The 25-hydroxy vitamin D ( 25(OH)D ) test is the most accurate way to measure how much vitamin D is in your body. In the kidney, 25-hydroxy vitamin D changes into an active form of the vitamin. The active form of vitamin D helps control calcium and phosphate levels in the body.
Other names include 25-hydroxyvitamin D, 25-OH vitamin D test, and Calcidiol 25-hydroxycholecalciferol test.
Based on research by GrassrootsHealth, it appears as though most adults need about 8,000 IU’s of vitamin D a day in order to raise their serum levels above 40 ng/ml. For children, many experts agree they need about 35 IU’s of vitamin D per pound of body weight.
At the time GrassrootsHealth performed the studies that resulted in this dosage recommendation, the optimal serum level was believed to be between 40 to 60 ng/ml. Since then, the optimal vitamin D level has been raised to 50-70 ng/ml, and when treating cancer or heart disease, as high as 70-100 ng/ml.
What this means is that even if you do not regularly monitor your vitamin D levels (which you should), your risk of overdosing is going to be fairly slim even if you take as much as 8,000 IU’s a day. However, the only way to determine your optimal dose is to get your blood tested regularly, and adjust your dosage to maintain the desired level.
Vitamin D Testing can help with the following
Muscle Cramps / Twitching
The best way to check if your muscle aches are due to vitamin D deficiency is to get tested with a 25 (OH) Vitamin D level. If it is less than 30mg/dl then you should take a vitamin D supplement. Food sources only provide upwards of 100 IU/day.
Key
| Likely to help |
| Highly recommended |
Glossary
Vitamin D
A fat-soluble vitamin essential to one's health. Regulates the amount of calcium and phosphorus in the blood by improving their absorption and utilization. Necessary for normal growth and formation of bones and teeth. For Vitamin D only, 1mcg translates to 40 IU.
Calcium
The body's most abundant mineral. Its primary function is to help build and maintain bones and teeth. Calcium is also important to heart health, nerves, muscles and skin. Calcium helps control blood acid-alkaline balance, plays a role in cell division, muscle growth and iron utilization, activates certain enzymes, and helps transport nutrients through cell membranes. Calcium also forms a cellular cement called ground substance that helps hold cells and tissues together.
Serum
The cell-free fluid of the bloodstream. It appears in a test tube after the blood clots and is often used in expressions relating to the levels of certain compounds in the blood stream.
ng
Nanogram: 0.000000001 or a billionth of a gram.
Pound
454 grams, or about half a kilogram.
Cancer
Refers to the various types of malignant neoplasms that contain cells growing out of control and invading adjacent tissues, which may metastasize to distant tissues.