What are the symptoms of Vitamin B12 (Cobalamin) deficiency?

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Last updated: May 29, 2025View editorial policy

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From the Guidelines

Vitamin B12 deficiency can cause a range of symptoms including abnormal findings on a blood count, cognitive difficulties, eyesight problems, blurred vision, and other neurological and psychiatric symptoms. These symptoms are supported by recent evidence from the BMJ 1, which highlights common symptoms and signs of vitamin B12 deficiency. Some of the key symptoms include:

  • Abnormal findings, such as anaemia or macrocytosis, on a blood count
  • Cognitive difficulties, such as difficulty concentrating or short term memory loss
  • Eyesight problems related to optic nerve dysfunction, including blurred vision Additionally, other studies 1 have shown that vitamin B12 deficiency can also cause neuromuscular symptoms, such as paraesthesia, numbness, muscle weakness, and gait ataxia, which can become more severe as deficiency progresses. It is essential to seek medical evaluation if B12 deficiency is suspected, as blood tests can confirm the diagnosis, and early treatment can prevent permanent nerve damage 1.

From the Research

Symptoms of B12 Deficiency

The symptoms of B12 deficiency are not explicitly stated in the provided studies. However, the studies discuss the diagnosis, treatment, and causes of B12 deficiency.

Diagnosis and Treatment

  • The diagnosis of B12 deficiency can be made using serum B12 levels, holotranscobalamin, serum methylmalonic acid, and plasma homocysteine measurements 2.
  • Treatment options for B12 deficiency include intramuscular (IM) injections, oral administration, and sublingual (SL) tablets 3, 4, 5.
  • High oral doses of B12 (1000 mcg and 2000 mcg) were found to be as effective as IM administration in achieving haematological and neurological responses 3.
  • SL administration of B12 was found to be as effective as IM administration in correcting serum B12 levels and hematologic abnormalities in children 4 and adults 5.

Causes of B12 Deficiency

  • B12 deficiency can be caused by inadequate dietary intake, malabsorption, and certain diseases such as digestive diseases and pancreatic insufficiency 6.
  • The main causes of B12 malabsorption include inherited disorders, bariatric surgery, gastrectomies, pancreatic insufficiency, and certain diseases such as celiac disease and inflammatory bowel diseases 6.

References

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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