Iron Deficiency Anaemia – A Gastroenterology Perspective

Written by A/Prof Viraj Kariyawasam, Gastroenterologist

1. What is Iron Deficiency Anaemia?

Iron deficiency anaemia occurs when the body does not have enough iron to produce healthy red blood cells, leading to reduced oxygen delivery to tissues. From a gastroenterology perspective, iron deficiency anaemia is a key clinical finding that often signals underlying gastrointestinal blood loss or malabsorption.

In adult men and postmenopausal women, iron deficiency anaemia should always be investigated for a gastrointestinal cause until proven otherwise.

2. Gastrointestinal Causes of Iron Deficiency Anaemia

The gastrointestinal tract is the most common source of iron loss in adults. Iron deficiency may result from chronic, often occult, blood loss or impaired absorption.

Common gastrointestinal causes include bowel polyps, bowel cancer, upper gastrointestinal ulcers, erosive gastritis, oesophagitis, inflammatory bowel disease, and angiodysplasia. Chronic use of medications such as non-steroidal anti-inflammatory drugs can contribute to bleeding.

Malabsorption is another important cause and may occur in conditions such as coeliac disease, atrophic gastritis, or after certain gastrointestinal surgeries.

3. Symptoms & How It May Present

Symptoms of iron deficiency anaemia may be non-specific and develop gradually.

Common symptoms include fatigue, reduced exercise tolerance, shortness of breath, dizziness, headaches, palpitations, and poor concentration. Some patients present with iron deficiency on routine blood tests before symptoms become apparent.

4. How Is It Investigated?

Initial blood tests confirm iron deficiency, typically showing low haemoglobin and low ferritin. Additional blood tests may assess inflammation and exclude other causes of anaemia.

From a gastroenterology perspective, investigation focuses on identifying a bleeding or malabsorptive source. This commonly includes gastroscopy and colonoscopy, even in the absence of gastrointestinal symptoms, particularly in men and postmenopausal women.

If upper and lower endoscopy are normal and iron deficiency persists, further investigations such as capsule endoscopy, imaging, or specialised blood tests may be required to assess the small bowel.

5. Treatment & Management Options

Management involves treating the underlying gastrointestinal cause and replenishing iron stores.

Iron replacement may be given orally or intravenously, depending on severity, tolerance, and ongoing blood loss. However, iron supplementation alone is not sufficient without identifying and managing the underlying cause.

6. Follow-Up and Long-Term Management

Follow-up blood tests are essential to confirm recovery of iron stores and haemoglobin.

Ongoing surveillance may be required in patients with identified gastrointestinal pathology, such as polyps, inflammatory bowel disease, or vascular lesions, to prevent recurrence.

7. Prevention & Risk Reduction

Early recognition and investigation of iron deficiency anaemia reduces the risk of missed gastrointestinal disease.

In adults, repeated iron supplementation without investigation should be avoided, as this may delay diagnosis of serious underlying conditions.

8. When to Seek Medical Advice

Medical review is recommended for unexplained iron deficiency or anaemia, particularly in adult men and postmenopausal women.

Urgent investigation is required if iron deficiency anaemia is associated with weight loss, gastrointestinal bleeding, or other alarm symptoms.