TABLE 2.
Methylmalonic acid measurements in NHANES1
| Survey | Measurement procedure | Matrix | Laboratory | Population age |
| 1974–1975 | — | — | — | — |
| 1976–1980 | — | — | — | — |
| 1988–1994 | GC/MS | Surplus serum | Tufts University | 30–39 y, ≥65 y |
| 1999–2000 | GC/MS | Plasma | NCEH | ≥3 y |
| 2001–2002 | GC/MS | Plasma | NCEH | ≥3 y |
| 2003–2004 | GC/MS | Plasma | NCEH | ≥3 y |
| 2005–2006 | — | — | — | — |
| 2007–2008 | — | — | — | — |
| 2009–2010 | — | — | — | — |
1
GC/MS, gas chromatography/mass spectrometry; Tufts University, Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging, Boston, MA; NCEH, National Center for Environmental Health, Centers for Disease Control and Prevention.