Scheme Information Sheets

UK NEQAS for Vitamin D

Scheme Particulars	Indicative Details
Accreditation body	UKAS
ISO/IEC Accreditation status	ISO/IEC 17043:2023
UKAS Accredited Proficiency Testing Provider No	7860
Objective of Scheme	Provides EQA coverage and analytical assessment using endogenous material for Vitamin D. The Scheme covers the analytical working range but does focus at the clinically important lower concentrations. The Target Value is the Mass Spectrometry method mean, but this is validated annually by analyses of a number of pools by a reference method at CDC in Atlanta
Pre-, Analytical, Post- status	Analytical/Post
Number of distributions per year (nominal)	11
Specimens per distribution	3
Number of Specimens per annum	33
Frequency of distribution	Monthly
Scoring system	ABC
Material distributed	Pooled, liquid human serum with or without exogenous added analyte
Programme Director(s) / Organiser(s)	Rachel Marrington
Criteria for participation	All, but overseas by courier
Nominal sample volume (mL)	0.4
Sample presentation TACs	All analytes in the same tube
Data in Chemistry on-line Dashboard	Yes

Analyte	Approx Range	Default Units	Target Value	B Score Limit (%)	C Score Limit (%)
25-OH Vitamin D2	0 – 250	nmol/L	OGLTM	20.0	25.0
25-OH Vitamin D3	0 – 250	nmol/L	OGLTM	20.0	25.0
Total 25-OH Vitamin D	0 – 250	nmol/L	OGLTM	20.0	25.0
Vit D Interpretation	~	D, I, A or T	~	~	~

Abbreviation	Expansion
ALTM	All Laboratory Trimmed Mean
GLTM	Group Laboratory Trimmed Mean – which is the Method Principle Mean
MLTM	Method Laboratory Trimmed Mean – usually a manufacturer system / analyser mean
XALTM	An external value that may be from a Reference Method System
OGLTM	A Method Principle Mean used as the target for all laboratories
OMLTM	A specific Method Mean used as a target for all laboratories
MED	Median