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Hormonal
Ferritin is the protein your body uses to store iron, and measuring it in blood gives an indirect but reliable picture of how much iron you actually have in reserve — not just how much is circulating right now, which is what a simple iron test would show. That distinction matters, because iron stores can run low well before the classic signs of anaemia appear, making ferritin one of the earliest and most sensitive ways to catch iron deficiency before it progresses. It's usually ordered alongside a CBC when that test's red cell findings already suggest anaemia, to help pin down whether low iron is actually the cause.
The test reports your blood ferritin level, typically in nanograms per millilitre. Normal ranges differ by sex, generally around 30 to 400 ng/mL for men and 13 to 150 ng/mL for women, a difference that mostly reflects women's regular iron losses through menstruation. A low ferritin level usually signals depleted iron stores, often appearing before haemoglobin itself drops low enough to be called anaemia. A high ferritin level, less commonly, can point toward iron overload or can simply reflect inflammation elsewhere in the body, since ferritin also rises as part of a general inflammatory response.
Because ferritin often falls before haemoglobin does, it's considered a more sensitive early marker for iron deficiency than a CBC alone — someone can have normal haemoglobin today and still have a ferritin level low enough to predict anaemia developing soon. That's part of why it's frequently ordered together with, rather than instead of, a CBC: the two tests answer different but related questions.
On the other end of the range, an unexpectedly high ferritin doesn't automatically mean iron overload — several unrelated conditions can raise it too, including liver disease linked to alcohol use, autoimmune disorders such as rheumatoid arthritis, frequent blood transfusions, an overactive thyroid, and true iron overload (haemochromatosis) itself. Because the list is that broad, a high reading on its own is a prompt for more specific follow-up, not a diagnosis of any one of these conditions by itself — your doctor will usually weigh it alongside your symptoms, your other blood results, and sometimes further testing before deciding what, if anything, it points to. This is a good example of why a single number rarely tells the whole story on its own, in either direction, low or high.
Most labs ask you to fast for around 12 hours before this test and schedule it in the morning, since both food and the time of day can shift the result. The test itself is a routine blood draw from a vein, and it's often repeated alongside a CBC a few months into iron supplementation to check that stores are actually rebuilding, not just that symptoms have improved.
Most labs recommend around 12 hours of fasting and prefer the test done in the morning, since both food and time of day can affect the result.
Haemoglobin reflects your current red blood cell status, while ferritin reflects your body's stored iron reserves — and stores can run low well before haemoglobin itself drops, making ferritin an earlier warning sign.
The difference mostly reflects women's regular iron losses through menstruation, which lower typical baseline iron stores compared to men.
No — ferritin also rises as part of the body's general response to inflammation or infection, independent of actual iron levels, so a high result needs to be interpreted alongside the rest of the clinical picture.
The two tests answer related but different questions — a CBC shows the current state of your red blood cells, while ferritin shows your underlying iron reserves, and together they give a fuller picture of anaemia and its cause.
Yes, since iron from plant sources is absorbed less efficiently than iron from meat, people eating a mostly plant-based diet are more likely to have lower iron stores over time.
Fatigue, unusual paleness, and shortness of breath on exertion are common symptoms of low iron stores that often prompt a ferritin test, particularly alongside other CBC findings.
That's set by your doctor based on your specific situation, but it's typically monitored periodically during iron supplementation to confirm stores are actually rebuilding.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
