Recommendation on an updated standardization of serum magnesium reference ranges.

Purpose: Serum magnesium is the most frequently used laboratory test for evaluating clinical magnesium status. Hypomagnesemia (low magnesium status), which is associated with many chronic diseases, is diagnosed using the serum magnesium reference range. Currently, no international consensus for a magnesemia normal range exists.

The status of serum vitamin D in patients attending a general rheumatology clinic in the UK.

Vitamin D deficiency may be involved in the pathogenesis of several inflammatory conditions. This study aimed to determine the status of vitamin D in the rheumatology patients who were diagnosed with different rheumatic, inflammatory and non-inflammatory diseases. In this cross-sectional observational study, we reviewed the levels of serum vitamin D in patients who attended the general rheumatology clinics for the first time between May 2012 and October 2012.

Biological variation of vitamins in blood of healthy individuals.

Background: Components of biological variation can be used to define objective quality specifications (imprecision, bias, and total error), to assess the usefulness of reference values [index of individuality (II)], and to evaluate significance of changes in serial results from an individual [reference change value (RCV)]. However, biological variation data on vitamins in blood are limited. The aims of the present study were to determine the intra- and interindividual biological variation of vitamins A, E, B(1), B(2), B(6), C, and K and carotenoids in plasma, whole blood, or erythrocytes from apparently healthy persons and to define quality specifications for vitamin measurements based on their biology.