Table 2.
Performance of CDC methods with international reference materials during the 2008–2017 study period1
| Analyte (Unit) | CDC Method | Reference Material | Target Value | Mean ± SD Difference to Target (%), [n] | Performance Score2 |
|---|---|---|---|---|---|
| VIA μg/dL) | HPLC-UV | NIST SRM 968c Level 1 | 84.1 | 2.4 ± 6.3, [45] | Optimal |
| NIST SRM 968c Level 2 | 48.4 | 2.1 ± 4.4, [44] | Optimal | ||
| NIST SRM 968e Level 1 | 34.1 | 0.6 ± 7.0, [198] | Optimal | ||
| NIST SRM 968e Level 2 | 48.2 | 1.3 ± 6.4, [199] | Optimal | ||
| NIST SRM 968e Level 3 | 64.7 | −1.5 ± 6.4, [198] | Optimal | ||
| VID (nmol/L) | HPLC-MS/MS3 | NIST SRM 972 Level 1 | 61.1 | 0.9 ± 7.1, [158] | Optimal |
| NIST SRM 972 Level 2 | 34.9 | 0.5 ± 7.3, [156] | Optimal | ||
| NIST SRM 972 Level 3 | 110 | 0.9 ± 5.5, [155] | Optimal | ||
| NIST SRM 972 Level 4 | 88.1 | −1.6 ± 5.6, [150] | Optimal | ||
| NIST SRM 972a Level 1 | 73.1 | 0.7 ± 5.6, [303] | Optimal | ||
| NIST SRM 972a Level 2 | 47.1 | 0.4 ± 5.7, [307] | Optimal | ||
| NIST SRM 972a Level 3 | 81.8 | 1.6 ± 6.2, [313] | Optimal | ||
| NIST SRM 972a Level 4 | 74.7 | −1.8 ± 5.7, [325] | Optimal | ||
| FOL (nmol/L) | MBA4 | NIST SRM 1955 Level 1 | 4.7 | 6.6 ± 11.6, [96] | Optimal |
| NIST SRM 1955 Level 2 | 10.7 | 4.7 ± 10.1, [98] | Optimal | ||
| NIST SRM 1955 Level 3 | 37.4 | 3.1 ± 8.9, [96] | Optimal | ||
| NIBSC 03/178 | 10.5 | 6.1 ± 10.9, [95] | Optimal | ||
| B12 (pg/mL) | Roche immunoassay5 | NIBSC 03/178 | 480 | 7.2 ± 4.8, [35] | Desirable |
| FER (ng/mL) | Roche immunoassay6 | NIBSC 94/572 1:10 | 630 | 3.6 ± 5.5, [39] | Optimum |
| NIBSC 94/572 1:20 | 315 | 1.6 ± 4.3, [29] | Optimum | ||
| NIBSC 94/572 1:40 | 157.5 | −0.8 ± 4.3, [29] | Optimum | ||
| NIBSC 94/572 1:100 | 63 | −0.7 ± 9.4, [36] | Optimum | ||
| CRP (mg/L) | Roche immunoassay7 | ERM-DA470 | 39.2 | −14 ± 0.1, [5] | Desirable |
| ERM-DA472 | 41.8 | −13 ± 0.0, [14] | Desirable | ||
| ERM-DA-474 | 41.2 | −10 ± 0.0, [8] | Optimum | ||
| NIBSC 85/506 | 100 | −7.2 ± 0.0, [6] | Optimum | ||
| TFR (mg/L) | Roche immunoassay8 | NIBSC 07/202 neat | 60.59 | 1.7 ± 5.2, [22] | n/a |
| NIBSC 07/202 1:2 | 30.3 | 0.84 ± 4.7, [22] | n/a | ||
| NIBSC 07/202 1:4 | 15.1 | 7.2 ± 6.1, [22] | n/a | ||
| NIBSC 07/202 1:8 | 7.56 | 9.2 ± 8.0, [22] | n/a | ||
| NIBSC 07/202 1:16 | 3.78 | 6.5 ± 9.6, [22] | n/a |
B12, serum vitamin B12; CRP, serum C-reactive protein; ERM, European Reference Materials; FER, serum ferritin; FOL, serum folate; MBA, microbiologic assay; NIBSC, National Institute for Biological Standards and Control; VIA, serum vitamin A; VID, serum 25-hydroxyvitamin D.
CDC mean difference is scored based on biologic variation criteria presented in Table 1.
CDC HPLC-MS/MS total VID was the sum of 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 from 2010 to 2017 (method separates 25-hydroxyvitamin D3 from epimer of 25-hydroxyvitamin D3). NIST target values shown do not include epimer of 25-hydroxyvitamin D3.
Target values shown are NIST values for total folate minus the amount of MeFox, an oxidation product of 5-methyltetrahydrofolate to which the MBA does not respond.
Roche Elecsys Vitamin B12 electrochemiluminescence immunoassay “ECLIA” was performed on E-170 platform from July 2009 to June 2016 and on e601 platform from July 2016 to the end of 2017.
Roche Tina-quant Ferritin immunoturbidimetric assay performed on Hitachi 912 platform from 2008 to mid-2009; Roche Elecsys Ferritin electrochemiluminescence immunoassay performed on E-170 platform from mid-2009 to mid-2016 and on e601 platform from mid-2016 to end-2017.
Roche Tina-quant CRPLX immunoturbidimetric assay performed on Hitachi 912 platform during 2008 to mid-2009; Roche Tina-quant CRPL3 immunoturbidimetric assay performed on Mod P platform from mid-2009 to mid-2016 and on c501 platform from mid-2016 to end-2017.
Roche Tina-quant Soluble Transferrin Receptor immunoturbidimetric assay performed on Hitachi 912 platform during 2008, on Mod P platform from mid-2009 to mid-2016, and on c501 platform from mid-2016 to end-2017.
WHO assigned a value of 21.74 mg/L to the Reference Reagent based on a theoretical extinction coefficient and the molecular weight (3); CDC characterized the Reference Reagent during 2008 over multiple days and dilutions and obtained a mean ± SD value of 60.5 ± 0.5 mg/L using the Roche Hitachi 912 clinical analyzer; this value has been used to monitor for potential shifts in the TFR assay over time.