Abstract
BACKGROUND: C-peptide is a marker of insulin secretion in diabetic patients. We assessed within- and between-laboratory imprecision of C-peptide assays and determined whether serum calibrators with values assigned by mass spectrometry could be used to harmonize C-peptide results. METHODS: We sent 40 different serum samples to 15 laboratories, which used 9 different routine C-peptide assay methods. We also sent matched plasma samples to another laboratory for C-peptide analysis with a reference mass spectrometry method. Each laboratory analyzed 8 of these samples in duplicate on each of 4 days to evaluate within- and between-day imprecision. The same 8 samples were also used to normalize the results for the remaining samples to the mass spectrometry reference method. RESULTS: Within- and between-run CVs ranged from <2% to >10% and from <2% to >18%, respectively. Normalizing the results with serum samples significantly improved the comparability among laboratories and methods. After normalization, the differences among laboratories in mean response were no longer statistically significant (P = 0.24), with least-squares means of 0.93-1.02. CONCLUSIONS: C-peptide results generated by different methods and laboratories do not always agree, especially at higher C-peptide concentrations. Within-laboratory imprecision also varied, with some methods giving much more consistent results than others. These data show that calibrating C-peptide measurement to a reference method can increase comparability between laboratories.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1023-1026 |
| Number of pages | 4 |
| Journal | Clinical Chemistry |
| Volume | 54 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jun 1 2008 |
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ASJC Scopus subject areas
- Clinical Biochemistry
Cite this
Standardization of C-peptide measurements. / Little, Randie R.; Rohlfing, Curt L.; Tennill, Alethea L.; Madsen, Richard W.; Polonsky, Kenneth S.; Myers, Gary L.; Greenbaum, Carla J.; Palmer, Jerry P.; Rogatsky, Eduard; Stein, Daniel T.
In: Clinical Chemistry, Vol. 54, No. 6, 01.06.2008, p. 1023-1026.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Standardization of C-peptide measurements
AU - Little, Randie R.
AU - Rohlfing, Curt L.
AU - Tennill, Alethea L.
AU - Madsen, Richard W.
AU - Polonsky, Kenneth S.
AU - Myers, Gary L.
AU - Greenbaum, Carla J.
AU - Palmer, Jerry P.
AU - Rogatsky, Eduard
AU - Stein, Daniel T.
PY - 2008/6/1
Y1 - 2008/6/1
N2 - BACKGROUND: C-peptide is a marker of insulin secretion in diabetic patients. We assessed within- and between-laboratory imprecision of C-peptide assays and determined whether serum calibrators with values assigned by mass spectrometry could be used to harmonize C-peptide results. METHODS: We sent 40 different serum samples to 15 laboratories, which used 9 different routine C-peptide assay methods. We also sent matched plasma samples to another laboratory for C-peptide analysis with a reference mass spectrometry method. Each laboratory analyzed 8 of these samples in duplicate on each of 4 days to evaluate within- and between-day imprecision. The same 8 samples were also used to normalize the results for the remaining samples to the mass spectrometry reference method. RESULTS: Within- and between-run CVs ranged from <2% to >10% and from <2% to >18%, respectively. Normalizing the results with serum samples significantly improved the comparability among laboratories and methods. After normalization, the differences among laboratories in mean response were no longer statistically significant (P = 0.24), with least-squares means of 0.93-1.02. CONCLUSIONS: C-peptide results generated by different methods and laboratories do not always agree, especially at higher C-peptide concentrations. Within-laboratory imprecision also varied, with some methods giving much more consistent results than others. These data show that calibrating C-peptide measurement to a reference method can increase comparability between laboratories.
AB - BACKGROUND: C-peptide is a marker of insulin secretion in diabetic patients. We assessed within- and between-laboratory imprecision of C-peptide assays and determined whether serum calibrators with values assigned by mass spectrometry could be used to harmonize C-peptide results. METHODS: We sent 40 different serum samples to 15 laboratories, which used 9 different routine C-peptide assay methods. We also sent matched plasma samples to another laboratory for C-peptide analysis with a reference mass spectrometry method. Each laboratory analyzed 8 of these samples in duplicate on each of 4 days to evaluate within- and between-day imprecision. The same 8 samples were also used to normalize the results for the remaining samples to the mass spectrometry reference method. RESULTS: Within- and between-run CVs ranged from <2% to >10% and from <2% to >18%, respectively. Normalizing the results with serum samples significantly improved the comparability among laboratories and methods. After normalization, the differences among laboratories in mean response were no longer statistically significant (P = 0.24), with least-squares means of 0.93-1.02. CONCLUSIONS: C-peptide results generated by different methods and laboratories do not always agree, especially at higher C-peptide concentrations. Within-laboratory imprecision also varied, with some methods giving much more consistent results than others. These data show that calibrating C-peptide measurement to a reference method can increase comparability between laboratories.
UR - http://www.scopus.com/inward/record.url?scp=44849122916&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=44849122916&partnerID=8YFLogxK
U2 - 10.1373/clinchem.2007.101287
DO - 10.1373/clinchem.2007.101287
M3 - Article
C2 - 18420730
AN - SCOPUS:44849122916
VL - 54
SP - 1023
EP - 1026
JO - Clinical Chemistry
JF - Clinical Chemistry
SN - 0009-9147
IS - 6
ER -