If your results show that routine vitamin D tests are medically necessary, you should have them every 3-6 months. Retesting ensures you receive proper treatment and lowers the chance of vitamin D ...

The Vitamin D Blood Test (25-OH Vitamin D): Who, How, When, and Where Clinically speaking, things began to change in the 1970s when the blood test for vitamin D (known as the "25-OH vitamin D ...