During a vitamin d blood test, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
Low vitamin D levels can help diagnose a case of secondary hyperparathyroidism.
Often Vitamin D levels are tested along with serum calcium, phosphorous, parathyroid hormone.
For patients with renal diseases 1,25 dihydroxy vitamin D should be tested.