OVERVIEW
What is Vitamin D?
Vitamin D is produced in body when body gets exposed to sun’s UV rays or through sources like fish, eggs & fortified dairy products. It is also available as a dietary supplement. It is known to be essential for formation of teeth and bones, & proper growth. Vitamin D undergoes numerous processes inside the body before it can be used by the body. The first transformation that occurs in liver converts it into chemical called 25-hydroxyvitamin D, which is major form present in blood.
What is 25-hydroxyvitamin D lab test?
As 25-hydroxyvitamin D has got long half-life & higher concentration in blood, therefore, it is best way to measure/assess & monitor vitamin D levels in individuals. This laboratory test measures 25-hydroxyvitamin D levels which is a good sign & it determines whether vitamin D levels are too low or too high. This test is also known as 25-OH vitamin D test or calcidiol 25-hydroxycholecalciferol test.
Why is 25-hydroxyvitamin D lab test done?
It is done:
- As it indicates bone weakness (osteoporosis) & bone malformation (rickets).
- To determine abnormal metabolism of calcium which occurs because of excess or deficiency of vitamin D
- To figure out risks of vitamin D deficiency in people OR to diagnose hypervitaminosis D
- To monitor treatment given for vitamin D deficiency
- In diagnosis or monitoring of parathyroid gland problems
- To monitor diseases like cystic fibrosis & Crohn disease, which interfere with fat absorption (as vitamin D is fat-soluble vitamin)
Q1. How is this test performed?
This test is performed on a blood sample. The blood is obtained from the vein and this is performed by a health care provider in the following way.
- clean the skin
- put an elastic band above the area
- insert a needle into a vein (usually in the arm inside of the elbow or on the back of the hand)
- pull the blood sample into a vial or syringe
- take off the elastic band and remove the needle from the vein
Q2. What are the risks associated with this test?
There is no significant risk associated with this test. A small bruise or mild soreness around the blood test site is common and can last for a few days. Get medical care if the discomfort gets worse or lasts longer.
Q3. Is there any preparation required before the test?
Inform your doctor if you are on specific medications. No other preparation required before this test.
Q4. What is Osteomalacia?
Osteomalacia is softening of bone due to demineralization and depletion of calcium from the bones. Osteomalacia is a main characteristic feature of Vitamin D deficiency.
Q5. What is Osteoporosis?
Osteoporosis is a condition of fragile bones with increased susceptibility to fracture. Osteoporosis is a main characteristic feature of vitamin D deficiency and calcium deficiency.
INTERPRETATION OF THE RESULTS:
Ranges indicate:
- Less than 30 nmol/L (12 ng/mL): Deficiency
- 30 nmol/L (12 ng/mL) to 125 nmol/L (50 ng/mL): Potential deficiency
- 50 nmol/L (20 ng/mL) to 125 nmol/L (50 ng/mL): Normal levels
- Higher than 125 nmol/L (50 ng/mL): Higher level or toxicity possible
25-hydroxyvitamin D levels can be low because:
- Not enough sunlight exposure
- Not enough dietary vitamin D to meet body’s demand
- Problem with absorption from intestines
- Drugs like phenytoin interferes with 25-hydroxyvitamin D production in liver
25-hydroxyvitamin D levels can be high because:
- Reflects excess supplementation from vitamin pills or nutritional supplements.
You get tested to determine whether you have vitamin D deficiency, & to determine effect of vitamin D supplementation i.e. if it is adequate or not.
