25-hydroxy vitamin D

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Blood test

25-OH vitamin D

The normal range is 16.0 to 74.0 ng/mL. Normal value ranges may vary slightly among different laboratories.

Note: ng/mL = nanograms per milliliter

Low 25-hydroxy vitamin D levels indicate a deficiency in vitamin D. Vitamin D deficiency can result from lack of exposure to sunlight, lack of adequate vitamin D in the diet, liver and kidney diseases, malabsorption, and medications such as phenytoin, phenobarbital, and rifampin. Vitamin D deficiency may lead to low blood calcium levels (hypocalcemia), thin or weak bones (osteoporosis and osteomalacia), and high levels of parathyroid hormone (secondary hyperparathyroidism).

High 25-hydroxy vitamin D indicates excess vitamin D (hypervitaminosis D) and is usually caused by too much vitamin D in the form of doctor-prescribed dietary supplements. This can lead to high calcium levels (hypercalcemia).

Review Date: 02/27/2006
Reviewed By: David Juan, MD, Specializing in Endocrinology Issues, Good Hand Medical Center and Alperin Medical Clinics, Santa Clara, CA. Review provided by VeriMed Healthcare Network.