Iron deficiency is extremely common in India – yet the tests used to diagnose it are frequently misunderstood. Many people get a serum iron test when they should be getting a ferritin test, or receive a haemoglobin result and assume it tells the whole story about their iron status. Knowing which test to ask for and what each result tells you can mean the difference between catching iron deficiency early and missing it until it becomes anaemia.
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What Is Ferritin?
Ferritin is a protein that stores iron inside cells – primarily in the liver, spleen, and bone marrow. A small amount circulates in blood, and its concentration is directly proportional to total body iron stores. Think of ferritin as your body’s iron warehouse: when stores are full, ferritin is high; when depleted, ferritin is low – even if iron currently circulating in blood appears normal.
FERRITIN REFERENCE RANGES: Men 12-300 ng/mL | Women 12-150 ng/mL | Iron depletion threshold: below 30 ng/mL even with normal haemoglobin | Severe depletion: below 12 ng/mL. Note: Ferritin is also an acute-phase reactant – it rises during inflammation, infection, and liver disease, potentially masking iron deficiency.
What Is Serum Iron?
Serum iron measures iron currently circulating in the blood – specifically, iron bound to a transport protein called transferrin. Unlike ferritin, serum iron fluctuates significantly throughout the day based on recent diet.
SERUM IRON REFERENCE RANGE: 60-170 mcg/dL. Serum iron alone is an unreliable marker of iron deficiency – it varies by up to 30% within the same individual on different days and can appear normal even when stores are depleted.
TIBC and Transferrin Saturation
TIBC (Total Iron Binding Capacity) normal: 240-450 mcg/dL – rises above 450 in iron deficiency as the body produces more transferrin. Transferrin Saturation: (Serum Iron / TIBC) x 100. Normal: 20-50%. Below 20% = iron deficiency. Below 15% = significant deficiency.
Ferritin vs Serum Iron: Which Should You Test?
For most people with symptoms of iron deficiency – fatigue, hair fall, pallor – the most useful tests are:
Ferritin – the most sensitive marker of total iron stores and early depletion
Full iron panel (ferritin + serum iron + TIBC + transferrin saturation) – the most complete assessment
Haemoglobin or CBC – confirms whether iron deficiency anaemia has developed
Serum iron alone is rarely recommended as a standalone iron deficiency test due to its day-to-day variability.
When Ferritin Can Be Misleading
Ferritin rises during active inflammation, infection, liver disease, or cancer – independent of iron stores. Someone with low iron stores but active inflammation may have a falsely normal or elevated ferritin. In this situation, ferritin should be interpreted alongside inflammatory markers (CRP or ESR).
Frequently Asked Questions
Q1. What is the difference between ferritin and serum iron?
Ferritin measures total iron stores – reflecting body reserves accumulated over weeks to months. Serum iron measures only iron currently circulating in the blood, which fluctuates based on recent diet. Ferritin is the more sensitive and reliable marker for detecting iron deficiency at an early stage.
Q2. What is a normal ferritin level?
Normal ferritin is 12 to 300 ng/mL for men and 12 to 150 ng/mL for women. A ferritin below 30 ng/mL indicates iron store depletion even when haemoglobin is still normal – the clinical threshold most widely used to identify early iron deficiency before anaemia develops.
Q3. Can I have low ferritin but normal haemoglobin?
Yes. Iron depletion (low ferritin) precedes iron deficiency anaemia (low haemoglobin) by months. The body prioritises haemoglobin production while depleting ferritin. You may experience fatigue, hair fall, and reduced stamina with a normal haemoglobin level but depleted ferritin.
Q4. Which is better – ferritin or serum iron?
For screening, ferritin is better because it reflects total body iron stores rather than what is circulating on a given day. Serum iron varies up to 30% within the same person depending on recent diet and time of day. For a complete assessment, a full iron panel (ferritin + serum iron + TIBC + transferrin saturation) is ideal.
Q5. When can ferritin be falsely normal even when iron stores are low?
Ferritin is an acute-phase reactant – it rises during active inflammation, infection, liver disease, or cancer, independent of iron stores. In this situation ferritin may appear normal or elevated despite low iron. It should be interpreted alongside inflammatory markers (CRP or ESR).
Q6. Where can I get a ferritin test done at home in Pune?
FITTR Labs includes ferritin as part of the vitamins panel in the full body checkup. Standalone ferritin and full iron panel testing are available with home blood sample collection across all 10 FITTR Labs locations in Pune.
