Apolipoproteins C-II and C-III as nutritional markers unaffected by inflammation

Rapid turnover proteins (RTPs), such as transthyretin (TTR), retinol binding protein (RBP), and transferrin (Tf), provide an accurate assessment of nutritional status but are susceptible to inflammation. Lipid-related markers, which have short half-lives in serum, may be better suited for nutritional assessment. We sought to identify sensitive nutritional markers unaffected by inflammation.

Fasting serum samples were collected from 30 malnourished inpatients and 25 healthy volunteers. Malnourished inpatients were divided into 2 groups: a low-C-reactive protein (CRP) group (CRP < 20 mg/l, n = 15) and a high-CRP group (CRP ≥ 20 mg/l, n = 15). Lipid-related markers, traditional nutritional markers, RTPs, micronutrients, and ketone bodies were measured and compared among the groups.

Apolipoprotein (Apo)C-II and ApoC-III concentrations were lower in malnourished inpatients than in the control group. There was no significant difference in ApoC-II and ApoC-III between the low- and high-CRP groups. Carnitine transporters and ketone bodies did not show a significant difference among the three groups. Albumin, TTR, RBP, and Tf concentrations were lowest in the high-CRP group, intermediate in the low-CRP group, and highest in the control group.

These results indicate that ApoC-II and ApoC-III are appropriate nutritional biomarkers unaffected by inflammation.