Your values are all normal

Normal means: not sick enough

“Your values are all normal” is the sentence that frustrates people most, because it is true and still does not help. In lab medicine, normal means: you sit inside the reference range. And that range is built from 95% of the population. The problem: if half the population has a suboptimal vitamin D level, then “suboptimal” is statistically normal.

A ferritin of 18 ng/ml is lab-normal at the GP. The reference range often starts at 15 ng/ml. In a functional reading of iron stores, that is already advanced depletion - even when haemoglobin is still fine. A WHO-supported systematic review shows: when bone marrow is completely empty of iron, mean ferritin sits at 15.1 µg/L (Garcia-Casal et al., 2018 [1]). In other words, the lower end of the standard range sits almost on the level of an empty store. We look at that gap in more detail in ferritin in women.

That is not your GP’s fault. They work with the system they have. The system is built to diagnose disease, not to map potential. And that is the gap.

What your GP does not test

A large blood count sounds comprehensive. In reality it mainly counts your blood cells: red and white cells, platelets, haemoglobin. Those values matter. They say nothing about your iron store, your thyroid function, your vitamin D level or your long-term blood sugar.

The markers that show up most often with exhaustion, brain fog and a vague sense of being “off” are simply not part of a standard blood count:

• Ferritin (iron store): rarely requested, even though iron deficiency without anaemia is the most common nutrient deficit worldwide
• Vitamin D (25-OH): not a statutory benefit without a specific suspicion, even though more than 60% of adults in Germany are undersupplied (Rabenberg et al., 2015 [6])
• Thyroid (TSH, free T3, free T4): often only TSH is measured, not the active hormones - why that misses most patterns is in TSH alone is not enough
• HbA1c (long-term blood sugar): can flag insulin resistance earlier than fasting glucose, but is usually measured only when diabetes is already suspected
• Vitamin B12: especially relevant on a vegetarian or vegan diet, and not part of the routine check

Five supplements in the cupboard, and no idea whether any of them is doing anything. That is not targeted. That is a watering can. And that is what happens when the data are missing.

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What I keep seeing in patients

Honestly: the pattern is almost always the same. The woman is 32 to 48, works a lot, looks after everyone except herself, and says: “I am just tired. But not the kind of tired that sleep fixes.” She has been to the GP. Blood count normal. Thyroid? TSH just under 4. Normal. Ferritin? Never measured.

Then we look properly. Ferritin at 22. Vitamin D at 28 ng/ml. TSH at 3.8 with free T3 at the lower edge. Each value on its own: still lab-normal. Together they form a pattern that can help explain her exhaustion - education about combined markers, not a diagnosis from a lab printout.

A meta-analysis of six randomised trials shows: already at ferritin below 50 µg/L, iron supplementation improved fatigue significantly, with an effect size of 0.33 (Yokoi & Konomi, 2017 [2]). All of those women had normal haemoglobin. What was not normal: their ferritin. A landmark RCT in non-anaemic women with unexplained fatigue found the same direction of effect (Verdon et al., 2003 [5]), and a later systematic review came to a similar conclusion for iron repletion without anaemia (Houston et al., 2018 [4]). Vaucher et al. (2012) [3] showed the benefit most clearly when ferritin was below 50 µg/L - not when stores were already full.

That is why I tell my patients: do not supplement on suspicion. Measure first, then act. Measure, do, measure.

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