Normal Range for 25-Hydroxyvitamin D2
May 11, 2022
Source: Cainiu Health
Dr. Pan Yongyuan
Introduction
The normal serum range for 25-hydroxyvitamin D is 10–80 µg/L, equivalent to 10–80 ng/mL. 25-Hydroxyvitamin D is the biologically active form of vitamin D generated in the body. Vitamin D itself has no physiological activity. Studies have employed tritium (³H)-labeled vitamin D₃. Intestinal-absorbed vitamin D₃ undergoes initial C-25 hydroxylation in the liver.
Normal values for 25-hydroxyvitamin D2 in young children vary depending on the specific assay used; therefore, reference ranges differ across laboratories. What is the normal value for 25-hydroxyvitamin D2 according to the reference range provided by your testing laboratory?
Normal Range for 25-Hydroxyvitamin D
The normal serum concentration of 25-hydroxyvitamin D ranges from 10 to 80 µg/L (equivalent to 10–80 ng/mL). 25-Hydroxyvitamin D represents the major circulating, biologically active metabolite of vitamin D in the body. Vitamin D itself has no direct physiological activity. Studies using tritium-labeled (³H) vitamin D₃ have shown that orally absorbed vitamin D₃ undergoes hydroxylation at carbon-25 in the liver, forming 25-hydroxyvitamin D₃. This metabolite is subsequently converted in renal mitochondria into the highly active form, calcitriol (1,25-dihydroxyvitamin D₃), which is then transported to the intestinal mucosa to promote calcium absorption—the hallmark physiological action of vitamin D. Specifically, calcitriol induces synthesis of calbindin (calcium-binding protein) in the small intestine and simultaneously acts on bone tissue to facilitate calcium mobilization and deposition.
25-Hydroxyvitamin D is the predominant circulating form of vitamin D in humans. Its normal reference range depends significantly on the analytical methodology employed by the laboratory; generally, a level above 30 ng/mL is considered normal. A serum 25-hydroxyvitamin D concentration below 30 ng/mL strongly suggests vitamin D deficiency and is widely regarded as the gold standard for diagnosing vitamin D deficiency.
Vitamin D toxicity may be diagnosed in patients with suspected overdose or excessive supplementation. Assessing vitamin D status—whether deficient, insufficient, or replete—helps identify individuals who may benefit from vitamin D supplementation to achieve optimal serum levels. We hope this information is helpful to you!
