25-羟基维生素D试验

定义

The 25-羟基维生素D试验 is the most accurate way to measure how much vitamin D is in your body.

Vitamin D helps control calcium and phosphate levels in the body.

选择的名字

25-OH vitamin D test; Calcidiol; 25-hydroxycholecalciferol test

如何执行测试

A 血液样本 是必要的.

如何准备考试

通常，你不需要禁食. But this depends on the laboratory and the testing method used. Follow any instructions for not eating before the test.

考试的感觉如何

When the needle is inserted to draw blood, some people feel moderate pain. 其他人只感到刺痛或刺痛. 之后，可能会有一些悸动.

为什么要进行测试

This test is done to determine if you have too much or too little vitamin D in your blood. Screening of all adults, even when pregnant, for low vitamin D levels is generally not recommended.

然而, screening may be done on people who are at high risk for vitamin D deficiency, 比如:

• Are over the age of 65 (both skin production of vitamin D and gut absorption of vitamin D becomes lower as we get older)
• Are obese (or have lost weight from bariatric surgery)
• Are taking certain medicines, such as phenytoin
• 骨质疏松或骨瘦如柴
• 限制阳光照射
• Have problems absorbing vitamins and nutrients in their intestines, 比如溃疡性结肠炎患者, 克罗恩病, 或者乳糜泻

正常的结果

The normal range of 25-hydroxy vitamin D is measured as nanograms per milliliter (ng/mL). Many experts recommend a level between 20 and 40 ng/mL. Others recommend a level between 30 and 50 ng/mL.

The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some laboratories use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results, and whether you may need vitamin D supplements.

• 25 hydroxy vitamin D3 (cholecalciferol) is the vitamin D that your own body has made or that you absorbed from an animal source (such as fatty fish or liver) or a cholecalciferol supplement.
• 25 hydroxy vitamin D2 (ergocalciferol) is the vitamin D that you have absorbed from foods fortified with plant vitamin D or from an ergocalciferol supplement.
• The two hormones (ergo- and cholecalciferol) work similarly in the body. The important value is the total 25 hydroxy vitamin D level in your blood.

异常结果意味着什么

A lower-than-normal level can be due to a vitamin D deficiency, which can result from:

• Lack of skin exposure to sunlight, darkly pigmented skin, or consistent use of high-SPF sunscreen
• 饮食中缺乏足够的维生素D
• 肝肾疾病
• 食物吸收不良
• Use of certain medicines, including phenytoin, phenobarbital, and rifampin
• Poor vitamin D absorption due to advanced age, 减肥手术, or conditions in which fat is not absorbed well

A low vitamin D level is more common in African American children (especially in the winter), as well as in infants who are breastfed only.

A higher-than-normal level may be due to excess vitamin D, a condition called 维生素D过多症. This is most commonly caused by taking too much vitamin D. It can result in too much calcium in the blood (血钙过多). This leads to many symptoms and kidney damage.

风险

There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and 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
• 多次穿刺定位静脉
• 昏厥或感到头晕
• 血肿(皮肤下积血)
• Infection (a slight risk any time the skin is broken)

参考文献

清汤R. Vitamin D: from photosynthesis, metabolism, and action to clinical applications. In: Jameson JL, De Groot LJ, de Kretser DM, et al, eds. 内分泌学:成人和儿童. 7日艾德. Philadelphia, PA: Elsevier Saunders; 2016:chap 59.

陈国强，张国强. Vitamin D (cholecalciferol) -- plasma or serum. 见:陈国强，张国强编. 实验室测试和诊断程序. 6日艾德. St Louis, MO: Elsevier Saunders; 2013:1182-1183.

US Preventive Services Task Force; Krist AH, Davidson KW, et al. Screening for vitamin D deficiency in adults: US Preventive Services Task Force Recommendation Statement. 《十大赌博靠谱网络平台》. 2021;325(14):1436-1442. PMID: 33847711 pubmed.ncbi.nlm.国家卫生研究院.gov / 33847711 /.