25-hydroxy vitamin D test

A blood sample is needed.

Usually, you will not need to fast. But this depends on the laboratory and the testing method used. Follow any instructions for not eating before the test.

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.

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. However, testing may be done on people who are at high risk for vitamin D deficiency, such as those who: Are over the age of 65…

The normal range of 25-hydroxy vitamin D is measured as nanograms per milliliter (ng/mL) or nanomoles/liter (nmol/L). Many experts recommend a level from 20 and 40 ng/mL or 60 and 100 nmol/L. Others recommend a level from 30 to 50 ng/mL (75 to 125 nmol/L). The examples above are common measurements for results of…

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 Lack of enough vitamin D in the diet Liver and kidney diseases Poor food absorption Use of certain medicines, including phenytoin,…

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: Excessive…

Bouillon R, Verlinden L, Carmeliet G. Vitamin D: from photosynthesis, metabolism, and action to clinical applications. In: Robertson RP, ed. DeGroot's Endocrinology . 8th ed. Philadelphia, PA: Elsevier; 2023:chap 50. Markell M, Siddiqi HA. Vitamins and trace elements. In: McPherson RA, Pincus MR. Henry's Clinical…