25-OH-Vitamin D Assays

Correlation among 25-hydroxy-vitamin D assays.

CONTEXT Measurement of circulating 25-hydroxy-vitamin D [25(OH)D]) is the accepted clinical indicator of vitamin D status. However, between-laboratory differences in measurement of this analyte exist, which may confound clinical care. OBJECTIVES We investigated the current agreement of 25(OH)D measurement in clinical laboratories and explored the possibility that simple calibration would impr...

Effects of vitamin D binding protein phenotypes and vitamin D supplementation on serum total 25(OH)D and directly measured free 25(OH)D

OBJECTIVE To determine the relationship between serum total 25-hydroxyvitamin D (25(OH)D), directly measured free 25(OH)D and calculated free 25(OH)D with regard to vitamin D-binding protein (DBP) phenotypes, sex, BMI, age and season, and their interrelationship to vitamin D supplementation. DESIGN, PATIENTS AND INTERVENTIONS A randomized controlled trial with 20 000 IU of vitamin D3 per week...

Serum 25-OH vitamin D levels in patients with fibromyalgia.

BACKGROUND The association between low levels of 25-hydroxyvitamin D and non-specific musculoskeletal pain, including fibromyalgia syndrome, is controversial. Several studies have reported a "positive association" and two others found "no association." OBJECTIVES To test levels of 25OHD in patients with fibromyalgia syndrome and in matched controls. METHODS The study population comprised 68...

Defining vitamin D deficiency in children: beyond 25-OH vitamin D serum concentrations.

25(OH) vitamin D serum values and rheumatoid arthritis disease activity (DAS28ESR)

Background: The role of vitamin D in the pathogenesis of rheumatoid arthritis is under investigation. This study was designed to evaluate the correlation between serum values of 25(OH) vitamin D [25(OH)D] and disease activity in rheumatoid arthritis (RA) patients according to Disease Activity Score 28 joints and ESR (DAS28ESR). Methods: Ninety-nine patients according to ACR classification crit...