Background Determining serum 25-hydroxyvitamin D [25 (OH) D], 24, 25-dihydroxyvitamin D
[24, 25 (OH) 2D] and the vitamin D metabolite ratio (VMR) allows the identification of …

An intralaboratory study assessing assay variability and bias for determination of serum total
25-hydroxyvitamin D [25 (OH) D] was conducted by the Vitamin D Standardization Program …

The measurement of vitamin D metabolites aids in assessing vitamin D status and in
diagnosing disorders of calcium homeostasis. Most laboratories measure total 25 …

Background Despite an increasing interest in vitamin D status, a reference range of the
nutrient has not been fully established. This is partly due to a paucity of standardized …

Clinical and preclinical studies have provided conflicting data on the postulated beneficial
effects of vitamin D in patients with prostate cancer. In this opinion piece, we discuss …

An interlaboratory comparison study was conducted by the Vitamin D Standardization
Program (VDSP) to assess the performance of liquid chromatography–tandem mass …

The majority of circulating 25-hydroxyvitamin D (25 (OH) D) is protein bound and perhaps
less available than the free fraction of 25 (OH) D; therefore, researchers have proposed that …

An interlaboratory study was conducted through the Vitamin D Standardization Program
(VDSP) to assess commutability of Standard Reference Materials®(SRMs) and proficiency …

This chapter is divided into two sections. An essential point in both is that serum total 25-
hydroxyvitamin D (25 (OH) D) is the clinically accepted biomarker for vitamin D status …

Ninety archived human serum samples from the Vitamin D External Quality Assessment
Scheme (DEQAS) were analyzed using a reference measurement procedure (RMP) based …