What the labs mean
Iron labs decoded, in plain English.
A single number rarely tells the story. Ferritin, serum iron, TIBC, transferrin saturation, and CBC work together to answer: do I have iron in storage, is it moving, is it being delivered, and am I anemic yet?
Every iron test, one line each
| Test | What it is | Low may mean | High may mean |
|---|---|---|---|
| Ferritin | Your iron storage tank | Low iron stores | Inflammation, infection, liver issues, or iron overload |
| Serum iron | Iron in your blood today | Low circulating iron | Recent iron intake, iron overload, liver issues |
| TIBC | How many empty iron taxis are out looking | Can be low with inflammation / chronic illness | Often high when the body is iron-starved |
| Transferrin | The protein that carries iron | Inflammation or liver issues | Often high when iron is low |
| Transferrin saturation (TSAT) | Percent of iron taxis that are full | Low iron delivery | Iron overload |
| CBC | Checks red blood cells and anemia | Anemia or blood cell problem | Depends on which part is high |
| Hemoglobin | Oxygen-carrying protein in red cells | Anemia | Dehydration, lung/heart issues |
| MCV | Size of red blood cells | Small cells → often iron deficiency | Large cells → often B12 / folate deficiency |
| RDW | How uneven red cell sizes are | — | Often rises with developing iron deficiency |
| Reticulocyte count | Baby red blood cells | Marrow may not be making enough new cells | Body is responding to blood loss or treatment |
| B12 & folate | Other nutrients needed for blood | Another cause of anemia or fatigue | Usually less clinically important |
| MMA (methylmalonic acid) | Deeper B12 marker | — | Suggests B12 deficiency |
Ferritin ranges
The pantry check
Under 15
Very low stores — treat
Under 30
Low stores — treat if any symptoms
30–50
Often iron deficient with symptoms
50–100
Symptom-supportive range for many
Over 100
Usually adequate — check inflammation & liver
Ferritin can look falsely normal or high with inflammation, infection, or liver disease. Always interpret alongside transferrin saturation.
Pattern recognition
What the combinations mean
- PatternLow ferritin + low iron + high TIBC + low saturationClassic iron deficiency
- PatternNormal or high ferritin + low saturationPossible inflammation blocking iron use ('anemia of inflammation')
- PatternHigh iron + high saturationPossible iron overload — evaluate hemochromatosis
- PatternLow hemoglobin + low MCV + low ferritinIron-deficiency anemia
- PatternLow hemoglobin + high MCVThink B12, folate, thyroid, liver, alcohol, medication, or marrow issue
Now what?
If your ferritin is low or your symptoms match, the plan is food first, supplements if needed, and address whatever caused the loss.