Iron Deficiency vs. Anaemia: Are they the same?

11 Nov 2025

Feeling dizzy, tired, or breathing shortness on a daily basis are often easily dismissed off as just a sign of busy lifestyle. Yet in many circumstances, these may be symptoms of something more serious –in most cases they commonly point to anaemia or iron deficiency. Although the two terms are often used interchangeably, conventionally they are not the same thing. It is important to know the difference between the two, as it can impact how it is diagnosed and treated.

Both anaemia and iron deficiency are relatively common in the UK, especially amongst females, teenagers, older adults, and vegetarians. According to the NHS, iron deficiency is the most common nutritional deficiency in the world, and anaemia can impact as many as 1 in every 10 women in their reproductive years. While it is common, symptoms often develop gradually which makes anaemia or iron deficiency easy to miss until fatigue creeps in.

In this blog, we will explain how iron deficiency and anaemia differ, the early warning signs of both, how to diagnose them, and what their potential treatment options can be.

What is Iron Deficiency?

Iron is a vital mineral required for the synthesis of haemoglobin – the protein present in red blood cells that transport oxygen around the body. If you don’t have sufficient iron, your body cannot produce enough haemoglobin. As a consequence, some of your organs and tissues won’t receive enough oxygen, leading you to feel weak and tired.

Iron deficiency means that your body has low iron stores – assessed with ferritin and some other markers. In the early stages of iron deficiency, the red blood cell count can still be normal. This stage can be called iron deficiency without anaemia. If the iron deficiency is not treated, it can progress to iron deficiency anaemia (IDA). During IDA, the red blood cells are smaller and paler than usual due to insufficient haemoglobin being produced in the red blood cells.

Common Factors Leading to Iron Deficiency in the UK

Several lifestyle and medical factors can lead to lower levels of iron:

• Blood loss: The most common cause in adults is blood loss from heavy menstrual bleeding, ulcers, inflammatory bowel disease or gastrointestinal loss.
• Insufficient dietary iron intake: If people consume little meat, fish or fortified cereals, this may be seen.
• Increased requirements: For example, prompting pregnancy, the body requires more iron for the growing baby.
• Reduced absorption: Disorders like coeliac disease, gastritis or even surgery on your stomach can affect the absorption of iron.
• Chronic conditions: Some inflammatory disorders can interfere with the way you use and store iron.

NHS guidance recommends investigating the cause of iron deficiency in all adult men and post-menopausal women (and anyone with red-flag features), not just those over 50, as GI blood loss must be excluded.

What is Anaemia?

Anaemia is an umbrella term – it refers to having a lower number of red blood cells or less haemoglobin than normal, which reduces the blood’s capacity to carry oxygen. There are many forms of anaemia, and the most common type in the UK is iron deficiency anaemia, but it is not the only type.

Common Forms of Anaemia

1. Iron deficiency anaemia (IDA) – Caused by a lack of iron.
2. Vitamin B12 or Folate Deficiency Anaemia– Caused by a lack of B vitamins, with vitamin B12 deficiency commonly associated with vegan diets and lack of absorption via digestion.
3. Anaemia of Chronic Disease– Occurs with long-standing diseases, such as chronic infection or rheumatoid arthritis.
4. Haemolytic Anaemia – Occurs when the rate of destruction of red blood cells overpowers the rate of production of new RBCs in the body.
5. Aplastic anaemia - A rare but serious condition in which the bone marrow cannot produce sufficient blood cells.

While it is true that iron deficiency can result in anaemia, it is not valid to assume that iron deficiency is the only cause of anaemia. This distinction is essential, since treatment depends on the underlying cause of the blood abnormality.

Key Differences between Iron Deficiency and Anaemia    

Overall, iron deficiency is the cause, and anaemia is the effect – but not in all cases.

Signs to Look Out For

Signs of iron deficiency and anaemia can appear to be similar, however, the two conditions have some slight differences which may help you distinguish between them.

Common Signs of Iron Deficiency

• Constant fatigue or tiredness
• Pale or shallow skin
• Brittle or spoon-shaped nails
• Dry hair, loss of hair, or hair thinning
• Cravings for non-edible items, such as paper, clay or ice – this is called pica
• Restless leg syndrome or tingling legs
• Trouble with concentration

Symptoms of Anaemia (once the deficiency is more severe)

• Shortness of breath with even slight physical exertion
• Feeling dizzy or light headed
• Very rapid heart rate or irregular cardiac rhythm and palpitations
• Headaches or blurriness in vision
• Cold hands and feet
• Chest pain – in elderly or patients with day-to-day conditions

As the body gradually adapts, many individuals with mild anaemia may not know they have it until their levels of haemoglobin drop to a dramatically lower level. This is why routine screening is important, particularly forhigh-risk groups.

Who are more at Risk?

Certain groups are at increased risk of developing iron deficiency or anaemia in the UK:

• Women of reproductive age– A common cause of iron deficiency is heavy periods.
• Pregnant women –The developing foetus has an increased iron demand.
• Infants and young children–There is a higher demand for iron due to rapid growth.
• Vegetarians and vegans– Plant-based diets offer non-haem iron that is less efficiently absorbed.
• Older adults– More likely to have chronic disease or possible blood loss from the gut.
• People with digestive disorders–Crohn’s disease, Coeliac disease, and ulcerative colitis may impair absorption.
• Frequent blood donors– Loss of iron occurs everytime you donate blood.

Acknowledging these risk factors is crucial to determine when to look for early indicators of deficiencies.

How is the diagnosis of anaemia and iron deficiency performed?

In the UK, anaemia and iron deficiency diagnoses are clear and straightforward.

Blood tests usually include:

• Full Blood Count (FBC): This assesses haemoglobin, size of red blood cells (MCV), and other indicators of anaemia.
• Serum Ferritin: Reflects iron stores in the body – low ferritin levels accurately suggest iron deficiency.
• Serum Iron, Transferrin, and Total iron-binding capacity (TIBC): Provide greater detail about the efficiency of transport and utilisation of the iron.
• B12 and Folate levels: Rule out other causes of anaemia.             

Additionally, doctors may check thyroid and kidney function, as in certain situations systemic disease may mimic features of anaemia.

If testing confirms iron deficiency, further tests may be warranted to investigate the underlying cause, such as gastrointestinal investigations to check for malabsorption or bleeding.

If you want results more quickly, many private clinics in London provide anaemia blood test in London with same-day results and assessment by a medical professional.

How are these conditions treated?

Treatment can vary based on the degree of deficiency and its underlying cause.

Iron Deficiency (without anaemia)

• Oral Iron Supplements: Typically ferrous sulphate or ferrous fumarate tablets are usually continued over several months.
• Dietary Changes:
• Eat foods rich in iron like poultry, red meat, lentils, fish, spinach, beans, and fortified cereals.
• Take with some vitamin C (such as strawberries, orange juice, peppers ) to help with absorption.
• Do not take tea or coffee around meal times since the tannins inhibit iron absorption.
• Address the Cause: Treating ulcers, heavy periods, or dietary problems should help maintain iron levels at normal.

Iron Deficiency Anaemia

• Stronger Iron Therapy: In cases of oral intolerance or ineffectiveness to oral supplements, you may require higher doses or intravenous iron.
• Blood Transfusions: Transfusions are generally reserved for severe and/or haemodynamically unstable, symptomatic anaemia, or specific indications; otherwise iron replacement is preferred.
• Follow-up Blood Work: After about 3 months to check if haemoglobin and ferritin have been restored.

Anaemia Due To Other Causes

If you are anaemic due to vitamin B12 or folate deficiency, you will be prescribed injections or supplements. For anaemia from chronic illness, it is necessary to treat the underlying medical condition and not just supplement the nutrients.

Preventing Anaemia and Iron Deficiency

While not every case is preventable, lifestyle and eating habits significantly influence your ability to reduce risk.

Some tips:

• Have a balanced diet including both haem iron (animal sources) and non-haem iron (plant sources)
• Don’t ignore your health checks – a full blood count will identify deficiencies early
• Women with heavy bleeding and scheduling life changes, should talk to the physician about preventative iron supplements
• Always follow medical advice about taking supplements such as iron – too much iron can be harmful
• Look after your digestive health and get treatment for ulcers, heartburns, or inflammatory bowel disease
• Routine antenatal screening for anaemia (FBC) is offered at booking and again at ~28 weeks; iron studies/supplementation are targeted, not universally ‘compulsory’.

Healthy iron levels improve not only your overall energy levels, but also your cognitive and immune function.

When to See a Doctor

You should see your GP or another healthcare professional if you experience:

• Continuous tiredness, pale skin, or breathing difficulties
• Heavy menstrual bleeding
• Cravings for non-food or non-edible substances
• Noticeable dizziness orheart palpitations
• Indigestion that continues to be digestive issues (which lead to hidden blood loss)

Iron deficiency anaemia can put strain on your heart, lead to complications in pregnancy, and reduced immunity if not treated.Getting checked with a blood test is easy to assess if you have low iron, and improving your deficiency can result in a quick recovery.

Interpreting Test Results

When you review your blood test results, you may see the following:

Doctors interpret these results in relation to your medical history to confirm if it is simply a deficiency, or part of something more complicated.

Outlook and Recovery

The good news is that most individuals experience a positive response to treatment once the right diagnosis is made. Iron supplements restore energy levels typically within weeks; however, restoring iron to blood stores may take up to several months.

The key to sustained improvement is to identify the initial reason for the deficiency –heavy menstrual bleeding, dietary habits, or gastrointestinal disturbances. Without addressing the underlying cause, the deficiency is likely to return.

Regular monitoring over time with a healthy diet and proper follow up with your clinician can help to maintain stable iron and haemoglobin levels in the long run.

Summary: Anaemia vs. Iron Deficiency in a Nutshell

• Iron deficiency suggests low stores of iron
• Anaemia indicates low red blood cell count or haemoglobin – iron deficiency is just one of the potential causes of blood control
• You may have iron deficiency without anaemia
• Early symptoms of deficiency include pale skin, fatigue, and poor concentration
• Diagnosis is done through a blood test by assessing haemoglobin, ferritin and other markers for iron
• Treatment approaches to iron deficiency depend on the cause – dietary changes, iron supplements or medical actions may be appropriate

Understanding the difference between iron deficiency and anaemia is useful to ensure you receive appropriate treatment, and avoid unnecessary fatigue or other complications.

Final Thought

If you feel unusual tiredness, shortness of breath, or think that your diet may not have adequate iron, a simple blood test would be worthwhile.

Our private clinicians at South Kensington MD provide same-day blood tests and discussion of results, along with a professional plan to safely and effectively restore healthy iron levels.