Symptoms of B12 deficiency and its treatment, please。
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"Vitamin B 12 Deficiency"[MeSH Terms] AND treatment
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NIH Office Dietary Supplements vitamin B12 deficiency symptoms treatment fact sheet
Quick answer
Vitamin B12 deficiency can affect the blood, nerves, and sometimes the mouth and digestive system.
Common symptoms
- Tiredness, weakness, reduced exercise tolerance
- Pale skin, shortness of breath, palpitations, dizziness, headaches
- Sore, red or smooth tongue, mouth ulcers
- Reduced appetite, weight loss, diarrhea or constipation
- Tingling, numbness, burning, or “pins and needles” in the hands or feet
- Poor balance, unsteady walking, muscle weakness
- Memory problems, poor concentration, confusion, low mood, irritability
- Blurred vision is uncommon but can occur with severe nerve involvement
Neurologic symptoms can happen even without anemia. Long-standing deficiency may leave permanent nerve damage, so do not ignore numbness, gait problems, or cognitive change.
Common causes
- Low intake, especially strict vegan diets without reliable B12-fortified foods or supplements
- Pernicious anemia, an autoimmune cause that prevents absorption
- Stomach or intestinal disease/surgery, such as coeliac disease, Crohn disease, bariatric surgery, or removal of part of the stomach/ileum
- Medicines that can contribute over time, including metformin and acid-suppressing drugs such as proton-pump inhibitors
- Older age and reduced food absorption
Diagnosis
A clinician usually checks:
- Full blood count, including mean corpuscular volume (MCV)
- Serum B12
- Sometimes methylmalonic acid and homocysteine if the result is borderline
- Folate, iron studies, and testing for causes such as pernicious anemia when appropriate
Treatment
Treatment depends on severity and cause:
-
Mild dietary deficiency with normal absorption
- Oral B12 supplements are often effective.
- Add B12-containing or B12-fortified foods: meat, fish, eggs, dairy, fortified plant milks, breakfast cereals, or nutritional yeast.
- People eating fully vegan diets generally need a regular B12 supplement long term.
-
Severe deficiency, anemia, neurologic symptoms, or suspected malabsorption
- B12 injections, usually intramuscular hydroxocobalamin or cyanocobalamin, are commonly used first.
- Initial doses are given frequently to replenish stores, then maintenance treatment may be needed every few months or monthly depending on the formulation and local protocol.
- Lifelong replacement is often necessary for pernicious anemia or irreversible malabsorption.
-
Treat the cause
- Review medicines, dietary intake, bowel disease, and prior gastrointestinal surgery.
- If folate is also low, clinicians avoid giving folate alone before B12 deficiency is addressed, because anemia can improve while nerve damage continues.
Blood counts often start improving within about a week, but nerve recovery can take months and may be incomplete if treatment is delayed. Recent reviews also support oral B12 as an effective option in many appropriately selected patients, while injections remain particularly appropriate with marked deficiency, neurologic involvement, or poor absorption.
Seek prompt medical assessment if you have new numbness, weakness, trouble walking, confusion, marked breathlessness, chest pain, or severe fatigue.
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https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessio…
Vitamin B12 deficiency can develop slowly, often over years. It can cause anemia and nerve damage, and nerve symptoms may occur even without anemia.
Common symptoms
- Tiredness, weakness, breathlessness, dizziness
- Pale skin, palpitations
- Sore, smooth, red tongue or mouth ulcers
- Loss of appetite or weight loss
- Tingling, numbness, burning sensations, or “pins and needles” in hands or feet
- Poor balance, difficulty walking, muscle weakness
- Memory problems, low mood, irritability, confusion, or cognitive changes
- In severe or prolonged cases: potentially lasting spinal cord and peripheral nerve injury
B12 deficiency commonly arises from low dietary intake, but also from impaired absorption, including pernicious anemia, stomach or ileal surgery, Crohn disease, coeliac disease, and sometimes long-term metformin or acid-suppressing medicines. - Goldman-Cecil Medicine, p. 1064-1090. The deficiency affects blood formation and the nervous system. - Goodman & Gilman’s The Pharmacological Basis of Therapeutics, p. 933.
Diagnosis
A clinician will usually check:
- Full blood count, including red-cell size
- Serum B12
- Sometimes methylmalonic acid and/or homocysteine if results are borderline
- The cause, such as testing for pernicious anemia or reviewing diet and medicines
Do not self-treat suspected deficiency with folic acid alone. Folic acid can improve the anemia while B12-related nerve damage continues.
Treatment
Treatment should replace B12 and correct the underlying cause.
| Situation | Usual approach |
|---|---|
| Dietary deficiency, no severe symptoms | High-dose oral B12 is often used, commonly cyanocobalamin 1,000-2,000 micrograms daily, under clinician guidance. |
| Severe anemia, neurological symptoms, or suspected absorption problem | B12 injections, usually intramuscular hydroxocobalamin or cyanocobalamin, are commonly preferred initially. |
| Pernicious anemia, major ileal disease/resection, or permanent malabsorption | Long-term, often lifelong, replacement is usually needed, frequently by injections or a clinician-selected high-dose oral regimen. |
Evidence suggests high-dose oral B12 can normalize blood B12 comparably to injections in many patients, but injections are generally favored when deficiency is severe, neurologic symptoms are present, or absorption is unreliable. A recent systematic review and network meta-analysis supports effectiveness across routes, while the best route should be individualized.
Get urgent medical assessment now if you have
- New trouble walking, marked balance problems, progressive numbness or weakness
- Confusion or major memory/personality change
- Chest pain, fainting, severe shortness of breath, or rapidly worsening fatigue
Neurologic recovery can be incomplete if treatment is delayed, so tingling, gait, or cognitive symptoms deserve prompt assessment. The NIH B12 fact sheet also notes that neurological changes can occur without anemia.
How do oral B12 tablets compare with injections?
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