Vitamin B12 deficiency causes no symptoms in most cases. Hence, it is often difficult to diagnose. Diagnosis requires a detailed history, physical examination and proper testing. If vitamin B12 deficiency is not treated, it progresses slowly and unnoticed. In the initial stages of the disease, it may cause symptoms because of megaloblastic anaemia. As the disease progresses, it damages the neuron and causes neurological symptoms. According to some studies, older patients may present with neuropsychiatric disease in the absence of hematologic findings. If the deficiency is not treated, severe B12 deficiency can be fatal. Some cases can prove fatal and may show symptoms of severe myelopathy, encephalopathy, or anaemia.
How long does vitamin B12 deficiency last
Vitamin B12 deficiency responds very well to treatment. Treatment of patients having megaloblastic anaemia, caused by vitamin B12 deficiency, with B12 supplements can completely reverse the process. Haemoglobin synthesis begins to improve within a few days of starting the treatment and brisk reticulocytosis starts within a week of initiating treatment.
Patients with neurological symptoms may not respond so well to treatment. Blood levels of the vitamin may be normalised and MRI improvement may be observed. But complete resolution of symptoms occurs only in some and not all patients who have undergone vitamin B12 replacement. Treatment halts progression of the disease.
Treatment for B12 deficiency is for prolonged duration. Oral vitamin B12 is given with a dose of 1,000 to 2,000 mcg per day for 1-2 weeks. This is followed by life-long supplementation of 1,000 mcg per day. The dose of intramuscular B12 is 100 to 1,000 mcg every day or every other day for 1-2 weeks. This is followed by 100-1,000 mcg every 1-3 months. This may continue lifelong.
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