Ferritin 19: what your result means

How it works

Ferritin is the protein that stores iron, and the blood level broadly tracks how much iron the body holds in reserve. Because stores are drawn down before red blood cell production is affected, ferritin falls first, often months before haemoglobin moves, which is why a person can have depleted iron with a blood count still printed as normal. Ferritin is also an acute-phase protein: infection, inflammation and higher body weight push the number up, which can hide genuinely low stores. The number is therefore read alongside symptoms, CRP where available, and the rest of the iron panel rather than in isolation.

Guideline positions

NICE guidance classes adult ferritin below 30 ug/L as iron deficiency, while the WHO threshold of 15 ug/L marks severely depleted stores, and many UK laboratory reference ranges still flag results only below the lower cut-off. This gap between the reference range and the guideline threshold is why results in the teens and twenties are often reported as normal yet meet the NICE definition of deficiency. UK practice for confirmed deficiency centres on identifying the cause with a GP, dietary iron, and supplementation where appropriate, with a repeat test typically 8 to 12 weeks after any change.

Practical framework

Your ferritin of 19 ug/L clears the WHO severe-depletion threshold of 15 by 4 but sits 11 under the NICE deficiency cut-off of 30, the level UK guidance classes as iron deficiency even when the report prints the result as normal. Clearing 30 on a retest is the target.

A result in this band suggests raising it with your GP, particularly if you have symptoms, since guidance looks for the cause behind low iron alongside correcting the level. Where iron is appropriate, the evidence favours consistent daily intake with a vitamin C source and away from tea and coffee, with a retest around three months on to see whether stores are refilling. A raised CRP makes the ferritin unreliable, and a transferrin saturation below 20 percent strengthens the iron deficiency reading further.

You can read your own numbers against these thresholds with the free blood test result interpreter on this site. It runs entirely on your device, nothing is saved, and pasting your report fills the values in for you.