Introduction to Iron Metabolism and Laboratory Indicators: Iron, Transferrin, TIBC, and Ferritin
Introduction
Iron is one of the essential elements in the human body and plays a critical role in hemoglobin synthesis, oxygen transport, cellular energy production, and numerous enzymatic reactions. An adult human body contains approximately 3–4 grams of iron, most of which is found in the hemoglobin of red blood cells, muscle myoglobin, and cellular enzymes. Only a small fraction of iron circulates in the bloodstream, where it is transported by a protein called Transferrin.
The human body does not have an active mechanism for iron excretion; therefore, iron balance is primarily regulated through its absorption in the small intestine. A hormone called Hepcidin, which is produced in the liver, is the main regulator of iron metabolism. Increased hepcidin levels reduce iron absorption and decrease the release of iron from body stores, whereas reduced hepcidin levels enhance iron absorption and mobilization from storage sites.
Assessment of the body’s iron status cannot be achieved by measuring Serum Iron alone. For an accurate interpretation of iron metabolism, the results of Serum Iron, Transferrin, Total Iron Binding Capacity (TIBC), Ferritin, and in many cases Transferrin Saturation (TSAT) are evaluated simultaneously.

1) Serum Iron
Definition
Serum Iron represents the amount of iron bound to the Transferrin protein in the bloodstream. This test reflects the amount of iron currently being transported in circulation and does not represent the actual iron stores of the body.
Since serum iron concentration is influenced by factors such as dietary intake, time of blood collection, inflammation, and various physiological conditions, it should always be interpreted together with other iron metabolism indicators.
Clinical Applications
Measurement of Serum Iron is used in the following conditions:
• Evaluation of iron deficiency
• Assessment of different types of anemia
• Detection of Iron Overload
• Evaluation of Hemochromatosis
• Monitoring the response to iron supplementation therapy
• Investigation of disorders related to iron metabolism

Causes of Decreased Serum Iron
A decrease in Serum Iron may be observed in the following conditions:
• Iron deficiency
• Chronic blood loss
• Pregnancy
• Malnutrition
• Malabsorption (such as celiac disease)
• Chronic inflammatory diseases
• Acute and chronic infections
• Renal failure
• Certain malignancies

Causes of Increased Serum Iron
An increase in Serum Iron may be observed in the following conditions:
• Primary hemochromatosis
• Repeated blood transfusions
• Excessive intake of iron supplements
• Hemolysis
• Hepatitis and liver diseases
• Sideroblastic anemia
• Beta-thalassemia major

Important Points in the Interpretation of Serum Iron
• Serum Iron exhibits diurnal variation and is usually highest during the early morning hours.
• Fasting blood sampling may improve the accuracy of test results.
• Taking iron supplements before blood collection may cause falsely elevated results.
• Hemolysis of the sample can lead to a falsely increased Serum Iron level.
• Due to daily fluctuations, interpretation of Serum Iron alone is not recommended; it should be evaluated together with Ferritin, TIBC, and Transferrin.

Transferrin
Definition
Transferrin is a glycoprotein that is primarily synthesized in the liver, and its main function is to transport iron in the bloodstream. Each transferrin molecule can bind two ferric iron ions (Fe³⁺) and transport them to tissues such as the bone marrow, liver, and other organs.
Under normal conditions, approximately 20–45% of transferrin binding sites are occupied by iron, while the remaining capacity is available for binding additional iron.

Clinical Importance
Measurement of Transferrin helps physicians evaluate the status of iron transport in the body. This parameter is particularly important in the differential diagnosis of various types of anemia, as well as in the evaluation of liver diseases, malnutrition, and disorders of iron metabolism.

Conditions Associated with Increased Transferrin
Transferrin levels are usually increased in the following conditions:
• Iron deficiency
• Pregnancy
• Estrogen therapy or use of oral contraceptive pills
• Chronic blood loss
• Early stages of iron deficiency
In these conditions, the body increases transferrin production to enhance iron binding, absorption, and transport.

Conditions Associated with Decreased Transferrin
A decrease in Transferrin may be observed in the following conditions:
• Chronic inflammatory diseases
• Severe liver diseases
• Malnutrition
• Nephrotic syndrome
• Hemochromatosis
• Malignancies (cancers)

Total Iron Binding Capacity (TIBC)
Definition
TIBC (Total Iron Binding Capacity) represents the maximum capacity of the Transferrin protein to bind iron.
Since almost all iron-binding capacity in serum is related to Transferrin, the TIBC value indirectly reflects the amount of transferrin present in the blood.
Therefore:
• Increased TIBC usually indicates increased Transferrin levels.
• Decreased TIBC usually indicates decreased Transferrin levels.

Clinical Applications
Measurement of TIBC, along with Iron and Ferritin, provides valuable information about the body’s iron storage status and is used in the diagnosis and evaluation of the following conditions:
• Iron deficiency
• Iron overload
• Chronic diseases
• Liver diseases
• Malnutrition

Conditions Associated with Increased TIBC
TIBC levels may increase in the following conditions:
• Iron deficiency
• Pregnancy
• Estrogen therapy
• Chronic blood loss

Conditions Associated with Decreased TIBC
TIBC levels may decrease in the following conditions:
• Chronic inflammatory diseases
• Hemochromatosis
• Liver diseases
• Severe malnutrition
• Nephrotic syndrome

Unsaturated Iron Binding Capacity (UIBC)
Definition
UIBC (Unsaturated Iron Binding Capacity) represents the portion of Transferrin iron-binding capacity that is not yet occupied by iron.
In other words, UIBC indicates the available or unoccupied binding capacity of Transferrin for additional iron binding.
The relationship between these parameters is as follows:
TIBC = Serum Iron + UIBC

Interpretation
In Iron Deficiency:
• Iron ↓
• UIBC ↑
• TIBC ↑
In Iron Overload:
• Iron ↑
• UIBC ↓
• TIBC ↓ or Normal

Ferritin
Definition
Ferritin is the most important iron-storage protein in the body and is mainly found in the liver, spleen, bone marrow, and muscles.
Serum ferritin concentration is considered the best indicator for evaluating the body’s iron stores.
Clinical Importance
Measurement of Ferritin is one of the most sensitive tests for detecting iron deficiency. A decrease in ferritin levels can usually be detected before a reduction in hemoglobin occurs.
Important Note
Unlike Serum Iron, Ferritin is an Acute Phase Reactant.
Therefore, ferritin levels may increase in response to inflammation, infection, and chronic diseases, even when the body’s iron stores are low. For this reason, ferritin should always be interpreted together with other iron parameters such as Serum Iron, TIBC, Transferrin, and Transferrin Saturation (TSAT).

Therefore, Ferritin may increase in the following conditions without the presence of iron overload:
• Infection
• Inflammation
• Autoimmune diseases
• Cancers (malignancies)
• Liver diseases
• Kidney failure
For this reason, a normal or elevated Ferritin level does not always indicate adequate iron stores.

Conditions Associated with Decreased Ferritin
Ferritin levels may decrease in the following conditions:
• Iron deficiency
• Malnutrition
• Chronic blood loss
• Pregnancy

Conditions Associated with Increased Ferritin
Ferritin levels may increase in the following conditions:
• Inflammation
• Infection
• Liver diseases
• Hemochromatosis
• Repeated blood transfusions
• Beta-thalassemia major
• Certain malignancies

Transferrin Saturation (TSAT)
Definition
Transferrin Saturation (TSAT) represents the percentage of Transferrin iron-binding capacity that is occupied by iron.
It indicates how much of the available transferrin binding sites are currently filled with iron.
Calculation Formula:
TSAT (%) = (Serum Iron ÷ TIBC) × 100

Reference Range
The normal range of TSAT in adults is generally 20–45%.

Interpretation
TSAT Less Than 20%
Suggestive of:
• Iron deficiency
• Iron deficiency anemia
• Some chronic diseases

TSAT Greater Than 45%
Suggestive of:
• Hemochromatosis
• Iron overload
• Excessive iron intake
• Repeated blood transfusions

Important Sample Collection Considerations
• The sample should preferably be collected in the morning and in a fasting state.
• Taking iron supplements within 24 hours before blood collection (according to the physician’s recommendation) may affect test results.
• Hemolysis of the sample can cause a falsely elevated Iron level.
• Recent blood transfusions may increase Iron and Ferritin levels.
• Test results should always be interpreted together with the patient’s clinical history, CBC results, and other iron metabolism indicators.

Overall Interpretation of Iron Profile Parameters
Disease / Condition Serum Iron TIBC Ferritin Transferrin Saturation (TSAT) Hemoglobin (Hb) Iron Deficiency Anemia ↓ Low ↑ High ↓ Low ↓ Low (usually <15%) ↓ Low Anemia of Chronic Disease ↓ Low ↓ Low or Normal Normal or ↑ High ↓ Low or Normal ↓ Low Hemochromatosis ↑ High ↓ Low ↑↑ Very High ↑ High
(usually >45%) Normal or ↑ High Thalassemia Minor Normal Normal Normal Normal
(approximately 20-50%) Slightly decreased or below normal Thalassemia Major
(with regular blood transfusions) ↑↑ Very High Low or Normal ↑↑ Very High (often >1000) ↑ High
(usually >80%) Without transfusion: severely decreased Sideroblastic Anemia ↑ High Normal Normal or ↑ High ↑ High ↓ Low
Effects of Medications on Iron Metabolism Indicators
Many medications and supplements can alter Serum Iron, TIBC, and Ferritin levels. These changes may sometimes provide important diagnostic clues, while in other cases they should be considered when interpreting laboratory results.

SGLT2 Inhibitors
(such as Canagliflozin and Empagliflozin)
• May decrease Ferritin by approximately 11.5%
• May increase TIBC by approximately 2.1%

HIF-Prolyl Hydroxylase Inhibitors (HIF-PH inhibitors)
(such as Roxadustat)
By increasing red blood cell production and enhancing iron utilization:
• Increase iron consumption
• May lead to a decrease in Ferritin
• May decrease TIBC

Pentoxifylline (PTX)
By reducing Hepcidin (the hormone responsible for regulating iron metabolism):
• Improves iron availability
• Enhances iron utilization

Antioxidant Supplements
(such as Silymarin, Green Tea, and Grape Seed Extract)
Have been associated with:
• Decreased Ferritin
• Increased TIBC

Anti-inflammatory Drug: Tocilizumab
By reducing inflammatory activity:
• Reduces the effects of inflammation on iron metabolism
• May increase TIBC

Iron Supplements (Oral and Intravenous)
• Directly increase Ferritin levels
• Increase available iron stores

Lactoferrin Supplements
May cause significant increases in:
• Ferritin
• Serum Iron
• Transferrin Saturation (TSAT)

Note: The interpretation of iron profile results should always be performed considering the patient’s clinical condition, inflammatory status, kidney and liver function, CBC parameters, and medication history.

Treatment of Iron Deficiency and Evaluation of Laboratory Changes After Therapy
1. Medications Used in Iron Deficiency
Treatment of iron deficiency is generally aimed at replenishing body iron stores, increasing hemoglobin production, and correcting anemia.

A) Oral Iron Supplements
Oral iron therapy is considered the first-line treatment in most patients.

1. Ferrous Sulfate
Ferrous Sulfate is one of the most commonly used iron preparations.
Mechanism of Action:
• Provides ferrous iron ions (Fe²⁺)
• Increases intestinal iron absorption
• Enhances hemoglobin synthesis
Laboratory Effects After Treatment:
Parameter Change After Treatment Hemoglobin (Hb) ↑ Increased Hematocrit (Hct) ↑ Increased MCV ↑ Increased (correction of microcytosis) MCH ↑ Increased RDW May initially ↑ then decrease Serum Iron ↑ Increased Ferritin ↑ Increased TIBC ↓ Gradual decrease Transferrin ↓ Gradual decrease TSAT ↑ Increased 2. Ferrous Fumarate
Ferrous Fumarate contains a higher percentage of elemental iron compared with some other oral iron preparations.
Applications:
• Iron deficiency anemia
• Pregnancy
• Chronic blood loss
3. Ferrous Gluconate
Ferrous Gluconate generally has better gastrointestinal tolerance.
Suitable For:
• Patients who experience nausea, abdominal pain, or constipation with Ferrous Sulfate

B) Intravenous Iron
Intravenous iron therapy is used when:
• Oral iron absorption is inadequate
• The patient cannot tolerate oral iron
• Rapid correction of iron deficiency is required

1. Iron Sucrose
Applications:
• Chronic kidney disease
• Dialysis patients
• Severe iron deficiency

2. Ferric Carboxymaltose
Advantage:
• Allows administration of a higher iron dose in a single session

3. Iron Dextran
Used in:
• Severe iron deficiency
• Conditions requiring replacement of a large amount of iron

Note: After initiation of iron therapy, laboratory changes occur gradually. Typically, reticulocyte count increases first, followed by improvement in hemoglobin, while restoration of ferritin (iron stores) usually requires a longer treatment period. The response to treatment should be monitored using CBC, Ferritin, Serum Iron, TIBC, and TSAT together.
Effects of Iron Therapy on CBC Parameters
1. Hemoglobin (Hb)
Hemoglobin is the most important indicator of therapeutic response.
After successful initiation of iron therapy:
• An increase of approximately 1–2 g/dL in Hb within 2–4 weeks is expected.
2. Hematocrit (Hct)
Hematocrit increases as the number of red blood cells increases.

3. Mean Corpuscular Volume (MCV)
In iron deficiency anemia, MCV is usually decreased:
Iron deficiency → ↓ MCV
After treatment:
→ MCV gradually increases toward the normal range
However, because the lifespan of red blood cells is approximately 120 days, complete correction of MCV may take several months.

4. Mean Corpuscular Hemoglobin (MCH) and Mean Corpuscular Hemoglobin Concentration (MCHC)
In iron deficiency:
• MCH ↓
• MCHC ↓
After treatment:
• Increased hemoglobin content inside red blood cells
• Improvement of red blood cell pallor (Hypochromia correction)

5. Red Cell Distribution Width (RDW)
In iron deficiency, RDW is usually increased:
Iron deficiency → ↑ RDW
During the early stages of treatment, RDW may temporarily increase because:
• Older red blood cells remain small in size
• Newly produced red blood cells are more normal in size
Over time, RDW gradually returns toward the normal range as the red blood cell population becomes more uniform.

Effects of Iron Therapy on Iron Panel Parameters
Serum Iron
Before Treatment:
↓ Decreased
After Treatment:
↑ Increased
However, due to daily fluctuations and biological variability, Serum Iron alone is not a reliable indicator for monitoring treatment response.
Evaluation should be performed together with:
• Ferritin
• TIBC
• Transferrin
• TSAT

Ferritin
Ferritin is the most important indicator of the restoration of body iron stores.
Before Treatment:
↓ Low
After Treatment:
↑ Gradual increase
Treatment should usually be continued even after correction of Hemoglobin (Hb) levels to allow complete replenishment of iron stores.

TIBC (Total Iron Binding Capacity)
In iron deficiency:
↑ Increased
After treatment:
↓ Decreases toward the normal range
This occurs because the body no longer needs to produce excessive amounts of Transferrin.

Transferrin
Before Treatment:
↑ Increased
After Treatment:
↓ Decreased

UIBC (Unsaturated Iron Binding Capacity)
Before Treatment:
↑ Increased
After Treatment:
↓ Decreased
TSAT (Transferrin Saturation)
Before Treatment:
↓ Below the normal range
After Treatment:
↑ Increased

Medications That May Cause Decreased Iron Levels
Some medications can reduce iron absorption:
Medication Mechanism Proton Pump Inhibitors
(Omeprazole, Pantoprazole) Reduce gastric acid production and decrease iron absorption Antacids Decrease iron absorption Calcium Supplements Compete with iron absorption Some Antibiotics (Tetracyclines, Quinolones) Bind to iron and reduce absorption Cholestyramine Decreases iron absorption
Medications and Conditions That Increase Iron Requirements or Risk of Deficiency
Medication / Condition Effect Erythropoietin Increases iron utilization for red blood cell production Anticoagulants (Warfarin, Heparin) Increase the risk of bleeding NSAIDs (such as Ibuprofen) May cause gastrointestinal bleeding
Summary of Laboratory Changes After Successful Iron Therapy
Parameter Before Treatment
(Iron Deficiency) After Successful Treatment Hb ↓ Decreased ↑ Increased Hct ↓ Decreased ↑ Increased MCV ↓ Decreased ↑ Increased MCH ↓ Decreased ↑ Increased RDW ↑ Increased ↓ Decreased Ferritin ↓ Decreased ↑ Increased Iron ↓ Decreased ↑ Increased TIBC ↑ Increased ↓ Decreased UIBC ↑ Increased ↓ Decreased Transferrin ↑ Increased ↓ Decreased TSAT ↓ Decreased ↑ Increased

Causes of Increased or Decreased TIBC and the Effect of Treating Underlying Diseases on Iron Metabolism Parameters
TIBC (Total Iron Binding Capacity) represents the iron-binding capacity of Transferrin. An increase or decrease in TIBC is usually an indicator of an underlying physiological or pathological condition.
Therefore, treatment is directed toward the underlying cause of abnormal TIBC levels.

Low TIBC
Definition
A decreased TIBC indicates that the amount of Transferrin or the iron-carrying capacity of the blood is reduced.
Since Transferrin is produced in the liver, decreased TIBC is commonly observed in conditions such as:
• Chronic inflammation
• Liver diseases
• Malnutrition
• Kidney diseases
• Chronic infections
• Malignancies

1. Anemia of Chronic Disease (ACD)
One of the most common causes of low TIBC is Anemia of Chronic Disease.
Mechanism:
• Inflammation increases the level of the hormone Hepcidin.
• Hepcidin prevents the release of iron from body storage sites.
• Iron remains stored inside cells but is unavailable for red blood cell (RBC) production.

Laboratory Pattern:
Parameter Change Iron ↓ Decreased Ferritin ↑ Increased or Normal TIBC ↓ Decreased Transferrin ↓ Decreased TSAT ↓ Decreased
Treatment
Treatment focuses on controlling the underlying disease.
Anti-inflammatory or disease-controlling medications:
• Corticosteroids (in some inflammatory diseases)
• Biologic drugs in autoimmune diseases
• Antibiotics in chronic infections

Effect on Blood Tests
With control of inflammation:
Parameter Change Hb ↑ Increased Iron ↑ Increased TIBC ↑ Returns toward normal Ferritin ↓ Decreased CRP ↓ Decreased ESR ↓ Decreased
2. Liver Disease
Since Transferrin production occurs in the liver, liver damage can cause a reduction in transferrin levels.
Causes:
• Cirrhosis
• Hepatitis
• Liver failure

Treatment
Depending on the cause:
• Treatment of hepatitis
• Removal of liver-damaging factors
• Treatment of the underlying disease
• Correction of malnutrition

Effect on Laboratory Tests
With improvement in liver function:
Parameter Change Transferrin ↑ Increased TIBC ↑ Increased Albumin ↑ Increased Liver enzymes ↓ Decreased
3. Malnutrition and Protein Deficiency
Because Transferrin is a protein, reduced protein levels in the body lead to decreased transferrin production.
Causes:
• Inadequate protein intake
• Malabsorption
• Chronic diseases

Treatment:
• High-protein diet
• Nutritional supplements
• Treatment of underlying gastrointestinal disorders

Laboratory Effects:
Parameter Change Transferrin ↑ Increased TIBC ↑ Increased Albumin ↑ Increased Hb ↑ Increased
4. Chronic Kidney Disease (CKD)
In kidney disease:
• Erythropoietin production decreases.
• Red blood cell production decreases.
• Inflammation increases.
Medications Used:
Erythropoiesis Stimulating Agents (ESA)
Examples:
• Epoetin alfa
• Darbepoetin alfa
Sometimes used together with:
• Iron sucrose
• Ferric carboxymaltose

Effects on Blood Parameters:
Parameter Change Hb ↑ Increased RBC ↑ Increased Hct ↑ Increased Iron availability ↑ Increased
Medications That May Decrease TIBC
Medication Effect Corticosteroids May decrease TIBC Androgens Decrease Transferrin production Anti-inflammatory drugs May alter TIBC by reducing inflammation Chemotherapy drugs Reduce protein production
Does Iron Supplementation Increase TIBC?
No, not directly.
If a person has true iron deficiency, iron supplementation causes:
• ↑ Ferritin
• ↑ Serum Iron
• ↑ TSAT
• ↑ Hb
However, TIBC usually decreases or returns toward the normal range because the body no longer needs to increase Transferrin production to capture more iron.

Ferritin Management and Its Relationship with Iron Metabolism Parameters
Unlike TIBC, there is usually no medication prescribed specifically to increase Ferritin itself. Instead, treatment focuses on correcting the underlying cause of low or high Ferritin levels.
Ferritin represents the body’s iron storage level and is also considered an acute-phase inflammatory marker.

1. Low Ferritin
A low Ferritin level usually indicates depleted iron stores and is treated with iron supplementation.
Medications and Their Effects on Laboratory Parameters
Medication Effect on Laboratory Parameters Ferrous Sulfate ↑ Ferritin, ↑ Serum Iron, ↑ Hb, ↓ TIBC Ferrous Fumarate Increases iron stores and improves anemia Ferrous Gluconate Gradual increase in iron levels with fewer gastrointestinal side effects Iron Polymaltose Complex Increases stored iron; suitable for some patients who cannot tolerate oral iron Iron Sucrose / Ferric Carboxymaltose Rapid increase in Ferritin and Iron levels in severe deficiency or lack of response to oral iron
Expected Effects on Iron Panel After Iron Deficiency Treatment
Parameter Change After Treatment Ferritin ↑ Increased Serum Iron ↑ Increased TIBC ↓ Decreased Transferrin ↓ Decreased Hb and Hct ↑ Increased (if anemia is present) MCV / MCH ↑ Gradual increase 2. High Ferritin
In cases of elevated Ferritin, iron supplementation is usually not recommended. Treatment depends on the underlying cause.

A) Iron Overload (e.g., Hemochromatosis)
Medications / Treatments:
• Deferoxamine
• Deferasirox
• Deferiprone
Effects:
• ↓ Ferritin
• ↓ Body iron stores
• ↓ Serum Iron (in some conditions)
In addition, therapeutic phlebotomy (blood removal therapy) may be used to reduce excessive iron accumulation.

B) Increased Ferritin Due to Inflammation or Infection
Examples:
• Chronic diseases
• Infections
• Autoimmune diseases
Treatment:
Treatment focuses on the underlying condition:
• Antibiotics for infections
• Anti-inflammatory medications
• Disease-specific therapies

Typical Laboratory Pattern in These Conditions:
Parameter Change Ferritin ↑ Increased Serum Iron ↓ Decreased TIBC ↓ Decreased or Normal Transferrin ↓ Decreased
Important Point for Laboratory Interpretation
Classic Pattern:
Iron Deficiency:
• Ferritin ↓
• Iron ↓
• TIBC ↑
• Transferrin ↑

Inflammation / Chronic Disease:
• Ferritin ↑
• Iron ↓
• TIBC ↓
• Transferrin ↓

Iron Profile Interpretation Table
Clinical Condition Serum Iron TIBC Ferritin Transferrin Possible Interpretation Iron Deficiency Anemia ↓ Decreased ↑ Increased ↓ Decreased ↑ Increased Depletion of body iron stores; the most common cause of iron deficiency anemia Iron Deficiency Treatment with Supplements ↑ Increased ↓ Gradual decrease ↑ Increased ↓ Decreased Appropriate response to iron therapy Chronic Disease / Inflammation (Anemia of Chronic Disease) ↓ Decreased ↓ Decreased or Normal ↑ Increased or Normal ↓ Decreased Iron is present in body stores but its availability for erythropoiesis is reduced Sideroblastic Anemia ↑ Increased Normal or ↓ Decreased ↑ Increased Normal or ↓ Decreased Impaired utilization of iron for hemoglobin synthesis Hemochromatosis
(Iron Overload) ↑ Increased ↓ Decreased ↑↑ Markedly Increased ↓ Decreased Excessive accumulation of iron in the body Iron Toxicity ↑↑ Increased ↓ Decreased ↑ Increased ↓ Decreased Severe increase in serum iron and stored iron Chronic Blood Loss Anemia ↓ Decreased ↑ Increased ↓ Decreased ↑ Increased Gradual loss of iron (such as gastrointestinal bleeding or heavy menstrual bleeding) Acute Inflammation or Infection ↓ Decreased ↓ Decreased ↑ Increased ↓ Decreased Increased Ferritin due to the inflammatory response Liver Diseases ↑ or Normal Variable ↑ Increased ↓ or Normal Liver damage may cause release of stored Ferritin Malnutrition or Reduced Protein Synthesis ↓ or Normal ↓ Decreased ↓ or Normal ↓ Decreased Reduced production of Transferrin in the body Summary of Changes in Each Parameter
Test Meaning Causes of Increase Causes of Decrease Serum Iron Amount of circulating iron in the blood Iron overload, hemolysis, some liver diseases Iron deficiency, inflammation, chronic disease TIBC Iron-binding capacity of Transferrin Iron deficiency, chronic blood loss Inflammation, liver disease, malnutrition Ferritin Body iron storage + inflammatory marker Inflammation, iron overload, liver disease Depletion of iron stores
(most important indicator of iron deficiency) Transferrin Iron transport protein Iron deficiency Inflammation, liver disease, malnutrition