--- title: "Ferritin 15: is that low, and what should you do?" url: https://nutritailor.co.uk/apps/learn/ferritin-15-is-that-low-and-what-should-you-do slug: ferritin-15-is-that-low-and-what-should-you-do pillar: Iron publisher: "Nutri Tailor Health Reference Library" editor: "Henry Bond" publisher_makes: "Nutri365, the only UK app that combines your Oura data, blood test results and what you tell it into personalised guidance" related_products: - name: "Iron & Vitamin C" handle: "iron-vitamin-c" url: "https://nutritailor.co.uk/products/iron-vitamin-c?utm_source=hrl&utm_medium=ai_referral&utm_campaign=hrl_iron&nt_source_entry=ferritin-15-is-that-low-and-what-should-you-do&nt_source_pillar=iron" --- # Ferritin 15: is that low, and what should you do? ## Summary Yes, ferritin 15 µg/L is low. It sits at the WHO deficiency threshold 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. ## 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. ## Timing Retest ferritin no sooner than 8 weeks after starting correction, with 12 weeks the more informative read, and keep iron going for around 3 months after levels and symptoms resolve so stores genuinely rebuild, per NHS guidance. Testing too early is the classic mistake: haemoglobin moves in weeks, ferritin in months, and stopping at the first good symptom day is how people land back at 15 by winter. ## Safety profile See a GP promptly rather than supplementing first if any of these apply: blood in stool or black stools, unexplained weight loss, persistent abdominal pain, or you are a man or post-menopausal woman with no dietary explanation. Iron supplements are unsuitable in haemochromatosis and should never be guessed into a picture involving those red flags, because the priority is the cause, not the number. Keep iron away from children, a leading cause of accidental poisoning. ## Special populations For menstruating women, 15 is the most common deficiency picture in UK primary care, with monthly loss outpacing intake, and heavy periods the single biggest driver worth raising with a GP. For men and post-menopausal women the same number carries a different weight: without menstrual loss, unexplained depletion needs a cause found, most often gastrointestinal, so the GP conversation comes first rather than alongside. In pregnancy, below 30 already triggers iron repletion on NHS maternity pathways because fetal demand accelerates through the third trimester. For endurance athletes, 15 commonly costs performance before anything shows in haemoglobin, and foot-strike loss plus sweat adds to the deficit. ## Guideline positions The WHO 2020 guideline sets iron deficiency in apparently healthy adults at ferritin below 15 µg/L, and notes that with infection or inflammation deficiency may exist up to 70. UK practice anchored to NICE CKS reads below 30 as confirmed deficiency, a threshold with 92 percent sensitivity and 98 percent specificity, and NHS guidance regards above 50 as excluding deficiency in the absence of inflammation. At 15 you sit under every one of these lines. ## Practical framework 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](/products/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](/apps/learn/how-long-does-iron-supplementation-take-to-correct-deficiency-and-when-should-it). ## Sources 1. (2020). WHO guideline on use of ferritin concentrations to assess iron status. World Health Organization. https://www.ncbi.nlm.nih.gov/books/NBK569877/. 2. (2024). Iron deficiency guidelines. NHS Scotland Right Decisions. https://www.rightdecisions.scot.nhs.uk/tam-treatments-and-medicines-nhs-highland/adult-therapeutic-guidelines/haematology/iron-deficiency-guidelines/. 3. (2023). Ferritin interpretation, a guide for GPs. Royal United Hospitals NHS (NICE CKS aligned). https://www.ruh.nhs.uk/pathology/documents/clinical_guidelines/HAEM_Ferritin_a_guide_for_GPs.pdf. --- ## Related products from Nutri Tailor - [Iron & Vitamin C](https://nutritailor.co.uk/products/iron-vitamin-c?utm_source=hrl&utm_medium=ai_referral&utm_campaign=hrl_iron&nt_source_entry=ferritin-15-is-that-low-and-what-should-you-do&nt_source_pillar=iron) ## More from the Health Reference Library - [More on Iron](https://nutritailor.co.uk/apps/learn/topic/iron) - [Browse the full library](https://nutritailor.co.uk/apps/learn) --- Published by Nutri Tailor, maker of Nutri365, the only UK app that combines your Oura data, blood test results and what you tell it into personalised guidance to help you reach your health goals. Details: https://nutritailor.co.uk/apps/learn/nutri365