Vitamin B12 Deficiency: Symptoms, Causes, and Detection

Vitamin B12 is an essential vitamin that the body needs to make healthy red blood cells, support normal nerve function, and help produce DNA. When the body does not have enough vitamin B12, it can lead to vitamin B12 deficiency, which may cause anemia as well as other health problems.

Vitamin B12 deficiency can develop gradually, and its symptoms may be mild at first. Early detection and appropriate treatment can help prevent complications, particularly those affecting the nervous system.

Vitamin B12 Deficiency and Anemia

Anemia does not always mean that a person has iron deficiency. It can have many different causes, including blood loss, chronic diseases, inherited blood disorders, and deficiencies of vitamins such as B12 and folate.

When vitamin B12 levels are low, the body may have difficulty producing normal red blood cells. The cells may become larger than usual and may not function normally. This can result in a type of anemia known as macrocytic anemia.

Importantly, a person can have vitamin B12 deficiency without having anemia or an increased red blood cell size, particularly during the early stages. Therefore, symptoms and risk factors should also be considered when deciding whether testing is needed.

What Causes Vitamin B12 Deficiency?

Vitamin B12 deficiency can occur when a person does not consume enough B12 or when the body cannot absorb it properly.

Common causes include:

Low dietary intake: This can occur in people following a strict vegetarian or vegan diet who do not consume enough B12-fortified foods or supplements.

• Problems with absorption: Certain stomach or intestinal conditions can prevent the body from absorbing enough vitamin B12
• Autoimmune conditions: Some people develop an autoimmune condition that affects the stomach and reduces the body’s ability to absorb vitamin B12
• Stomach or intestinal surgery: Certain surgical procedures can affect the absorption of vitamin B12
• Certain medications: Long-term use of some medicines, including metformin and proton-pump inhibitors, may increase the risk of vitamin B12 deficiency
• Older age: The ability to absorb vitamin B12 may decrease with age.
• Gastrointestinal diseases: Conditions such as Crohn’s disease can affect the absorption of vitamin B12
• Nitrous oxide exposure: Repeated or significant exposure to nitrous oxide can interfere with the body’s use of vitamin B12

What Are the Symptoms of Vitamin B12 Deficiency?

Vitamin B12 deficiency can affect different parts of the body. Symptoms vary from person to person and may develop slowly.

Common symptoms include:

• Persistent tiredness or fatigue
• Lack of energy
• General weakness
• Pale skin
• Dizziness or lightheadedness
• Shortness of breath, particularly with physical activity
• Headaches
• Difficulty concentrating
• A fast heartbeat or feeling of palpitations

Nerve and Brain-Related Symptoms

Because vitamin B12 is important for healthy nerve function, deficiency may also cause:

• Numbness or tingling, particularly in the hands and feet
• Problems with balance or walking
• Difficulty concentrating or remembering
• Changes in mood
• Confusion in more severe cases

These symptoms can sometimes occur even when a person does not have anemia. For this reason, persistent neurological symptoms should not be ignored.

Mouth and Tongue Changes

Some people with vitamin B12 deficiency may develop:

• A sore or swollen tongue
• A smooth, red tongue, known as glossitis
• Mouth ulcers

Who Is More Likely to Develop Vitamin B12 Deficiency?

Some people have a higher risk of developing vitamin B12 deficiency, including:

• People following a strict vegetarian or vegan diet without adequate B12 supplementation or fortified foods
• Older adults
• People who have had certain stomach or intestinal surgeries
• People with conditions affecting the stomach or intestines
• People with Crohn’s disease or other conditions that affect nutrient absorption
• People with certain autoimmune conditions
• People taking medications such as metformin or long-term acid-reducing medications
• People with significant or repeated exposure to nitrous oxide

How Is Vitamin B12 Deficiency Diagnosed?

Diagnosis usually starts with a discussion of symptoms, diet, medications, medical history, and other possible risk factors.

Laboratory tests can then help determine whether vitamin B12 deficiency is present.

Complete Blood Count (CBC)

A CBC measures different types of blood cells and may show:

• Low hemoglobin, indicating anemia
• Larger-than-normal red blood cells, measured as an increased MCV

However, normal CBC does not always rule out vitamin B12 deficiency.

Vitamin B12 Blood Test

A blood test can measure the amount of vitamin B12 in the blood. When the result is unclear, but vitamin B12 deficiency is still suspected, additional tests may be recommended.

Methylmalonic Acid (MMA)

MMA is a blood test that can provide additional information about vitamin B12 status, particularly when the vitamin B12 result is borderline or unclear.

 

Homocysteine

Homocysteine may also increase when vitamin B12 levels are low. However, it can be affected by other conditions, including folate deficiency, so it should be interpreted together with other test results.

Peripheral Blood Smear

A blood smear allows laboratory professionals to examine blood cells under a microscope. In some cases of B12 deficiency, it may show characteristic changes in the size and appearance of red blood cells and white blood cells.

Identifying the Cause

If vitamin B12 deficiency is confirmed, additional testing may be needed to determine why the deficiency has occurred.

For example, when an autoimmune cause is suspected, an intrinsic factor antibody test may be requested.

Why Is Early Detection Important?

Vitamin B12 deficiency can develop slowly, and symptoms may initially be easy to overlook.

Early testing can help identify the deficiency and determine its possible cause. This allows appropriate treatment to begin and may help prevent complications.

This is particularly important when symptoms such as numbness, tingling, balance problems, or changes in concentration or memory are present, because prolonged vitamin B12 deficiency can cause nerve-related problems.

Take the Next Step with MedLabs

If you are experiencing persistent fatigue, weakness, numbness, tingling, or other symptoms that may be related to vitamin B12 deficiency, laboratory testing can help determine whether your vitamin B12 level is within the expected range.

MedLabs offers vitamin B12 and anemia-related laboratory testing to support your healthcare professional in evaluating your symptoms and determining the appropriate next steps.

Remember, laboratory results should always be interpreted together with your symptoms, medical history, and other relevant investigations by a qualified healthcare professional.

This article is intended for general educational purposes and is not a substitute for professional medical advice, diagnosis, or treatment.