“You’re Fine.” But You Don’t Feel Fine.

Author: Rohan Smith | Functional Medicine Practitioner | Adelaide, SA

Blood test results medicine can sometimes be misleading. While your lab results may come back “normal,” you could still be experiencing fatigue, unexplained symptoms, or chronic health issues. Conventional blood tests focus on disease detection and general markers, but they often miss subtle imbalances that could be affecting your body. Functional medicine digs deeper, analyzing factors like nutrient deficiencies, hormonal fluctuations, and metabolic stress to help uncover hidden issues that standard tests overlook. In this article, we explore why blood test results may not tell the whole story and how functional medicine offers a more comprehensive approach to your health.

You wake up already tired. Midday hits and you’re dragging. Maybe your hair’s thinning or your digestion’s off. You finally go see your GP, run the usual tests, and wait for answers.

The call comes: “Everything looks fine.”

But it doesn’t feel fine.

This is one of the most common frustrations I hear from people walking into my Adelaide clinic. On paper, their health looks “normal,” but day-to-day life says otherwise.

If you’ve ever been told your labs are fine when your body says otherwise, keep reading. You’re not imagining things. You may simply need a different way of interpreting blood tests.

Quick Answer

Standard blood test reference ranges are designed to detect overt disease, not early dysfunction or suboptimal physiology. As a result, symptoms such as fatigue, brain fog, mood changes, or poor sleep can persist even when results fall within laboratory “normal” ranges. A functional interpretation of bloodwork considers patterns, context, and ranges associated with optimal function rather than disease detection alone (1–3).

Why “Normal” Isn’t Always Healthy

Conventional blood tests themselves are not the problem. The limitation lies in how results are interpreted.

Reference ranges used in general practice are statistically derived from population averages and are intended to identify disease states. Values that fall within these ranges are typically considered acceptable, even when symptoms are present (1).

• “Normal” ranges reflect population averages, not optimal health
• These populations often include individuals with chronic conditions
• Biochemical values can fall within range while still being associated with symptoms (2)

Functional vs. Conventional Interpretation

Functional medicine uses the same laboratory tests as conventional medicine but applies a different clinical lens.

Rather than asking whether a diagnosable disease is present, the focus is on whether physiological systems are functioning optimally and whether early patterns of stress or depletion are emerging (3,4).

Examples of interpretation differences:

• Thyroid-stimulating hormone (TSH): A value between 0.4–4.0 mIU/L is commonly reported as normal. Research suggests that values above ~2.0 mIU/L may be associated with hypothyroid symptoms in some individuals, even when overt disease is not diagnosed (5,6).
• Vitamin B12: Levels above 150 pmol/L may meet laboratory cut-offs, yet neurological and cognitive symptoms have been observed at higher concentrations, suggesting functional insufficiency in some patients (7,8).

Case Example: Persistent Fatigue With “Normal” Results

Patient name changed for privacy.

A 37-year-old woman presented with persistent fatigue, brain fog, and reduced work capacity lasting over 12 months. Previous blood tests were reported as “within normal limits.”

Review of these results identified several values that, while technically normal, were potentially relevant in the context of her symptoms:

• Ferritin of 18 ng/mL — within reference range, but below levels commonly associated with optimal energy and iron sufficiency (9,10)
• TSH of 3.7 mIU/L — within laboratory range, but consistent with early thyroid stress in symptomatic individuals (5)
• Vitamin B12 of 260 pmol/L — adequate by reference standards, yet potentially suboptimal for neurological function (7)
• Vitamin D of 55 nmol/L — at the low end of sufficiency for immune and mood-related outcomes (11,12)

With targeted nutritional and lifestyle support, the patient reported gradual improvements in energy, cognitive clarity, and mood over several months. This case is illustrative and does not imply guaranteed outcomes.

What Could Your “Normal” Bloodwork Be Missing?

If you are experiencing symptoms such as:

• Persistent low energy or chronic fatigue
• Brain fog or memory difficulties
• Poor sleep or mood fluctuations
• Cold sensitivity, hair thinning, or dry skin
• Intermittent digestive symptoms

…it may be that subtle biochemical patterns are being overlooked rather than absent (2,3).

Next Steps

Interpreting bloodwork alongside symptoms, medical history, and trends over time often provides more clinically meaningful insight than isolated reference values alone.

Curious About What Your Results Really Say?

If you have been told your blood tests are normal but you still feel unwell, a more detailed review may be helpful.

You can book a free 15-minute discovery call via Elemental Health and Nutrition to discuss your health history, review existing bloodwork, and determine whether this approach is appropriate for you.

References

1. Jones G, Barker A. Reference intervals. Clin Biochem Rev. 2008.
2. Fraser CG. Biological variation: from principles to practice. AACC Press. 2001.
3. Greenhalgh T, et al. Evidence based medicine: a movement in crisis? BMJ. 2014.
4. Kohlstadt I. Integrative medicine: principles for practice. McGraw-Hill. 2012.
5. Surks MI, Hollowell JG. Age-specific distribution of serum TSH. J Clin Endocrinol Metab. 2007.
6. Hoermann R, et al. Homeostatic control of the thyroid–pituitary axis. Front Endocrinol. 2015.
7. Lindenbaum J, et al. Neuropsychiatric disorders caused by cobalamin deficiency. N Engl J Med. 1988.
8. O’Leary F, Samman S. Vitamin B12 in health and disease. Nutrients. 2010.
9. Cook JD. Diagnosis and management of iron-deficiency anaemia. Best Pract Res Clin Haematol. 2005.
10. Favrat B, et al. Iron deficiency without anemia. Blood. 2014.
11. Holick MF. Vitamin D deficiency. N Engl J Med. 2007.
12. Souberbielle JC, et al. Vitamin D and musculoskeletal health. Lancet Diabetes Endocrinol. 2014.
13. Allen LH. Causes of vitamin B12 and folate deficiency. Food Nutr Bull. 2008.
14. McClung JP, et al. Iron status and fatigue. Am J Clin Nutr. 2014.
15. Monk JM, et al. Micronutrients and fatigue. Nutrients. 2016.