Vitamin B12 is essential for brain and nerve function. A vitamin B12 deficiency can cause headaches, fatigue, muscle weakness, and depression. Low levels of vitamin B12 can be due to not getting enough vitamin B12 in your diet or the body being unable to absorb the vitamin due to another medical condition.
Diagnosing vitamin B12 deficiency can be tricky because the symptoms are similar to other health conditions.
This article looks at the symptoms, causes, and diagnosis of vitamin B12 deficiency. It also discusses treatment for vitamin B12 deficiency.
Vitamin B12 Deficiency Symptoms
Vitamin B12 plays a complex role in your body. This is why B12 deficiency has so many potential symptoms.
There are four main categories of vitamin B12 complications. A complication is a problem caused by a medical condition or treatment.
These categories can cause a range of symptoms.
Anemia
Vitamin B12 plays a role in the production of red blood cells (RBCs). These cells carry oxygen through the body. Oxygen helps your body produce energy.
Vitamin B12 deficiency leads to defective RBCs. This causes anemia. Anemia can make you feel weak and fatigued.
Neuropathy
Vitamin B12 is also a vital part of a healthy nervous system. Low B12 can cause the nerves in your brain, spinal cord, and elsewhere in your body to slowly degenerate.
This is called neuropathy, an impairment in nerve function. It causes weakness and imbalance. These symptoms can be worse if you also have anemia.
Myelopathy
Myelopathy is an impairment of the spinal cord. It happens when neurons in part of the spinal cord deteriorate. Neurons are the cells that receive and process information from the outside world.
This results in muscle weakness. It can also cause difficulties in sensing light touch and vibration.
People with myelopathy may also have problems with proprioception. This is the ability to judge your body position, such as knowing how high you’re holding up an arm without looking.
People with this condition may also have neuropathy-like symptoms.
Dementia
Vitamin B12 deficiency may cause dementia. These symptoms may include:
Memory lossCognitive decline when the brain has difficulty with things like memory and judgmentBehavioral changesProblems with self-care
Severe and long-term vitamin B12 deficiency can lead to psychosis. People with psychosis have a hard time telling the difference between what is real and what is not real.
Other Symptoms
Other symptoms of vitamin B12 deficiency may include:
Low white blood cell count, which increases your risk of infection Low platelet count, which increases your risk of bleeding Headaches Weight loss Mood changes, especially depression Behavioral changes Walking problems Loss of or diminished sense of smell Swollen tongue
What Causes Vitamin B12 Deficiency?
Vitamin B12 deficiency has two primary causes. Some people do not get enough B12 in their diet. Others have problems absorbing B12 in the intestines.
Inadequate Intake
Vitamin B12 is found in many food sources. These include:
FishMeatMilkFortified cereals
Many sources of vitamin B12 come from animal proteins. Because of this, long-term vegetarians or vegans who don’t take B12 supplements are at risk for vitamin B12 deficiency.
The risk is also higher in the elderly and people who abuse alcohol.
Impaired Absorption
Vitamin B12 is absorbed in the gut with the help of a protein called intrinsic factor. When the process of absorption doesn’t work right, you may develop B12 deficiency.
Causes of impaired B12 absorption include:
Pernicious anemia, an autoimmune disorder in which antibodies attack the cells that release intrinsic factor Inflammatory gastrointestinal (GI) disorders like Crohn’s disease and celiac disease Prolonged use of certain medications like the diabetes medication Glucophage (metformin) and stomach acid-reducing proton pump inhibitors (PPIs) Gastric bypass, a weight loss surgery that changes the structure of the stomach GI resection surgery, a treatment for serious medical problems like bowel obstruction or cancer
Diagnosis of Vitamin B12 Deficiency
The diagnosis of vitamin B12 isn’t always obvious. This is because many of the common symptoms overlap with those of other health conditions.
Your medical team may consider a number of diagnoses besides B12 deficiency.
History and Physical Examination
Your medical history can help your doctor understand your symptoms. A physical exam may also help identify the signs of B12 deficiency.
For example, a weak, rapid pulse or pale fingers may be a sign of anemia. Signs of neuropathy can include low sensation in your feet and poor reflexes. Confusion or trouble communicating are common signs of dementia.
Laboratory Tests
Laboratory tests can confirm your diagnosis. These tests include a complete blood count (CBC) and a vitamin B12 level.
B12 deficiency is associated with a particular type of anemia. This type, called macrocytic anemia, can be identified with a blood smear. With this type of anemia, RBCs are large and may have varied shapes and sizes.
Imaging and Specialized Tests
Other tests can be used to help confirm a diagnosis. These include nerve conduction studies, which measure the speed of the electrical signals in your nerves.
These tests can’t confirm B12 deficiency on their own, though. This is why they are usually used alongside other diagnostic tools.
How Vitamin B12 Deficiency Is Treated
Vitamin B12 deficiency can be managed with supplemental B12. This could be an oral supplement or an injection. If your B12 deficiency is caused by a problem with absorption, you may need an injection. The injection will help the vitamin absorb directly into your body.
Some patients need lifelong B12 supplementation. This usually depends on the cause of the deficiency. You may need to continue taking B12 supplements even after your symptoms improve.
Rehabilitation
You may have long-lasting symptoms even after treatment. Numbness, tingling, and weakness can impair your balance. A physical or occupational therapist can help you develop strategies to cope with these long-term problems.
Memory problems can improve as your vitamin B12 levels are corrected. Still, you may have some deficits in your thinking skills for a long time. Cognitive rehabilitation and therapy can help you improve your thinking and problem-solving skills.
Summary
If you have a vitamin B12 deficiency, you may have symptoms of anemia, problems with your nerves, sensory issues, or even dementia. Many of these symptoms can be confused with other conditions, making vitamin B12 deficiency hard to diagnose.
The two primary causes of B12 deficiency are low B12 levels in the diet and problems absorbing the vitamin.
Vitamin B12 deficiency is diagnosed with a medical history, exam, laboratory tests, and other tests. It is usually treated with supplemental B12.
You may need long-term rehabilitation after treatment in order for your symptoms to improve.
A Word From Verywell
Vitamin B12 deficiency can be a complicated diagnosis. This is because the effects and symptoms are so varied.
You might not have sudden symptoms of B12 deficiency. Instead, you may go through periods of gradual or intermittent declines in your vitamin B12 level. This can cause subtle or off-and-on symptoms.
If you have an inflammatory GI condition or if you have had gastric bypass, you may need preventive treatment. Regular vitamin B12 injections can help you avoid B12 deficiency.
There was an error. Please try again.
