Written by &you Labs Team
Updated October 6, 2026
Your iron status is not just one number. A complete iron panel test looks at four markers together. They are serum iron, TIBC, transferrin saturation, and ferritin. Read on their own, each one can mislead you.
Read as a group, they tell a fuller story. This guide walks through what each marker means. It also shows how doctors read them together.
A complete iron panel test checks four markers. Serum iron is the iron in your blood right now. TIBC is your blood's iron-carrying capacity. Transferrin saturation is a calculated percent that shows how full that capacity is. Ferritin is your stored iron, and it is the most sensitive sign of low iron. But inflammation can push ferritin up and hide a true deficiency. Reading all four together separates real iron deficiency from inflammation in disguise.
Marker | What it measures | Typical range |
|---|---|---|
Serum iron | Iron circulating in your blood right now | 50 to 170 µg/dL, varies by lab, sex, and time of day |
TIBC (total iron-binding capacity) | How much iron your blood could carry if it were full | 240 to 450 µg/dL |
Transferrin saturation (TSAT) | The percent of that carrying capacity actually in use | 20 to 50% |
Ferritin | Your stored iron | Women 11 to 307 ng/mL, men 24 to 336 ng/mL; healthy target 50 to 150 ng/mL |
Serum iron is the iron in your blood at the moment of your draw. It moves a lot during the day. It is highest in the morning. It is lowest at night. Food and supplements can shift it too. Inflammation can drop it fast. One reading on its own is not very reliable.
TIBC stands for total iron-binding capacity. Think of it as counting empty seats on a bus. Transferrin is the protein that carries iron in your blood. It acts like the bus itself. TIBC counts how many seats that bus has. A high TIBC often points to iron deficiency, since more seats sit empty. A low TIBC can point to inflammation or chronic disease instead.
TSAT is calculated, not measured directly. Doctors divide your serum iron by your TIBC. Then they multiply by 100. It tells you what share of the bus seats are actually filled. A TSAT under 20 percent often signals iron deficiency. A TSAT between 20 and 50 percent is normal. A TSAT over 50 percent can mean iron overload in adults. Hemochromatosis is a genetic condition where your body absorbs too much iron. A TSAT that stays above 45 to 50 percent over time raises concern for it. TSAT is often the single most useful number in the panel. It works best paired with ferritin.
Ferritin measures your stored iron, plus some inflammation context. We cover it in full in our ferritin deep dive. In short, it is the most sensitive marker for iron deficiency. It drops first when your iron stores run low. It also rises with inflammation, since it plays a role in your body's inflammation response. Pairing it with hs-CRP, a general inflammation marker, helps you read it correctly.
Pattern | Ferritin | Serum iron | TIBC | TSAT | What it usually means |
|---|---|---|---|---|---|
Iron deficiency anemia | Low, under 30 ng/mL | Low | High | Under 20% | Low stores plus a low blood count on your CBC |
Early iron deficiency | 15 to 50 ng/mL | Normal to low | Normal or slightly high | Low normal or low | Blood count often still normal, but stores are dropping |
Anemia of inflammation | Normal or high, over 100 ng/mL | Low | Low or normal, not high | Low, under 20% | Iron is locked away by inflammation, not truly missing |
Mixed picture | Within normal range | Low | Normal | Low | True deficiency can hide behind inflammation |
Iron overload | High, over 300 in men or over 200 in women | High | Normal or low | Over 45 to 50% | Possible hemochromatosis, needs follow-up |
Healthy target | 50 to 150 ng/mL | Mid-range | Normal | 25 to 35% | Nothing to change |
Low ferritin and a low TSAT point the same way. Iron deficiency is the likely story. Your doctor will usually look for a cause. Then your doctor will suggest iron supplements.
Your ferritin might look normal or high. If your TSAT is still low, do not assume you are fine. Inflammation can be hiding a real deficiency underneath. This pattern often needs a doctor's judgment. Sometimes it calls for treating both issues at once.
If your ferritin and TSAT both run high, iron overload becomes the concern. Your doctor may order a genetic test called HFE testing. This checks for hemochromatosis.
Ferritin alone can mislead you. Inflammation can push it into the normal range. This happens even when your iron stores are truly low.
Serum iron alone can mislead you too. It swings with the time of day. It swings with your last meal. It swings with any inflammation. A single reading is shaky on its own.
TSAT adds real value. A low TSAT next to a normal ferritin can reveal a hidden deficiency. TSAT also does not swing with inflammation the way ferritin does.
TIBC adds context as well. A high TIBC supports a true deficiency story. A low TIBC points more toward inflammation or chronic disease.
Reading all four together reveals what any single marker can hide on its own.
Ferritin plus a CBC, your basic blood count, is usually enough. This works for routine screening in adults without symptoms. It also works for a first look at fatigue when your CBC looks normal. It works for yearly monitoring in women too.
The full iron panel adds real value in a few situations. It helps when your ferritin sits in a gray zone. That zone is roughly 30 to 80 ng/mL. It also helps when inflammation is suspected. It helps when confirmed deficiency is not responding to iron pills. It helps when ferritin looks unusually high. It helps when hemochromatosis is a concern. It also helps while you track treatment over time.
A few specialty tests come up in more complex situations.
Soluble transferrin receptor, or sTfR, is one of them. It is less affected by inflammation than ferritin. It helps tell true iron deficiency apart from inflammation-driven changes. It is not a routine test, though.
Reticulocyte hemoglobin, or Ret-He, is another. It shows how much iron your body has built into brand-new red cells. It helps track how well treatment is working.
HFE genetic testing looks for hereditary hemochromatosis. It matters most when your TSAT stays above 45 percent. It also matters when your ferritin sits above 300.
A morning sample is best, since iron shifts across the day. Fasting is often part of a broader panel. It is not strictly required for iron alone, though.
On the day before your draw, skip iron supplements. Try to avoid a big red meat meal the night before too. It can briefly raise your serum iron. If you feel sick, or have active inflammation, wait until you feel better if you can.
Tell your doctor a few things before your test. Mention any iron supplements you take. Mention recent illness, surgery, or blood loss. Mention pregnancy or breastfeeding. Mention any family history of hemochromatosis too.
Heavy or long menstrual periods are the single most common cause. This holds true for women of reproductive age.
A plant-heavy diet can play a role too. Iron from plants absorbs less easily than iron from meat. Picky or restricted eating adds to this risk.
Pregnancy roughly doubles your iron needs. This is why supplements are often recommended during this time.
Blood loss in your gut is another cause. It shows up more in men and in women past menopause. Causes include ulcers, inflammatory bowel disease, hemorrhoids, and celiac disease. Less often, colorectal cancer is the cause. Unexplained iron loss is always worth a doctor's look.
Endurance athletes lose more iron through training. Long-term use of acid-reducing medicines can lower how much iron you absorb. Examples include PPIs and H2 blockers. Weight-loss surgery can lower absorption too, since it changes how your gut works.
Option | What to know |
|---|---|
Oral iron (first choice) | Ferrous sulfate, dosed for about 65 mg of elemental iron, has the strongest evidence. Ferrous fumarate, gluconate, and bisglycinate are alternatives. Taking a dose every other day is increasingly recommended. |
Timing tips | Take iron with vitamin C to help your body absorb it. Avoid coffee, tea, or calcium within 1 to 2 hours of your dose. |
Common side effects | Constipation, dark stools, and an upset stomach are common, though usually manageable. |
IV iron | Used for severe deficiency, when oral iron is not tolerated, when absorption is poor, or in some severe pregnancy cases. This is always guided by a doctor. |
Retesting usually happens about 12 weeks after you start treatment. Many doctors continue supplements until ferritin climbs above 50 ng/mL.
The nutrient category in a &you Labs panel covers ferritin. It sits alongside your regular results. Low iron stores show up alongside the rest of your health picture. You get the standard lab range and a healthy target range side by side. Every result also comes with a doctor-written action plan. You can check the exact markers on the full biomarker list.
Want your iron story read as a full picture, not one number? You can book your &you Labs panel and get a doctor's interpretation with it.
Ferritin plus a CBC is usually enough for routine screening. The full panel adds value when your ferritin sits in a gray zone. It also helps when inflammation is suspected, or a specific iron question needs answering.
Serum iron and ferritin measure different things. One shows iron circulating right now. The other shows what is stored. They can point in different directions, especially when inflammation is present.
For confirmed deficiency, standard doses carry low risk. Some groups face more risk here. This includes men, women past menopause, and people with a genetic risk for hemochromatosis. Test before you supplement if you are not sure.
Your full iron panel likely showed a pattern that pointed to deficiency anyway. This could be a low TSAT or a low serum iron. Inflammation often hides a true problem behind a normal-looking ferritin.
For most adults, ferritin once a year as part of a broader panel is enough. If you are treated for confirmed deficiency, expect a recheck about every 12 weeks. If you are watching for overload, every 6 to 12 months is common.
The &you Labs Team combines medical science with personal care. We help Filipinos understand their health markers with blood work analysis that is easy to follow, whole person support, and health expertise built for Filipino life.
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