维生素B12水平

定义

The 维生素B12 level is a blood test that measures how much 维生素B12 在你的血液里.

选择的名字

Cobalamin test; 恶性贫血 - 维生素B12 level

如何执行测试

A 血液样本 是必要的.

How to Prepare for the Test

You should not eat or drink for about 6 to 8 hours before the test.

Certain medicines may affect the results of this test. Your health care provider will tell you if you need to stop taking any medicines. Do not stop any medicine before talking to your provider.

Medicines that can affect the test result include:

• 秋水仙碱
• 新霉素
• Para-aminosalicylic酸
• 苯妥英

考试的感觉如何

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. 这很快就会消失.

为什么要进行测试

This test is most often done when other blood tests suggest a condition called megaloblastic anemia. 恶性贫血 is a form of megaloblastic anemia caused by poor 维生素B12 absorption. This can occur when the stomach makes less of the substance the body needs to properly absorb 维生素B12.

Your provider may also recommend a 维生素B12 test if you have certain nervous system symptoms. A low level of B12 can cause numbness or tingling in the arms 和 legs, 弱点, 失去平衡.

Other conditions for which the test may be done include:

• 突然严重混乱(精神错乱)
• 脑功能丧失(痴呆)
• Dementia due to metabolic causes
• Nerve abnormalities, such as peripheral neuropathy

正常的结果

Normal values are 160 to 950 picograms per milliliter (pg/mL), or 118 to 701 picomoles per liter (pmol/L).

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or may test different samples. Talk to your provider about what your specific test results mean.

异常结果意味着什么

Values of less than 160 pg/mL (118 pmol/L) are a possible sign of a 维生素B12 deficiency. People with this deficiency are likely to have or develop symptoms.

Older adults with a 维生素B12 level less than 100 pg/mL (74 pmol/L) may also have symptoms. Deficiency should be confirmed by checking the level of a substance in the blood called methylmalonic acid. A high level indicates a true B12 deficiency.

Causes of 维生素B12 deficiency include:

• Not enough 维生素B12 in diet (rare, except with a strict vegetarian diet)
• 导致 吸收不良 (例如, 乳糜泻 和 克罗恩病)
• 缺乏 内在因素, a protein that helps the intestine absorb 维生素B12
• Above normal heat production (例如, with 甲状腺机能亢进)
• 怀孕

An increased 维生素B12 level is uncommon. Usually, excess 维生素B12 is removed in the urine.

十大赌博靠谱网络平台 that can increase B12 level include:

• 肝脏疾病(如 肝硬化 or 肝炎)
• Myeloproliferative disorders (例如, polycythemia vera 和 chronic 粒细胞性白血病)

风险

There is little risk involved with having your blood taken. Veins 和 arteries vary in size from one person to another 和 from one side of the body to the other. Taking blood from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight, but may include:

• 大出血
• Fainting or feeling lightheaded
• Multiple punctures to locate veins
• Hematoma (blood buildup under the skin)
• Infection (a slight risk any time the skin is broken)

参考文献

Marcogliese AN, Yee DL. Resources for the hematologist: interpretive comments 和 selected reference values for neonatal, 儿科, 成年人群. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles 和 Practice. 7日艾德. Philadelphia, PA: Elsevier; 2018:chap 162.

梅森JB，布斯SL. Vitamins, trace minerals, 和 other micronutrients. In: Goldman L, Schafer AI, eds. Goldman-Cecil医学. 26日艾德. Philadelphia, PA: Elsevier; 2020:chap 205.

稳定SP. 巨成红细胞性贫血. In: Goldman L, Schafer AI, eds. Goldman-Cecil医学. 26日艾德. Philadelphia, PA: Elsevier; 2020:chap 155.