Iron-deficiency anaemia (IDA) is one of the most common findings on routine blood tests, often flagged during check-ups for tiredness, breathlessness, or a general feeling of being run down. While the underlying cause is frequently dietary or related to menstrual blood loss, in some patients, especially older adults, IDA can be a red flag for something more serious.
A recent Scottish study from the University of Dundee has reinforced just how important it is to take iron-deficiency anaemia seriously, particularly when it’s found in patients with bowel-related symptoms.
Here, we’ll explore the link between iron-deficiency anaemia and bowel cancer, alongside the role of the FIT test and combined risk assessment in detection.
Understanding the link between IDA and Bowel Cancer
Iron is essential for producing haemoglobin, the part of red blood cells that carries oxygen around the body. When iron levels drop, haemoglobin falls, leading to symptoms like fatigue, weakness, pale skin, dizziness, and shortness of breath.
In people over the age of 50, especially those experiencing changes in their bowel habits, iron deficiency should never be dismissed. One of the most common causes of IDA in older adults is chronic blood loss from the gastrointestinal tract. In the context of bowel cancer, this bleeding is often slow and painless, going unnoticed in day-to-day life.
Over time, even small amounts of bleeding from a bowel tumour can lead to a significant drop in iron stores. That’s why unexplained anaemia is considered a ‘red flag’ symptom, and why further investigation is almost always warranted.
The role of the FIT test
The Faecal Immunochemical Test (FIT) is now widely used across the UK as a frontline tool for assessing bowel symptoms. It detects tiny amounts of blood in the stool that may not be visible to the naked eye. While not diagnostic in itself, a positive FIT result can point towards the need for further investigation, usually via colonoscopy.
What the recent Scottish study shows is that using FIT in combination with age and iron-deficiency status provides a far more accurate assessment than any single factor alone. Patients with all three risk indicators including positive FIT, older age, and iron-deficiency anaemia, were found to be at significantly higher risk of harbouring colorectal cancer.
Meanwhile, those with normal iron levels and a negative FIT were far less likely to have cancer, even if they were experiencing bowel symptoms.
The research found that combining faecal haemoglobin levels (from the FIT test), patient age, and iron-deficiency anaemia status dramatically improved the ability to identify those at higher risk of colorectal cancer.
Anaemia should never be ignored
Too often, iron-deficiency anaemia is treated with supplements without exploring why the deficiency is there in the first place. While iron tablets may correct the lab result, they can mask a problem that hasn’t been properly addressed.
If IDA is found, particularly in men or postmenopausal women, it’s essential to rule out gastrointestinal causes. That may include a colonoscopy, endoscopy, or additional imaging, depending on the individual case. Catching bowel cancer early, when it’s small and hasn’t spread, can make a dramatic difference to treatment options and survival rates.
Even when cancer isn’t the cause, other gastrointestinal conditions like ulcers, polyps, or inflammatory bowel disease (IBD) may be contributing to iron loss and need attention.
A targeted approach to bowel symptoms
At the Warwick Bowel and Hernia Clinic, we see many patients referred with vague but persistent symptoms like fatigue, bloating, abdominal discomfort, or changes in bowel habit. In some cases, it’s a combination of subtle clues, like a mild anaemia and a borderline FIT result, that lead us to the right diagnosis.
Iron-deficiency anaemia should never be viewed in isolation, especially when bowel symptoms are present. By considering multiple factors together, we can identify high-risk patients sooner, reduce unnecessary delays, and improve outcomes through early detection.
If you’ve been told you have low iron and you’re experiencing bowel changes or unexplained fatigue, don’t brush it off. Get in touch to book an appointment with Mr Michael Stellakis for a consultation.
