Vitamin D status of county hospital patients assessed by the DiaSorin LIAISON® 25-hydroxyvitamin D assay

Background: Vitamin D is an essential nutrient, and there is a growing appreciation of its clinical significance. In addition, there has recently been a discussion as to the best method of measuring this analyte in serum: immunoassay, HPLC or LC-MS/MS. Due to the increased interest in vitamin D, there has been an exponential increase in the number of clinicians testing their patients and therefore also in the volume of this test run in clinical laboratories. Methods: Vitamin D levels were determined by chemiluminescence immunoassay in a reference laboratory and a subset by LC-MS/MS at San Francisco General Hospital. Results: We developed a robust and rapid LC-MS/MS assay to detect 25-hydroxyvitamin D3 and 02 in serum for use in the routine clinical laboratory. Additionally, we determined that 71% of patients served by San Francisco General Hospital have insufficient serum vitamin D levels (<= 29 ng/ml) and that these levels are significantly associated with parathyroid hormone levels, total calcium concentration, age and ethnicity. Conclusions: The high degree of vitamin D insufficiency at San Francisco General Hospital may be reflective of the status of the patients served by this county hospital: largely an underserved, multi-ethnic urban population. (C) 2010 Elsevier B.V. All rights reserved.