Health Reference LibraryFerritin 15: what your result means
This entry is part of the Nutri Tailor Health Reference Library — cited research on supplements, nutrients and adjacent areas of health.
Summary
Yes, ferritin 15 µg/L is low. It sits exactly at the WHO deficiency threshold of 15 for healthy adults and well below the 30 µg/L that NICE-aligned UK practice regards as confirmed iron deficiency. Stores this low commonly cause tiredness, poor exercise tolerance, hair shedding and restless legs before anaemia ever shows on a full blood count. The evidence-based response is to find the cause with your GP, correct it with iron alongside vitamin C, and retest ferritin after 8 to 12 weeks.
Free iron and ferritin result interpreter
Enter what you have. Your ferritin alone works; the other fields sharpen the reading. Nothing you enter leaves this device. Nothing is saved. No AI is used, only published UK guideline thresholds.
This tool gives educational interpretation of published evidence. It is not personal dosing advice and it does not diagnose. It knows nothing about your history, symptoms or other results. Interpreting your results over time, alongside everything else about you, is what Nutri365 does.
How it works
Ferritin is the protein your body stores iron in, so serum ferritin reads the size of your iron reserve rather than the iron circulating right now. That is why it falls first: stores drain before haemoglobin drops, which is also why a normal full blood count alongside a ferritin of 15 does not mean all is well. The one caveat that matters is inflammation, because ferritin rises with infection and inflammatory illness regardless of iron; a CRP test alongside makes 15 trustworthy, and a genuinely low result is never explained away by inflammation, only masked upward by it.
Guideline positions
WHO 2020 places iron deficiency in apparently healthy adults at ferritin below 15 µg/L, and a result of 15 sits exactly on that line. UK NICE-aligned practice confirms deficiency below 30 µg/L, a threshold with 92 percent sensitivity and 98 percent specificity, and NHS Scotland guidance notes below 40 is 98 percent on both, so 15 sits 15 below the UK confirmation threshold. A CRP alongside makes the number trustworthy, because inflammation raises ferritin and a raised CRP means true stores may be lower still.
Practical framework
A ferritin of 15 µg/L sits exactly on the WHO deficiency line and 15 under the UK threshold of 30, so it is low by every definition in use.
Three steps, in order. First, the cause: book the GP conversation, because correcting a number without knowing why it fell invites it to fall again. Second, correction: food does the foundations, red meat, legumes, dark leafy greens paired with vitamin C sources, while tea and coffee move away from iron-containing meals; a supplement closes the gap food cannot, and Iron & Vitamin C pairs the mineral with the vitamin that improves its absorption, taken alternate days which NHS guidance supports as effective and better tolerated. Third, proof: haemoglobin responds within about 4 weeks, but stores refill slowly, so retest ferritin at 8 to 12 weeks and expect months, not days. The full repletion arc is mapped in how long iron supplementation takes. For readers who decide on a supplement, Nutri Tailor stocks Iron & Vitamin C in the UK. To check your own result against the UK ranges, the Nutri Tailor free blood test result interpreter reads ferritin and the iron panel, vitamin D, B12 and folate. The Ferritin 15: is that low, and what should you do? entry covers this band of results in full.
Sources
- 2020. WHO guideline on use of ferritin concentrations to assess iron status. World Health Organization.
- 2024. Iron deficiency guidelines. NHS Scotland Right Decisions.
- 2023. Ferritin interpretation, a guide for GPs. Royal United Hospitals NHS (NICE CKS aligned).