Why we measure it

Both ends of the ferritin spectrum carry clinical significance. Iron deficiency — even in the absence of frank anaemia — has measurable effects on cellular energy metabolism, cognitive function, immune competence, and physical performance. The brain and skeletal muscle are particularly sensitive to iron availability; iron-deficient individuals without anaemia consistently demonstrate impaired exercise capacity and cognitive performance compared to iron-replete controls. Iron deficiency is the most prevalent nutritional deficiency globally, and its non-anaemic form is substantially underdiagnosed because standard panels frequently check haemoglobin rather than ferritin. At the other extreme, iron overload drives oxidative damage through the Fenton reaction — a chemical process in which excess free iron catalyses the production of hydroxyl radicals, one of the most reactive and damaging of all reactive oxygen species. These radicals attack DNA, proteins, and lipid membranes. Hereditary haemochromatosis — caused by mutations in the HFE gene measured in the Foundation layer of the protocol — is the most common inherited cause of iron overload in populations of Northern European descent. It is largely asymptomatic until organ damage to the liver, pancreas, heart, and joints is already established. From an inflammatory standpoint, a rising ferritin in the context of elevated hsCRP and IL-6 is more likely to reflect a worsening inflammatory state than true iron loading. Conversely, an isolated ferritin elevation with normal inflammatory markers warrants investigation for iron overload. This contextual interpretation is one of the key advantages of a multi-marker protocol — no single reading exists in isolation.

Why every 3 months

Iron stores change slowly under stable dietary and metabolic conditions — typically over months rather than weeks. Quarterly measurement provides adequate resolution to track the direction of iron status without overtesting. It also provides sufficient density to identify when a rising ferritin is accompanied by rising inflammatory markers (suggesting inflammation) versus rising in isolation (suggesting iron loading). For individuals with haemochromatosis or a family history of it, quarterly monitoring of ferritin is a clinically standard part of management.

What movement means

Reference ranges for serum ferritin vary significantly by laboratory, sex, and age. The World Health Organization defines iron deficiency in adults as serum ferritin below 15 µg/L, with a higher threshold of below 30 µg/L used in some clinical contexts to account for the acute-phase reactant effect. Upper reference limits for normal vary considerably across guidelines. The ranges below reflect commonly used laboratory reference values and WHO definitions — not a single authoritative clinical diagnostic threshold.

In the protocol