng/mL — is associated with fatigue, hair loss, impaired cognitive function, reduced exercise tolerance, and mood disturbance. The reference range was not built to detect optimal iron sufficiency. It was built to detect anaemia. Those are very different clinical questions.
The same principle applies across multiple markers. Vitamin D, fasting insulin, TSH, blood glucose — in each case, there is a meaningful gap between the level at which a lab flags a result as abnormal and the level at which research supports optimal function. In perimenopause, where the consequences of nutrient insufficiency and metabolic dysfunction compound quickly, operating in the lower half of the normal range is often not the same as thriving.
Key takeaways:
- Reference ranges define the middle 95% of a population — not optimal health for an individual.
- Ranges were often built from studies not designed around perimenopausal women.
- A result can be technically normal and still be clinically meaningful, particularly in the context of symptoms.
How Reference Ranges Are Built — and Why That Matters
Your lab results come back and your doctor says everything looks normal. You go home with that piece of paper and the word normal stamped on it, and you feel a strange combination of relief and frustration. Relief because nothing is catastrophically wrong. Frustration because you still feel terrible, and the word normal has now foreclosed the conversation about why.
Here is something that does not get explained often enough: normal is a statistical concept, not a clinical one. Laboratory reference ranges are built by testing large populations, finding the middle 95 percent of results, and drawing a line at each end of that range. If you fall inside the line, you are normal. If you fall outside it, you are flagged. What this system does not tell you is whether your result is optimal for your health, or whether it is normal for your age and population group but still meaningfully impacting your function. In menopause, where the gap between normal and optimal can be significant and consequential, this distinction matters enormously.