How to Prepare for the Test Fast for 4 hours before the test. The physical and psychological preparation you can provide for this or any test or procedure depends on your child's age, interests, previous experience, and level of trust. How the Test will Feel When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing. This test is used to determine if a patient has kidney disease .
Vitamin D has to be activated by adding hydroxyl groups before it becomes a hormone.
A second hydroxylation takes place in the kidneys. 25-hydroxy vitamin D Please read this Important notice .