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IDA — iron-deficiency anemia

Iron-deficiency anemia

Iron atoms, the protein ferritin and pale, small red blood cells

Iron-deficiency anemia (IDA) is the most common type of anemia. It develops when iron stores are not enough to produce hemoglobin, and the red blood cells come out small and pale.

IDA is the end point of prolonged iron deficiency: first the stores are depleted (ferritin falls), and only then does hemoglobin decline.

Why IDA develops

There are three causes: blood loss (heavy periods, hidden gastrointestinal bleeding, including from ulcers, tumors and NSAID use), insufficient intake or absorption of iron (a poor diet, celiac disease, Crohn's disease, stomach surgery) and increased demand (pregnancy, breastfeeding, rapid growth). In men and postmenopausal women, IDA calls for a search for a source of blood loss until proven otherwise.

How it shows up

Besides general weakness, pallor and shortness of breath, iron deficiency has specific signs: brittle, spoon-shaped nails, hair loss, cracks at the corners of the mouth, a distorted appetite (pica, a craving to chew ice) and restless legs syndrome. These symptoms can appear even before hemoglobin drops.

Diagnosis and treatment

The key marker of iron stores is ferritin; in IDA it is low, and transferrin saturation is reduced. Treatment is oral iron supplements (usually 6 weeks until hemoglobin normalizes and several more months to replenish stores); for intolerance or severe deficiency, intravenous iron is used. The cause of iron loss must always be addressed.

Reference ranges

Laboratory reference points in iron-deficiency anemia:

Ferritin< 30 ng/mL (clear deficiency < 15 ng/mL)
Transferrin saturation< 20%
MCV< 80 fL (microcytosis)
MCH< 27 pg (hypochromia)
Important: Ferritin is an acute-phase protein: with inflammation, infection or liver disease it rises and can mask a deficiency. In that case, one relies on transferrin saturation and the level of inflammation.

Calculate using this marker

Calculators where IDA is used directly:

Iron Calculator Interpret your labs: ferritin, hemoglobin, and transferrin saturation Open Iron Deficiency Test 13 scientifically validated questions — assess your risk in 3 minutes Open

Frequently asked questions

Ferritin is low but hemoglobin is normal — is that IDA?

No, that is latent (hidden) iron deficiency: the stores are already depleted, but there is no anemia yet. This is an early stage at which treatment is especially effective and prevents IDA from developing.

How should you take iron tablets correctly?

Usually on an empty stomach or between meals, ideally with a source of vitamin C for absorption. Coffee, tea, dairy products and antacids reduce absorption. A doctor selects the tolerability and dose.

Related terms

Iron deficiency A shortage of iron in the body Ferritin The iron-storage protein of the body Transferrin The iron-transport protein of the blood Transferrin saturation The proportion of transferrin loaded with iron TIBC Total iron-binding capacity of the serum Hemoglobin The oxygen-carrying protein of red blood cells Microcytosis A reduction in the size of red blood cells MCV Mean corpuscular volume — the size of red blood cells MCH (Mean corpuscular hemoglobin) How much hemoglobin a single red blood cell carries, in picograms Iron absorption The uptake of iron in the intestine Pica A pathological craving for inedible substances Restless legs syndrome Unpleasant sensations in the legs at night Celiac disease Autoimmune gluten intolerance

Sources

  1. American Society of Hematology — Iron-Deficiency Anemia
  2. MedlinePlus — Iron deficiency anemia
  3. StatPearls (NCBI) — Iron Deficiency Anemia
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This content is educational and does not replace consultation with a physician. Reference ranges may vary depending on the laboratory and method — rely on the ranges stated on your own test report.
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