Persistent tiredness, weakness, or shortness of breath can sometimes signal anaemia. When iron levels stay low without an obvious explanation, hidden bleeding in the digestive tract may be one possible cause. Timely investigation can help identify the reason for iron loss and guide treatment, even when no blood is visible in the stool.

Iron-deficiency anaemia has several possible causes, including heavy menstrual bleeding, low dietary intake and increased iron needs. When it is unexplained or returns after treatment, a gastrointestinal cause may need to be considered.

What Is Iron-Deficiency Anaemia?

Iron is essential for producing haemoglobin, the protein in red blood cells responsible for carrying oxygen throughout the body.

Without enough iron, the body cannot make adequate haemoglobin and healthy red blood cells.

Symptoms may develop slowly and can initially be mild. They may include:

• Persistent tiredness or weakness
• Shortness of breath
• Dizziness or light-headedness
• Headaches
• Pale skin
• Heart palpitations or a faster heartbeat
• Reduced exercise tolerance
• Cold hands and feet
• Difficulty concentrating

Some people notice few symptoms.

A healthcare professional will typically assess haemoglobin levels together with iron studies. Ferritin is particularly useful because it reflects the body’s iron stores, although interpretation may be more complicated in people with inflammation or chronic illness.

Replacing iron matters, but identifying why the deficiency developed is also part of treatment.

What Causes Iron Deficiency?

Iron deficiency can occur when the body loses iron, does not consume enough iron, cannot absorb it properly or requires more iron than usual.

Common causes include heavy menstrual bleeding, pregnancy, inadequate dietary intake, frequent blood donation and poor iron absorption.

Conditions such as celiac disease and inflammatory bowel disease may contribute to iron deficiency by affecting the intestine’s ability to absorb nutrients.

Another possible cause is chronic blood loss. When bleeding from the digestive tract is too small to see, it is called occult gastrointestinal bleeding. Repeated small losses can deplete iron stores over time.

How Can Gastrointestinal Bleeding Remain Hidden?

Gastrointestinal bleeding does not always mean obvious red blood in the stool or vomiting blood. It may be microscopic and occur slowly. A fall in haemoglobin or ferritin may be the first clue.

Bleeding can originate anywhere from the oesophagus and stomach to the small intestine, colon or rectum.

Possible causes include peptic ulcers, inflammation, abnormal blood vessels, polyps, inflammatory bowel disease and gastrointestinal tumours. Certain medications, particularly non-steroidal anti-inflammatory drugs such as ibuprofen and aspirin, can also increase the risk of gastrointestinal irritation, ulcers and bleeding in susceptible patients.

Persistent or recurrent anaemia deserves a review of the cause as well as iron replacement.

When Should the Gastrointestinal Tract Be Investigated?

The appropriate investigation depends on the patient’s age, sex, symptoms, medical history, family history, blood results and other possible causes of iron deficiency.

Menstrual blood loss is an important consideration, but it should not automatically be assumed to explain every case. Symptoms, blood results and preferences help shape an individual decision.

Blood testing may also be used to investigate conditions such as coeliac disease, and testing for Helicobacter pylori may be appropriate in selected patients.

Gastroscopy: Examining the Upper Digestive Tract

A gastroscopy, also known as an upper endoscopy, allows the gastroenterologist to examine the oesophagus, stomach and duodenum.

A thin, flexible endoscope containing a camera is passed through the mouth while the patient is appropriately sedated.

During the examination, the doctor can look for abnormalities that may explain blood loss or iron deficiency, including:

• Peptic ulcers
• Gastritis or inflammation
• Oesophageal abnormalities
• Tumours or other abnormal growths
• Sources of active or previous bleeding

Biopsies can also be taken when necessary, and certain bleeding lesions may sometimes be treated during the procedure.

Colonoscopy: Looking for Lower Gastrointestinal Causes

A colonoscopy examines the lining of the colon and rectum using a flexible camera inserted through the rectum.

When investigating unexplained iron-deficiency anaemia, colonoscopy can help identify possible causes of chronic blood loss such as polyps, inflammation, vascular abnormalities and colorectal cancer.

One advantage of colonoscopy is that suspicious areas can be biopsied during the procedure. Polyps may also be removed depending on their size and characteristics.

The presence of iron-deficiency anaemia does not automatically mean that a serious gastrointestinal disease is present. However, investigating unexplained anaemia appropriately is important because some gastrointestinal conditions can remain relatively silent during their early stages.

What Happens When Gastroscopy and Colonoscopy Do Not Find the Cause?

The gastrointestinal tract is extensive, and a significant portion of the small intestine cannot be adequately examined using conventional gastroscopy or colonoscopy.

If initial investigations do not identify a source of blood loss, the next step depends on the individual clinical situation.

For uncomplicated patients without symptoms whose initial investigations are negative, a trial of iron replacement and follow-up may come before routine capsule endoscopy.

However, persistent or recurrent iron-deficiency anaemia, continued evidence of gastrointestinal blood loss or other concerning findings may warrant further investigation of the small intestine.

Capsule Endoscopy: Seeing the Small Intestine

Capsule endoscopy is particularly valuable because it allows the small bowel to be visualised without conventional scope insertion.

The patient swallows a capsule containing a miniature camera. As the capsule moves naturally through the gastrointestinal tract, it captures thousands of images of the small-intestinal lining.

The images are recorded for review by the gastroenterologist. The capsule takes pictures but cannot take biopsies or treat a bleeding lesion.

Capsule endoscopy can help identify small-bowel abnormalities that may otherwise be difficult to detect, including areas of inflammation, abnormal blood vessels, ulcers, polyps, or other lesions associated with bleeding.

Double-Balloon Enteroscopy: Investigating and Treating the Small Bowel

If capsule endoscopy or another investigation identifies an abnormality deeper within the small intestine, double-balloon enteroscopy may sometimes be recommended.

This specialised endoscopic technique enables the gastroenterologist to travel much further through the small bowel than standard gastroscopy or colonoscopy.

Double-balloon enteroscopy may be used to obtain biopsies, investigate suspected small-bowel bleeding, remove selected polyps, treat certain bleeding lesions or manage strictures.

It is useful when a finding needs a biopsy or direct treatment.

Dr Eduan Deetlefs has a particular clinical interest in obscure gastrointestinal bleeding and provides small-bowel investigation including capsule endoscopy and double-balloon enteroscopy at GI Doc Cape Town.

Treating Iron Deficiency Means Treating the Cause

Iron replacement remains an important part of managing iron-deficiency anaemia, but replacing iron alone may not solve the problem if blood loss continues.

Treatment depends on the diagnosis.

Some patients may respond well to oral iron supplementation. Others may require intravenous iron when oral treatment is poorly tolerated, ineffective or unsuitable for their clinical situation.

When a gastrointestinal source is identified, treatment may involve medication, removal of polyps, treatment of inflammation or endoscopic management of a bleeding lesion. Endoscopic techniques may sometimes allow a gastroenterologist to diagnose and treat a bleeding area during the same procedure.

Follow-up blood tests help confirm that haemoglobin and iron stores are recovering.

Warning Signs That Should Not Be Ignored

Seek medical assessment if symptoms of anaemia persist, particularly when they occur together with unexplained weight loss, persistent abdominal discomfort, a change in bowel habits or recurrent gastrointestinal symptoms.

Visible blood in the stool, black or tarry stools and vomiting blood require prompt medical assessment. Severe dizziness, fainting, rapid heartbeat, confusion or other symptoms suggesting significant blood loss require urgent medical attention.

Conclusion

Iron-deficiency anaemia can have many causes, and not every patient will require extensive gastrointestinal investigation. However, when iron deficiency is unexplained, recurrent or does not respond as expected to treatment, investigating the digestive tract may help identify an underlying condition that would otherwise remain unnoticed.

Gastroscopy and colonoscopy allow examination of the upper and lower gastrointestinal tract, while capsule endoscopy and double-balloon enteroscopy provide additional options when the small intestine needs to be investigated.

The goal is not simply to replace lost iron but, where possible, to determine why the iron deficiency developed and treat the underlying cause.

Dr Eduan Deetlefs has a special interest in inflammatory bowel disease and iron-deficiency anaemia related to obscure intestinal bleeding and provides diagnostic and therapeutic gastroenterology services in Cape Town.

To arrange a consultation with Dr Eduan Deetlefs at GI Doc Cape Town get in contact:

Tel: 021 202 0626
Email: info@gidoc.co.za
Address: Suite 304, 3rd Floor, The Park Building, Park Road, Pinelands, Cape Town