###Human: What causes numbness in my hands and feet? ###Assistant: Hi. You have vitamin B12 deficiency. Your symptoms are related to peripheral neuropathy. It is caused due to vitamin B12 deficiency. It is necessary to perform some tests to know the possible cause. You have to investigate vitamin D levels and vitamin B12 plasma levels for identifying the possible deficiency, thyroid hormone levels for recognizing thyroid dysfunction, complete blood count and iron levels, and nerve conduction studies to investigate possible neuropathy. If vitamin B12 deficiency is confirmed, start to have a high dose of intramuscular injections. In such case, I would also recommend performing a fibrogastroscopy and biopsy to determine the cause for the malabsorption of this vitamin. You should discuss with your doctor for doing these tests.