The main observed differences in serum spectra between CD patients and controls were lower levels of several amino acids (asparagine, isoleucine, methionine, proline, and valine), methylamine, pyruvate, creatinine, choline, methylglutarate, lactate, lipids, and glycoproteins and higher levels of glucose and 3-hydroxybutyric acid
. Notably, the best discrimination is obtained from CPMG spectra (Carr-Purcell-Meiboom-Gill spin echo sequence) , that is, from spectra in which signals arising from large macromolecules such as lipidic components are suppressed .
Pyruvic acid overlaps with phthalic, N-acetylaspartic, and glycolic acids; pyroglutamic acid overlaps with 3-hydroxybutyric acid
; phenylpyruvic acid overlaps with orotic and hydroxyisovaleric acids; and p-hydroxyphenyl pyruvic and phenyllactic acids overlap with xanthurenic and homogentisic acids.