Have you been told your bloodwork is “normal” but you still feel exhausted, foggy, anxious, or just… off? You’re not imagining it. The reference ranges your GP uses to interpret blood tests were never designed to tell you whether you’re healthy. They were designed to tell you whether you’re sick. There’s a meaningful gap between those two things — and that gap is where a lot of patients quietly suffer.

This is one of the first conversations I have with most new patients at Precision Healthcare Solutions. Because once you understand how reference ranges actually work, the picture changes.

How reference ranges actually work

A “normal” range on a lab report is a statistical artefact. The lab takes results from a large pool of people who happened to be tested over a given period, removes the outliers at the top and bottom, and reports the middle 95% as “normal”. That’s it. It is not a range of optimal values, it is a range of commonly observed values in a population that includes a great many people who are tired, inflamed, deficient, or in early stages of disease they don’t know about yet.

So when your result lands inside that range, all your GP can confidently say is: “you’re not unusually far from the average”. That is a much weaker claim than “you’re well”.

Three markers we read very differently

Below are three of the most common examples I encounter where a “normal” result deserves a much closer look.

Vitamin D (25-hydroxyvitamin D)

Most South African labs flag a deficiency only below roughly 30 ng/mL. Functional medicine literature consistently points to 50-80 ng/mL as the range associated with optimal immune function, mood regulation, bone health, and reduced systemic inflammation. A result of 32 ng/mL is technically “normal” — and clinically suboptimal for many of my patients. Repleting vitamin D into the optimal range frequently changes how someone feels within weeks.

Ferritin

Ferritin is a measure of iron storage, and the conventional lower limit (often around 15 ng/mL for women) catches only the most depleted patients. Hair shedding, fatigue, restless legs, and reduced exercise tolerance commonly emerge well before someone is technically iron-deficient. A ferritin of 22 ng/mL is “normal” — and in a fatigued woman with hair loss, almost always part of the problem.

TSH and the rest of the thyroid panel

A TSH of 4.0 mIU/L is inside most labs’ reference range. It is also higher than the level at which most thyroidologists would describe optimal pituitary-thyroid signalling. More importantly, TSH on its own tells you very little — you also want free T3, free T4, reverse T3, and thyroid antibodies (TPO and Tg) to understand whether your thyroid is genuinely well, sluggish, autoimmune, or being suppressed by inflammation or stress. A “normal” TSH with low free T3 and high reverse T3 is a real clinical pattern. It does not show up if you only run TSH.

What “optimal” actually means — and why it’s individual

“Optimal” is not a single number. It is a range that takes into account your symptoms, your goals, your age, your sex, your medical history, and what your body has been through. A vitamin D level that’s fine for an asymptomatic 25-year-old may be inadequate for a 55-year-old recovering from cancer treatment. A ferritin of 60 may be plenty for a sedentary man and insufficient for a competitive runner.

This is why functional medicine relies on context, not just numbers. Two patients with identical bloodwork can — and frequently do — need completely different protocols.

How we approach bloodwork at Precision Healthcare Solutions

When you come in for a comprehensive consultation, I read your bloodwork against optimal ranges, not just statistical normals. Where the standard panel is incomplete, I order what’s missing — comprehensive thyroid markers, methylation-related vitamins (B12, folate, homocysteine), inflammation markers (hs-CRP, ferritin, fibrinogen), and metabolic-health markers (fasting insulin, HbA1c, lipid sub-fractions). Where indicated, we go further: SNP genetic analysis, organic acid testing, micronutrient panels, heavy metal testing, and stool microbiome analysis.

The aim is not to find something wrong. The aim is to build a complete biological picture so that the protocol we design — nutrition, supplementation, lifestyle, targeted therapies — is genuinely personalised, not generic.

If you’ve been told your bloodwork is “normal” but you don’t feel well, that result is the start of the conversation, not the end of it. Book a comprehensive consultation and let’s look at the whole picture.

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Educational content only. This article is not medical advice and should not replace consultation with a qualified healthcare provider. Always discuss your individual situation with your doctor before changing any treatment.