Vitamin D deficiency is increasingly being recognized as a common condition in the United States. Testing for vitamin D nutritional status has increased markedly throughout the last several years. There is, however, confusion over the appropriate test for assessing vitamin D nutritional status.

The main circulating form of vitamin D is 25-hydroxyvitamin D. Measurement of 25-hydroxyvitamin D ("Vitamin D, 25-hydroxy" in Epic) is the appropriate test for routine screening for nutritional status of vitamin D. The most biologically active form of vitamin is 1,25-dihydroxyvitamin D. Measurement of this active form of vitamin D ["Vitamin D (1,25-dihydroxy)" in Epic] may seem logical in assessing nutritional vitamin D deficiency. However, Vitamin D (1,25-dihydroxy) varies day to day in relation to calcium status and other factors. Thus, measurement of Vitamin D (1,25-dihydroxy) is NOT useful in the diagnosis of nutritional vitamin D deficiency, and actually can be misleading with a normal value possible on a patient who actually has overall severe vitamin D deficiency.

Analysis of vitamin D test ordering patterns at UIHC indicate a large number of cases where "Vitamin D (1,25-dihydroxy)" is being ordered inappropriately as the routine screen for vitamin D nutritional status. Options to order "Vitamin D (1,25-dihydroxy)" have also been incorporated into many Epic order sets. We have found order sets where there is only an option to order "Vitamin D (1,25-dihydroxy)", which would foster the impression that this is the choice for screening. Measurement of "Vitamin D (1,25-dihydroxy)" is intended for workup of assessment of hypercalcemia, assessment of vitamin D in patients with renal failure, and certain malignancies. Also, the direct cost of the "Vitamin D (1,25-dihydroxy)" assay for the hospital is approximately double that of the "Vitamin D, 25-hydroxy" assay.

We recommend the following:

1. For screening of vitamin D deficiency, order "Vitamin D, 25-hydroxy" [Epic # LAB535]


2. Look over Epic order sets (including personal ones) and see whether "Vitamin D (1,25-dihydroxy)" [Epic # LAB536] is included instead of "Vitamin D, 25-hydroxy". If it is, please have this corrected.


3. Vitamin D (1,25-dihydroxy)" has narrow indications and is intended for workup of assessment of hypercalcemia, assessment of vitamin D in patients with renal failure, and certain malignancies, and is NOT indicated for routine screening.

Questions can be directed to Matthew Krasowski M.D., Ph.D. (Medical Director, Clinical Chemistry Laboratory) at 384-9380.