The Vitamin D test measures the level of 25-hydroxyvitamin D (25-OH Vitamin D) in the blood, which is the main circulating form of vitamin D and the best indicator of overall vitamin D status in the body. Vitamin D is a fat-soluble vitamin that the body produces when the skin is exposed to sunlight and also obtains from certain foods and supplements.
Vitamin D plays a vital role in calcium and phosphorus absorption, bone health, immune system function, muscle function, and the reduction of inflammation. This test is used to diagnose vitamin D deficiency or insufficiency, which can lead to rickets in children, osteomalacia and osteoporosis in adults, increased susceptibility to infections, and muscle weakness. It is commonly ordered for individuals with limited sun exposure, darker skin tones, obesity, malabsorption conditions, or those on medications affecting vitamin D metabolism. It is also used to monitor vitamin D supplementation therapy.
