Abstract
The accuracy of 25-hydroxyvitamin D3 (25OHD3) measurement on specimens collected into serum separator tubes (SSTs) has been questioned because of possible interference by the gel. Possible interference was investigated in SSTs from Becton Dickinson (BD).
Blood specimens were collected simultaneously from 50 normal subjects into plain tubes and SSTs. 25OHD3 was assayed on serum using high performance liquid chromatography (Chromsystems), and Architect (Abbott) and Liaison (Diasorin) immunoassays.
There were no significant differences between 25OHD3 results (means ± SE, nmol/l) obtained from specimens collected into plain tubes and SSTs assayed by HPLC (39.0 ± 2.7 vs. 39.3 ± 2.7), Liaison (32.9 ± 2.2 vs. 32.8 ± 2.3), or Architect (43.1 ± 2.8 vs. 43.2 ± 2.8). In specimens collected into plain tubes and SSTs, 25OHD3 measurements by HPLC correlated significantly (P < 0.0001) with those from the Architect (r = 0.895, r = 0.908) and Liaison (r = 0.907, r = 0.913), respectively.
The gel in SSTs (BD) does not interfere with the measurement of 25OHD3 by HPLC or common immunoassays. This important finding may enable clinical laboratories to make cost savings by using SSTs without concerns about inaccuracy.