A deficiency of iron can result from a number of different causes. Inadequate iron in the diet, impaired absorption of iron, and excessive bleeding are all examples of conditions that can lead to iron deficiency.
The amount of iron in the body is tightly regulated by cells of the intestine that can increase or decrease iron absorption according to need. When iron deficiency becomes severe, the manufacture of red blood cells is decreased, and iron deficiency anemia results.
Symptoms of iron deficiency
- Fatigue
- Leg cramps
- Cold intolerance
- Infections
- A craving for ice or non-food items (pica)
- Lightheaded feelings
- Shortness of breath
- Altered behavior
- Poor performance in school
- Difficulty swallowing
- Sore tongue
When examined by a physician, a patient with iron deficiency might also show the presence of
- Pallor
- Spoon-shaped nails
- A glossy tongue
- Fissures at the corners of the mouth
- Enlargement of the spleen
- In infants, growth may be impaired
Causes of iron deficiency
Certain illnesses and conditions can increase the risk of iron deficiency.
Loss of iron through bleeding can occur with:
- Extremely heavy menstrual periods
- Cancer of the esophagus, bowel, stomach, or colon
- Esophageal varices
- Gastrointestinal bleeding caused by aspirin or ibuprofin
- Peptic ulcer disease
Disorders of iron absorption that cause iron deficiency include:
- Celiac disease
- Gastric bypass
- Crohn’s disease
- Excessive use of antacids
In addition, vegetarians and older adults who do not eat a balanced diet may not get enough dietary iron and are at increased risk.
Tests for iron deficiency
Iron levels are normally tested through hematocrit and hemoglobin counts. Hematocrit measures the percentage of blood that consists of red blood cells. A normal result for men is in the range of 40.7% to 50.3%. For women, the normal range is 36.1% to 44.3%.
A test for hemoglobin shows how much hemoglobin is the blood. Normal levels for men are 13.8 to 17.2 grams per decaliter (g/dL). For women, the normal range is 12.1 to 15.1 g/dL.
Additional tests that may be ordered include:
- Bone marrow biopsy
- Serum iron level
- Iron binding capacity
- RBC indices
- Serum ferritin
Iron deficiency and pregnancy
Some degree of iron deficiency anemia is normal during pregnancy as the blood volume increases, resulting in some dilution of the blood. With tests that measure concentration of iron, such as hematocrit or hemoglobin, the numbers will be reduced even though the total amount of iron in the body is unchanged.
Therefore, anemia in a pregnant patient is sometimes defined as a hemoglobin value lower than 10.5 g/dL, rather than the usual minimum of 13-14 g/dL.
It is not uncommon that a woman does not have sufficient iron stores to support a pregnancy. Iron supplements are often prescribed for pregnant women for this reason. Iron deficiency anemia in pregnancy can cause preterm delivery, increased risk of perinatal mortality, and postpartum depression. For the baby, low birth weight and poor development are potential consequences.
Treatment of iron deficiency
Iron deficiency anemia is typically treated with oral supplements and a diet of iron-rich foods. Supplements may occasionally need to be given intravenously.
The prognosis for otherwise healthy patients is excellent. The hematocrit typically returns to normal in two months, and supplements should be continued for an additional 6 to 12 months to replenish the body’s iron stores.
Further Reading
How the gut microbiome supports iron uptake by intestinal regulatory T-cells