From the Guidelines
Vitamin B12 deficiency is a significant health concern that can lead to various neurological and hematological symptoms. The deficiency can cause sub-acute combined degeneration of the spinal cord and polyneuropathies 1, resulting in extensive demyelination in the central nervous system (CNS) and peripheral nervous system (PNS). Clinically, vitamin B12 deficiency is associated with an extensive range of neuromuscular symptoms, including paraesthesia, numbness, muscle weakness, abnormal reflexes, and gait ataxia 1.
Key Symptoms and Signs
- Neuromuscular symptoms: paraesthesia, numbness, muscle weakness, abnormal reflexes, and gait ataxia 1
- Cognitive difficulties: difficulty concentrating, short-term memory loss, and "brain fog" 1
- Eyesight problems: blurred vision, optic nerve dysfunction 1
Treatment and Prevention
Vitamin B12 deficiency can be treated with oral supplements or intramuscular injections of cyanocobalamin or methylcobalamin 1. The recommended dose and frequency of treatment vary depending on the severity of the deficiency and the presence of neurological involvement. For example, patients with neurological involvement may require hydroxocobalamin 1 mg intramuscularly on alternate days until there is no further improvement, followed by maintenance injections every 2 months 1.
Importance of Early Detection and Treatment
Early detection and treatment of vitamin B12 deficiency are crucial to prevent long-term neurological damage and other complications. Metabolic B12 deficiency is frequently missed, as a serum B12 in the normal range is often accepted as ruling out B12 deficiency 1. Therefore, it is essential to measure serum B12 and homocysteine levels in patients with suspected vitamin B12 deficiency and to treat promptly if abnormal 1.
From the FDA Drug Label
Cyanocobalamin is indicated for vitamin B12 deficiencies due to malabsorption which may be associated with the following conditions: Addisonian (pernicious) anemia Gastrointestinal pathology, dysfunction, or surgery, including gluten enteropathy or sprue, small bowel bacteria overgrowth, total or partial gastrectomy Fish tapeworm infestation Malignancy of pancreas or bowel Folic acid deficiency The significance of Vitamin B12 (Cobalamin) deficiency is that it can lead to various conditions, including:
- Addisonian (pernicious) anemia
- Gastrointestinal pathology, dysfunction, or surgery
- Malabsorption due to certain conditions
- Malignancy of pancreas or bowel
- Folic acid deficiency It can also be associated with increased requirements due to conditions such as pregnancy, thyrotoxicosis, hemolytic anemia, hemorrhage, malignancy, hepatic and renal disease 2
From the Research
Significance of Vitamin B12 Deficiency
- Vitamin B12 (Cobalamin) plays a crucial role in cellular metabolism, especially in DNA synthesis, methylation, and mitochondrial metabolism 3, 4.
- Vitamin B12 deficiency can lead to hematological and neurological disorders, and its manifestation can be relatively late, making early diagnosis difficult 4.
- The deficiency can affect individuals at all ages, but it is more common in elderly individuals, infants, children, adolescents, and women of reproductive age, particularly in populations with restricted dietary intake of B12-containing animal-derived foods 3.
Causes and Risk Factors
- Vitamin B12 deficiency can be caused by inadequate intake, inadequate bioavailability, or malabsorption 3, 5.
- Disruption of B12 transport in the blood, or impaired cellular uptake or metabolism, can also lead to an intracellular deficiency 3.
- Certain groups, such as those with gastric or small intestine resections, inflammatory bowel disease, and users of metformin or proton pump inhibitors, are at higher risk of developing vitamin B12 deficiency 6.
Diagnosis and Treatment
- Diagnostic biomarkers for B12 status include decreased levels of circulating total B12 and transcobalamin-bound B12, and abnormally increased levels of homocysteine and methylmalonic acid 3, 7.
- Management of vitamin B12 deficiency depends on B12 supplementation, either via high-dose oral routes or parenteral administration 3, 5, 6, 7.
- Oral administration of high-dose vitamin B12 (1 to 2 mg daily) is as effective as intramuscular administration for correcting anemia and neurologic symptoms, but intramuscular therapy may lead to more rapid improvement 5, 6.